1. ## Bunching Romex

I remember that in one of my electrical training classes, the instructor told us that not more than four strands of romex should be bunched through any feed through because romex still needs to dissipate heat. I was in a 6 year old house today and in the basement utility room (very near the sub-panel) there were several instances of 6 or 7 strands passing together through one opening in the floor joists. Is this just bad practice or is it a defect that should be made a review item?

2. ## Re: Bunching Romex

The thing is, when you have that many bundled together you have to derate them, example would be if there were 7 to 9 20 amp romex conductors for a distance of 24" that didn't split off you would need to derate them from 20 amp down to 17.5 amps.

But around here it is not uncommon to see 7, 8 or even 9 bundled together. As is in your case and most cases, the closer you are to the service panel, the more cables in a bundle.

Back to your picture, was the contractor consistent with the cutting of his holes through the engineered joists. Rarely do I see it done properly.

3. ## Re: Bunching Romex

Originally Posted by David McGuire
The thing is, when you have that many bundled together you have to derate them, example would be if there were 7 to 9 20 amp romex conductors for a distance of 24" that didn't split off you would need to derate them from 20 amp down to 17.5 amps.
9 two-conductor cables means 18 current carrying conductors, and 10-20 current carrying conductors is derated to 50%.

12 NMB is derated from 30 amps and 14 NMB is derated from 20 amps, so, presuming no derating for ambient temperature (i.e., not in an attic for example), 12 NMB would have a 15 amp rating (not suitable for anything greater than a 15 amp breaker) and 14 NMB would have a 10 amp rating (not suitable for anything at all basically).

Now, if *any portion* of the any one of those circuits goes through an attic, than that entire circuit also needs to be derated for ambient temperature, and if we presume a typical 125 degree attic, the derate rating is further derated to 76%, which would make 12 NMB derated to 11.6 amps (not suitable for anything at all basically), and 14 NMB derated to 7.6 amps (making it a wasted used of copper not suitable for anything).

And, if the attic temperature is higher than 131 degree (and up to 140 degrees) the ambient derating factor is 0.71 instead of 0.76, and if the attic temperatures reach 141 degrees to 158 degrees, the derating factor is 0.58.

What really kills bundling and lack of maintaining space is having to derate for ambient *and* more than 3 conductors, derating for more than 3 conductors is bad enough.

4. ## Re: Bunching Romex

In order for cables to be considered bundled they have to be in contact with each other for a minimum of 24 inches. And, as soon as the cables don't touch, the 24 inch minimum starts over. So, as long as cables don't touch continuously for over 24 inches they aren't bundled.

People fuss about this continuously, but the language in the NEC is very clear. And, there is seldom a bundle of NM-B where the cables are in intimate contact for 24 inches unless strapped with wire ties.

Cables running horizontally through framing usually don't have bundling issues, at least technically, because if you look closely the cables don't maintain contact. And, if some is found that does touch it takes a fairly light pressure to move a cable enough to make a space between it and a cable that touches.

If you look closely and objectively at both pictures there may be a couple of cables that would be considered bundled. But, even then it could be the angle the picture was taken from.

Close proximity doesn't count - the cables HAVE TO TOUCH CONTINUOUSLY for the 24 inches.

NEC 310 (B) (3) Adjustment Factors.
(a) More Than Three Current-Carrying Conductors in a Raceway or Cable. Where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.) and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(3)(a).

The rules change immediately if the bundle of cables goes through an opening required to be fire stopped.

Last edited by Bill Kriegh; 11-04-2011 at 08:35 PM.

5. ## Re: Bunching Romex

Originally Posted by Bill Kriegh
In order for cables to be considered bundled they have to be in contact with each other for a minimum of 24 inches. And, as soon as the cables don't touch, the 24 inch minimum starts over. So, as long as cables don't touch continuously for over 24 inches they aren't bundled.
Incorrect, cables like those in the photo are considered bundled and/or lack of maintaining spacing (take your pick, both are requirements). I've talked with engineers at the cable manufacturers, UL, and a several others, there are two trains of thought on "maintaining spacing": 1) start out at a box and fitting and "maintain" that spacing spacing; 2) maintain at least 1/4" separation between cables, and "maintain" that spacing all the way. Otherwise derating applies.

People fuss about this continuously, but the language in the NEC is very clear. And, there is seldom a bundle of NM-B where the cables are in intimate contact for 24 inches unless strapped with wire ties.
The wording in the NEC is very clear, and it very clearly does 'not' say what you said it does, it very clearly simply says:
- (a) More Than Three Current-Carrying Conductors in a Raceway or Cable. Where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.) and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(2)(a). Each current-carrying conductor of a paralleled set of conductors shall be counted as a current-carrying conductor.

That clearly does not say 'not touching'.

Cables running horizontally through framing usually don't have bundling issues, at least technically, because if you look closely the cables don't maintain contact. And, if some is found that does touch it takes a fairly light pressure to move a cable enough to make a space between it and a cable that touches.
The IAEI and its articles disagree with you. A few years ago they ran tests on just that and had a large article stating that, even though that does not violate the wording of the code, that practice does lead to building up a lot of heat at those areas and fires may have been started by that practice.

Close proximity doesn't count - the cables HAVE TO TOUCH CONTINUOUSLY for the 24 inches.
Very clearly incorrect - read the code, do not add your own wording and thoughts to it ... *the code* *does not say what you are saying it says* ... very clearly so.

There are many electricians who down play bundling and derating, yet the NEC "clearly" continues to include it as it is "clearly" an important factor.

6. ## Re: Bunching Romex

Jerry, I can certainly see BKs interpretation as the cables are parallel but the closest contact is only where they pass through a non-firestopped framing member. In the pic posted that area is a 1/2" thick plywood web. Well less than the 24" mentioned in the code. Also the "maintain spacing" is not defined as a distinct measurement. The 1/4" you posted about is the first time I have seen an actual dimension, but it is not in the code.

You mentioned start out at a fitting an maintain that spacing. A typically NM connector has the cables in intimate contact, although a small distance where the clamping takes place.

7. ## Re: Bunching Romex

Originally Posted by Jim Port
Jerry, I can certainly see BKs interpretation as the cables are parallel but the closest contact is only where they pass through a non-firestopped framing member. In the pic posted that area is a 1/2" thick plywood web. Well less than the 24" mentioned in the code.
That is the place where the cables are wedged together, yes, but not the point where lack of maintaining spacing occurs.

Also the "maintain spacing" is not defined as a distinct measurement. The 1/4" you posted about is the first time I have seen an actual dimension, but it is not in the code.
And, as I pointed out previously, Bill's "as soon as the cables don't touch" is not in the code either.

You mentioned start out at a fitting an maintain that spacing. A typically NM connector has the cables in intimate contact,
Not where one NM cable is in one NM cable clamp, which is what the spacing is based on for those whom I have talked with and who brought that up - there is a definite space between the NM cables where they enter the plastic box with the built-in clamps, there is also a definite space between the knock-outs/threaded hubs in metal/plastic boxes too, and that is 'the spacing' which the code could be referring to which needs to be maintained.

The code is not "clear" on "maintaining spacing", and Bill said it was "clear" in his post, that is why I referenced the code as 'not' being "clear" as it "clearly" is not "clear".

There are several types of NM cable standoffs which address and solve this problem.

When I have a question like this (regarding what is "maintaining spacing") I go to the sources to find out what they say, and the engineers for Southwire (you know, the manufacturers of RomexTM), and to UL, and to NFPA, and find out what they say.

That was probably about 10-15 or so years ago, and the engineers at Southwire said "No one has ever asked that question before" and they called a few of their other engineer's and at first said "I suppose that 1/4" would be maintaining spacing as the cables do need to ventilate and be able to dissipate the heat which may build up", and then one of the engineers said that could be read "as meaning the spacing between the connectors in the boxes is the spacing which needs to be maintained".

There are many electrician who simply feel that maintaining spacing is 'no big deal', but the NEC must consider it as still being a big enough deal as they keep that section in the code. When, or should I say "if" because I doubt it will happen ... when the NEC drops the requirement for maintaining spacing or drops the requirement to derate for not maintaining spacing, then I will follow them and quit "going there".

In the meantime, though, it still is a code requirement to derate if spacing is not maintained - that cannot be argued. The separation distance required is the only thing which can be argued - and it does get argued about now and then.

Added with edit: I forgot to add that the engineers at Southwire 'passed through' this when discussing what "maintaining spacing" was: one of them suggested that the width of a finger would suffice, then the discussion went to who's finger as fingers are different widths, another engineer solved that by saying that if the NM cables were spaced apart from other cables by the width of that cable, thus the larger the cable the more current and heat and the greater the spacing - all seemed to agree that was reasonable ... but unrealistic to expect ... thus they ended up at the 'spacing of the connectors to the boxes' and at ' 1/4" ' (which are definitely not the same, but that 1/4" was the closest spacing discussed.

Last edited by Jerry Peck; 11-05-2011 at 01:34 PM.

8. ## Re: Bunching Romex

Originally Posted by Jerry Peck
That is the place where the cables are wedged together, yes, but not the point where lack of maintaining spacing occurs.

Jerry, you gotta quit putting stuff in the book that isn't there

And, as I pointed out previously, Bill's "as soon as the cables don't touch" is not in the code either. Yes it is. In contact continuously for more than 24 inches means just that. If the cables are in contact for 23 7/8 inches, then move apart, then touch again for 23 7/8 inches, according to the wording in the NEC they aren't bundled. Doesn't matter what the intent is - the wording says what is or isn't OK and it says not bundled unless touching for more than 24 continuous inches.

Not where one NM cable is in one NM cable clamp, which is what the spacing is based on for those whom I have talked with and who brought that up - there is a definite space between the NM cables where they enter the plastic box with the built-in clamps, there is also a definite space between the knock-outs/threaded hubs in metal/plastic boxes too, and that is 'the spacing' which the code could be referring to which needs to be maintained. Could be, but doesn't. All the NEC says is "some" space must be maintained, and there's no rule it must be consistent, or what the minimum is.

The code is not "clear" on "maintaining spacing", and Bill said it was "clear" in his post, that is why I referenced the code as 'not' being "clear" as it "clearly" is not "clear". Very clear, they can't touch for more than 24 continuous inches. Spacing can be "piece of paper" wide or several feet. It is NOT defined

There are several types of NM cable standoffs which address and solve this problem. Most "stacker staples do not maintain anywhere near the distance between cables that holes in boxes have, and, incidentally, these holes and/or fittings can have 2 cables. A group of cables run vertically in a wall in one of these approved "stackers" winds up looking much like the runs of cable in the OPs pictures because the cables aren't perfectly straight. The spacing between the different "layers" in these stackers looks to be about 3/32 or so, hardly a 1/4" or a "finger", and at 2 cables per layer(4 of them) with no divider can touch in the stacker. Neither spacing is anywhere close to the spacing of the holes in a nail on plastic box or the holes in a 4 square metal box. Remember, these things are UL approved for the purpose.

When I have a question like this (regarding what is "maintaining spacing") I go to the sources to find out what they say, and the engineers for Southwire (you know, the manufacturers of RomexTM), and to UL, and to NFPA, and find out what they say. I know what the engineers say. What we're talking about here is what's in writing and has the force of law when applying the NEC to an installation

That was probably about 10-15 or so years ago, and the engineers at Southwire said "No one has ever asked that question before" and they called a few of their other engineer's and at first said "I suppose that 1/4" would be maintaining spacing as the cables do need to ventilate and be able to dissipate the heat which may build up", and then one of the engineers said that could be read "as meaning the spacing between the connectors in the boxes is the spacing which needs to be maintained".

There are many electrician who simply feel that maintaining spacing is 'no big deal', but the NEC must consider it as still being a big enough deal as they keep that section in the code. When, or should I say "if" because I doubt it will happen ... when the NEC drops the requirement for maintaining spacing or drops the requirement to derate for not maintaining spacing, then I will follow them and quit "going there".

In the meantime, though, it still is a code requirement to derate if spacing is not maintained - that cannot be argued. The separation distance required is the only thing which can be argued - and it does get argued about now and then.

Added with edit: I forgot to add that the engineers at Southwire 'passed through' this when discussing what "maintaining spacing" was: one of them suggested that the width of a finger would suffice, then the discussion went to who's finger as fingers are different widths, another engineer solved that by saying that if the NM cables were spaced apart from other cables by the width of that cable, thus the larger the cable the more current and heat and the greater the spacing - all seemed to agree that was reasonable ... but unrealistic to expect ... thus they ended up at the 'spacing of the connectors to the boxes' and at ' 1/4" ' (which are definitely not the same, but that 1/4" was the closest spacing discussed.
So, no need to go there. Put it in the NEC, put a label on the wire. Basically, do something about it besides say "this is what we think" and make it a rule.

What we have here is a Watsonism - some CMP or some engineer said something to somebody somewhere so I know what the intent is and you don't so a I'll tell you. Sorry Doesn't matter. It's not in the NEC what the spacing needs to be, and it isn't on cable packaging or instructions either.

Yes, a properly installed installation dictates there needs to be spacing between cables. But, with the language in the book, you'd loose in court if you said either of the OPs pics showed bundling based on the written material available. Maybe someday we'll chat about how I know that for a fact.

9. ## Re: Bunching Romex

Bill ... *I* need to stop putting words in the book??;

*You* need to quit putting words in the book.

*No where* im the book does it say the cables only need to not touch.

Your post sounded like Watson trying to defend some of his posts.

10. ## Re: Bunching Romex

Originally Posted by Bill Kriegh
Yes, a properly installed installation dictates there needs to be spacing between cables. But, with the language in the book, you'd loose in court if you said either of the OPs pics showed bundling based on the written material available. Maybe someday we'll chat about how I know that for a fact.
I replied using my smart phone for my previous post - those small screens are just not made for this stuff, anyway, after re-reading your post on my computer ...

"you'd loose in court if you said either of the OPs pics showed bundling based on the written material available."

The other party would not win either ... for the same reason. Which means if they sued me, they would not win.

And there is no reason for me to sue them, if they want to overcome my statement they would be suing me.

11. ## Re: Bunching Romex

Asking a few people sitting around a table about their thoughts about spacing hardly seems like an official way to determine the defintion of maintaining spacing. Especially when variables like KO spacing or about a finger width are mentioned. I doubt the any NRTL would use such a variable condition in a valid test to determine negative effects due to heating etc. As I stated above many UL listed NM connectors can accept two cables and this places the cables in intimate contact. This contrasts with some of the roundtable "data" that was posted above. Suppose that a 4 square box is used but only the two outside KOs are used on one side. Does this now mean that the cables need to remain 2" apart for their entire distance? If they do not you have not maintained the spacing. Would adding a cable to the middle KO violate the spacing? Single gang plastic boxes can have two flat cables enter through the same KO tab. What is the spacing now? Certainly less than 1/4", more like 1/16".

12. ## Re: Bunching Romex

Originally Posted by Jim Port
As I stated above many UL listed NM connectors can accept two cables and this places the cables in intimate contact.
And, even by your posts and Bill's posts, if that "intimate contact" was maintained for more than 24" derating would be required.

So, as I posted above, there can be *no* argument that derating is a *code requirement* when bundled or lack of maintaining spacing. The *only thing* which can be argued is *what exactly is that spacing*.

I also added that has been argued here before, and, apparently, still is being argued here ... as neither you nor Bill have anything which proves your side of the argument any more than I do which proves my side of the argument ... so ... let's keep arguing ... only let's argue about what the code *does say* - *that derating **is** required* for certain conditions ...

Are you and Bill saying that derating *is not* required for certain conditions? (If you are, then I win that one hands down and in black and white code wording. )

13. ## Re: Bunching Romex

I would not say that derating is not necessary, but that the "maintained spacing" is entirely ambiguous. I don't necessarily believe that parallel cabling automatically means that they are bundled. I also read the code that it is only an issue if the 24" is in continous contact. I forget who posted about the 23 7/8" of contact with a gap and 23 7/8 would be compliant but the wording can certainly be seen to support that viewpoint. This is reinforced by the similar restriction about derating in nipples only applying if the nipple is greater than 24".

14. ## Re: Bunching Romex

Originally Posted by Jim Port
I also read the code that it is only an issue if the 24" is in continuous contact.
The code does not reference in continuous contact in any way. The code only references "without maintaining spacing for a continuous length" but does not define what "maintaining spacing" is.

Take your typical "bundle" where the cables are "bundled" with tie-wraps even spaced at every 6" to 12" - I am sure that you would call that a "bundle", I suspect that anyone would call that a "bundle". Yet the cables may very well not be "in continuous contact" all the way along that "bundle". But surely the cables are not "maintaining spacing for a continuous length" for that 24".

If you look at (b) in the adjustment factors you will get a sense on where the spacing to be maintained may be from the NM cable clamps in the boxes/enclosures they enter/exit:
- (b) More Than One Conduit, Tube, or Raceway. Spacing between conduits, tubing, or raceways shall be maintained.

"Where" do the above conduit/tubes/raceways enter boxes/enclosures? That "spacing between" the conduits/tubes/raceways "shall be maintained".

If that "spacing" is the "spacing" which "shall be maintained", why would that be any different than the "spacing" between where the NM connectors where those NM connectors enter the boxes/enclosures.

*That* could very well tip the favor of interpretation in my favor and make my case "winnable", or at least make the opposing party's case "not winnable" such that I would win by default as the suing party would need to prove their case, and (b) certainly would override any "as long as the cables are not continuously touching" argument because the code acknowledges that "spacing" as being applicable to 'other wiring systems' and that "spacing" "shall be maintained", ergo, the spacing between the connectors for NM cable may well be considered the "spacing" which "shall be maintained" for NM cable as well.

Food for thought. I will await seeing you in court to decide this.

15. ## Re: Bunching Romex

I defy you to find any fastening system for NM-B, short of gluing them together with a continuous spacer, that maintains the same spacing between the cables, or any UL listed fastener that maintains the spacing of "box holes' and keeps the spacing "the same between cables" when used with multiple cables. If what you are pushing was actually what is required then you couldn't run more than one cable through a drilled hole (unless bigger than rules for drilling in framing allow). Even the article for requiring derating on a fire stopped hole references 2 cables in a hole

I've been doing this a long time and am well aware of the hows and whys of derating, and apply them when the situation requires it. I do, however, regularly take people to task who can't justify an inspection failure with a reference from the NEC that describes the situation. You haven't done that here. Even if I agreed with your reasoning for derating, which, incidentally, for the most part I do, I don't see a thing here requiring it applied like you want it to.

Come on Jerry, is there a part of "continuous length longer than 24 inches" that isn't clear? Is there something unclear about things having a "space maintained between them" that gets us to insinuating that the space has to be the same exact (width or length of) space? According to the dictionary if you maintain a space, you maintain an area where things don't touch. I'm not finding anything that says that that space has to be unchanging.

Again, knowing something to be what's intended because aunt Betty knows a guy whose brother is the employee of a boss whose partner plays golf with an engineer whose group leader sits on a code panel just doesn't cut it. Put it in writing and the problem goes away, sort of like your stand on marking tape and paint for some applications.

16. ## Re: Bunching Romex

Jerry, I will say that no inspector I have met interprets the article the same as you and enforces it more like Bill sees it. If your interpretation was enforced even running cables parallel along a stud from a switch would be in violation as the spacing might waver from the distance between KOs. I see your side similar to your take on 312.8 and how it is seen by the trades and inspectors. BTW 312.8 now has that wording revised and does not say " for that purpose".

As in the original pic I can't see that being called bundled in the trade. Now the cables to the right side of that picture I would consider bundled.

17. ## Re: Bunching Romex

Originally Posted by Jim Port
Jerry, I will say that no inspector I have met interprets the article the same as you and enforces it more like Bill sees it. If your interpretation was enforced even running cables parallel along a stud from a switch would be in violation as the spacing might waver from the distance between KOs. I see your side similar to your take on 312.8 and how it is seen by the trades and inspectors. BTW 312.8 now has that wording revised and does not say " for that purpose".

As in the original pic I can't see that being called bundled in the trade. Now the cables to the right side of that picture I would consider bundled.
Just for clarification, there are two pictures here. In the first picture, toward the back, you can see lines that are zip tied together. I would consider those bundled as well. In the second picture, to the right, I would agree with Jim that those are bundled. Anyone discuss zip tying bundled lines?

18. ## Re: Bunching Romex

Originally Posted by Harry Turner
Just for clarification, there are two pictures here. In the first picture, toward the back, you can see lines that are zip tied together. I would consider those bundled as well. In the second picture, to the right, I would agree with Jim that those are bundled. Anyone discuss zip tying bundled lines?
The (mostly) white items with the "wire"-ties look like PEX tubing and not like NM. In the first photo, there is a blue one breaking out of the bundle.

Last edited by Ronald Kornmiller; 11-07-2011 at 08:56 AM. Reason: wrong photo referenced

19. ## Re: Bunching Romex

I saw the white wires as CATV or other low voltage. As for the bunching of the NM cable, it wouldn't be mentioned in my report, as I would not consider that to bundled or in contact for more than 24 inches.

20. ## Re: Bunching Romex

*Poof*

Last edited by Lou Romano; 11-11-2011 at 01:50 PM. Reason: Because it was pointless to debate it here!

21. ## Re: Bunching Romex

Originally Posted by Lou Romano
Derating of cables in a house that are never ever ever and I stress, never ever ALL loaded up continuously ... give me a break! There should be many more exceptions to the rules!
Ah ... but *there are no exceptions* to those rules.

The NEC has *not* decided that wiring in dwelling units does not need to be derated!

22. ## Re: Bunching Romex

Those cables running parallel are definately "bundled". Those perpinducular not. Howeber the butcherhing of the PRIs are concernng. Tearouts, etc. worthy of further exploration. Exposed wiring and sharing tearouts/knockouts with SED and communications cabling concerning. BTW, those webs are OSB not ply. More concerned about voids in bottom of photos and where in span/structural integrity and protection from damage perp. multiple rip-outs not knockouts or spec'd bored holes, than "bundling" issues; and tha suspected non-support (except by the strained cabling) of the drain. What else his spwas sharing/occupying space of this "utility" area, laundry facitilites ?

Last edited by H.G. Watson, Sr.; 11-07-2011 at 10:44 PM.

23. ## Re: Bunching Romex

I've know I'm not the only one that feels like I do about bundling and the 24 continuous inches. Check out the following product link, UL approvals and all, and then check out the fill chart.

http://www.aifittings.com/products/s...s/cableway.pdf

24. ## Re: Bunching Romex

As an inspector, I would not consider the cables bundled together unless the installer employed the use of some mechanical means to ensure that such cables did indeed come onto contact with one another for 24 inches continuously. (ty wraps, etc.)

NM cables, properly sized for the branch circuit being fed, will not overheat under normal operating conditions. Consider the fact that even cables pulled through a raceway most likely are not in direct contact with one another for 24 inches continuously, however, I would use the derating table for such an installation as it seems conclusive that the intent of the code was meant for those installations, even though without Xray vision, I cannot verify that conductors abut, touch or do not maintain spacing. This is just common sense.

Since installations such as those depicted are customarily performed as long for as long as I've been an electrician, it would seem that ff the code was intended to compel derating of NM cables run adjacent to one another continuously, then it is my belief that wording to that extent would be specified in the code. (Or even the code handbook.)

The fact that #14 and #20 guage NM cable is already derated per code in residential installations makes it illogical to assume that further derating is necessary.

The code can be difficult to interpret as evidenced here in this forum. Differing opinions will always come into play and most inspectors do not perform inspections with the concern for how such would hold up in court.

Inspections should be performed with an understanding of the code and common sense. Speculation of the meaning or intent which is not demonstrably worded should not influence an inspection. Let the lawyers sort that out.

I am not intending the above as being directed towards anyone specifically in a nefarious or pejorative manner. It is obvious that some members of this forum seemingly demonstrate legal expertise or purport to have knowledge of such. Inspectors should use common sense. Do not read anything into the code that just isn't there. If I performed inspections in the manner that some of the posts in this forum contend to be enforceable, nothing would ever pass inspection and I would be in constant conflict with electrical contractors.

As I've indicated on numerous occasion to my supervisory personnel, "You didn't hire an attorney, you hired a licensed master electrician with 25+ years of experience in the electrical contracting field. If you wanted an attorney.....you should have hired one."

25. ## Re: Bunching Romex

............

Last edited by ken horak; 03-30-2012 at 08:34 PM.

26. ## Re: Bunching Romex

Originally Posted by Bill Kriegh
I've know I'm not the only one that feels like I do about bundling and the 24 continuous inches. Check out the following product link, UL approvals and all, and then check out the fill chart.

http://www.aifittings.com/products/s...s/cableway.pdf
Unless I missed it ... ... that does *not* say *derating does not apply*.

The NEC does not say you are not allowed to lay as many NM cables as you want side-by-side-by-side-by-side-by-... the NEC DOES say that *if you do that, then you shall derate the ampacity in accordance with that table. By the way, go to that table and you will see that you can put 10,000 NM cables side-by-side-by-side-by-side-by-... but if you do have more than 41 current carrying conductors (you would have 20,000 current carrying conductors) then you shall derate the ampacity to 35% of the listed ampacity.

So, go ahead and fill those suckers up ... just make sure you derate the conductors.

Bill, these supports solve the derating problem by separating the cables: CS4 Cable Standoff - Arlington Industries Resource Center

27. ## Re: Bunching Romex

Jerry im loving it you are right

The ignorance of someone saying you can open a little space every 23 inches and continue bundling for another 23 inches is unreal thanks for wording it well

28. ## Re: Bunching Romex

Well, I haven't read all the arguments about code and stuff in this thread, but I have a feeling this photo shows improper bundling...correct? These are connected to two 200 Amp C/B panels. I'm not familiar with this type of installation, where the NM is in PVC conduit. Is this the "raceway" some of you were talking about earlier, or is it called something else?

(I am not allowed to open the panel cover to investigate more throughly.)

Last edited by Kristi Silber; 11-12-2011 at 06:43 PM. Reason: add photo

29. ## Re: Bunching Romex

Originally Posted by Mark S. Connely
Jerry im loving it you are right

The ignorance of someone saying you can open a little space every 23 inches and continue bundling for another 23 inches is unreal thanks for wording it well
You may think it is unreal or ignorance but that is what the wording says. This is no different than wiring in a nipple that is 24" or less not needing to be derated. Install a nipple 24 1/8" long and you would need to derate.

Sorry Mark.

30. ## Re: Bunching Romex

Nevermind. I have read some of the posts here and in a related thread, and it must be wrong to wire like this. Just surprises me, because it's a well-designed and -built house otherwise.

31. ## Re: Bunching Romex

Originally Posted by Jim Port
You may think it is unreal or ignorance but that is what the wording says. This is no different than wiring in a nipple that is 24" or less not needing to be derated. Install a nipple 24 1/8" long and you would need to derate.

Sorry Mark.
Careful Jim. I'm being put in my place - again

32. ## Re: Bunching Romex

Originally Posted by Jim Port
You may think it is unreal or ignorance but that is what the wording says.
Jim,

You keep saying that is what the wording says, but the wording does not say that. You are making words up.

This is no different than wiring in a nipple that is 24" or less not needing to be derated. Install a nipple 24 1/8" long and you would need to derate.
Jim, nipples and raceways longer than 24" are addressed separately from the "lack of maintaining spacing", nipples are just short raceways and the restrict the conductors ability to dissipate heat and stall cool, there is no "lack of maintaining spacing" requirement for conductors in raceways.

33. ## Re: Bunching Romex

Originally Posted by Kristi Silber
I have a feeling this photo shows improper bundling...correct?
Kristi,

There are other problems with that installation as well, but first a question: How long were those raceways, i.e., how far from the top of the panel to the ceiling?

34. ## Re: Bunching Romex

I was using the nipple as another example to counter Marks view about a slight difference in length making a difference between needing to derate or not.

I am taking the stance that if the spacing is not maintained they would be in contact. Not that the spacing must a a defined or constant amount. If they are not continuous for 24" or more than that section does not apply. This is that way that every electrical inspector in my experience has seen this issue.

35. ## Re: Bunching Romex

Originally Posted by Jim Port
I was using the nipple as another example to counter Marks view about a slight difference in length making a difference between needing to derate or not.
Jim,

I fully understand that point, but they have to draw the line in the sand someplace ... is it 6" - 12" - 24" - 5' - 10'?

I am sure that there were some calculations used at some point which showed that 12" was 'no big deal' but that 48" was a 'big deal', so for safety they backed it down to 24" instead of some intermediate number to give a 'greater safety factor' in the number.

36. ## Re: Bunching Romex

I guess I could have also used the 3 hour rule concerning continuous loads. Two hours 59 minutes = non-continuous. Leave it on another minute and it is now continuous and would need to drop to 80% of the breaker rating.

37. ## Re: Bunching Romex

Originally Posted by Jim Port
I guess I could have also used the 3 hour rule concerning continuous loads. Two hours 59 minutes = non-continuous. Leave it on another minute and it is now continuous and would need to drop to 80% of the breaker rating.
Like speed limit signs where 60 mph is okay but 61 mph is not.

38. ## Re: Bunching Romex

Originally Posted by Jerry Peck
Like speed limit signs where 60 mph is okay but 61 mph is not.
Did someone tell you that speed limits were that low? I have heard the Jag likes to cruise a little faster than that.

39. ## Re: Bunching Romex

Originally Posted by Jerry Peck
Kristi,

There are other problems with that installation as well, but first a question: How long were those raceways, i.e., how far from the top of the panel to the ceiling?
I believe they were about 3 1/2 ft. This house has 10 ft. ceilings.

I suspect the homeowner "installed" the ceiling drywall. Wish I could see above it.

Here are the panels the raceways were above, FWIW, both 200 Amp.

40. ## Re: Bunching Romex

Originally Posted by Kristi Silber
I believe they were about 3 1/2 ft. This house has 10 ft. ceilings.

I suspect the homeowner "installed" the ceiling drywall. Wish I could see above it.

Here are the panels the raceways were above, FWIW, both 200 Amp.
The installation that you have pictured is typical here in upstate NY.
The cables are installed in PVC for the purpose of protecting such from "physical damage" where exposed to such.
"Physical Damage" is what is usually the determining factor of "uses permitted" as it pertains to NM cable.

No one has commented on the fact that I raised in a previous post regarding the fact that NM cable is already derated for residential wiring in the first place.

I have NEVER observed NM cable installed in a manner consistent with this thread to be subject to overheating or derating for that matter.

Again, the opinions of some posters here would result in very few installations being approved and I feel that the opinions reflected here are often extremely stringent and interpret code in a manner that is inconsistent with reality.

Once again, I am not an attorney, I am an electrical inspector.

If they wanted attorneys inspecting such, then hire them.

For an inspector to perform in the capacity required, they should have a plethora of field experience so that they may apply code in a realistic manner.

Leave the strict interpretations for litigation testifying.

Show me ONE example of NM cable overheating in such an installation....just one.

If properly sized for the branch circuit being fed....THERE WILL BE NO PROBLEM and there is no rational reason to derate such.

41. ## Re: Bunching Romex

Incidentally an electrician called me about his helpers putting romex in conduit like in Kristi's pics. He wanted to know if I objected, and I listened to his reasoning about neatness, short length of the conduit, and the fact that many residential circuits go unused most of the time.

I agree with Richard, that hardline by the bookism may be appropriate for litigation it falls short of day to day practicality.

I am the AHJ for two small local bodies here, as my home inspecting is slow as molasses in winter these days.

42. ## Re: Bunching Romex

I appreciate the comments about the photo I posted. This discussion makes me wonder how different types of conduit/armor disperse extra heat. I would think PVC would be less able to conduct heat away from cables within.

I'm interested in the other things Jerry mentioned he saw wrong with the installation. Cables going directly through drywall?

43. ## Re: Bunching Romex

Originally Posted by Kristi Silber
I'm interested in the other things Jerry mentioned he saw wrong with the installation. Cables going directly through drywall?
Kristi,

Are those panels in a garage? If so, the openings in the ceiling around the conduits are a concern for lack of separation as required.

The NM cables coming out of conduit marked '4' is nice and tightly tied together, and, despite what some say above, the NEC *REQUIRES* derating in residential installation ... whether those individuals like it or not, or whether those individuals agree or not. The same applies to the NM cables coming out of the conduit marked '6'.

The conduits marked '1' and '2' extend up into the ceiling and are required to end below the ceiling. The same for the conduit marked '5', and possibly for the conduit marked '7'.

The tops of the conduits need to be terminated in a proper fitting which protects the NM cables from damage from sharp edges in the conduit, a bushing would work 'best'.

Additionally, the conduits are supposed to be sealed at the tops.

The NM cables are required to be properly supported and secured within 12" of the where they exit the conduits.

And, of course, as I stated at the beginning, at 3-1/2' long, the NM cables need to be derated, and if any of those NM cables go into the attic, the derating for ambient temperature needs to be taken as well.

Let's take the conduit marked '4' as an example:
- I see 5 2-conductor NM cables there, and the bundle looks like there are at least 2 more cables behind the ones which are visible. That means there are 7 2-conductor cables in that conduit, and that the number of current-carrying conductors is 14 (7 x 2 = 14).
- Let's presume those are older NM cables and that they may be 12 AWG conductors which have an ampacity for derating of 30 amps.
- The derating factor for 14 current-carrying conductors is 50, multiply the 30 amp ampacity for derating times 50 and you get a derated ampacity of 15 amps. And that is with *no* derating for high ambient in an attic.
- Those 12 AWG NM cables would require overcurrent protection *no greater than* 15 amps.
- Now let's presume that those NM cables also go into the attic, and that the attics in your area get to, say, about 135 degrees F in the summer. The derating for that ambient temperature is 0.71. We now multiply the 15 amp derated ampacity times 0.71 for a new derating of 10.65 amps, which means that those 12 AWG NM cables are only suitable for a 10 amp overcurrent device - try to find a 10 amp breaker!

There will be some responses which say the above is not applicable to residential, or that it is not needed, however, that is *THEIR OPINION* as 'feel-good' chatter, however, the NEC *REQUIRES* that derating be applied.

They also talk about 'that only applies when you go to court', well, THE REASON it went to court is because it was installed wrong, not derated properly, and now the whole mess ends up in court and THEN ... that is when they say 'Oh, yeah, NOW we will apply the derating factors'. But if they had been paying attention and applied the derating factors FIRST they would not be 'in court'. Sheesh, one wonders what they are thinking - they WANT to end up in court so they can apply the derating factors???

"First Preventers" ... remember that from another post I made recently?

44. ## Re: Bunching Romex

Jerry, thank you very much for the informative post. Electrical systems are definitely my weakest spot, and I've learned so much from this forum.

This is a house built in 2000. The panels aren't in the garage, and there is no attic. (Flat roof, very modern, has a huge curved sound shield perched on the front. \$1.1 mil in today's market. A fun one to survey.) These aren't people who want to be limited in their amperage, so it's pretty safe to say the cables are not derated.

I was just reading that the most common thing to ignite first in a distribution and lighting res. electrical fire is the wire insulation.

Let's presume those are older NM cables and that they may be 12 AWG conductors which have an ampacity for derating of 30 amps
For all know, it could be 10 AWG. Ten foot ceilings, too high to see.

45. ## Re: Bunching Romex

Just some random thoughts regarding a recent post.

Conduits require ends......chases do not.

Since we seem to have "Litigation Consultants" pontificating on electrical inspection practices employed in the real world and not a courtroom, if not derating such installations results in litigation, provide one example of NM cables being bundled in such a manner causing a fire or even overheating that resulted in such a litigious circumstance.

Just one. that's all I ask.

If all inspectors scrituinized installations in the manner professed in this forum on a continual basis by consultants:

A) Nothing would ever pass their unrealistic expectations
B) The plethora of complaints lodged against such an inspector would result in their untimely removal from such a position.

I'm not trying to personally retaliate against anyone but some of the opinions as expressed in this forum are absolutely ludicrous.

And providing such unrealistic opinions to self-professed new HI's is deleterious to that profession as well.

I would speculate that NM cable bundling will be encountered in a majority of home inspections.

I've engaged in the practice of wiring residential properties in this customarily accepted manner and have stamped inspections utilizing such without compunction.

To write such up and possibly cause a homeowner to expend funds to ameliorate such an ordinary and accepted practice will complicate numerous real estate transactions un-necessarily.

I've been installing and inspecting for 30+ years and have never been subject to nor participated in such rigid interpretations of the electrical code.

If my opinion as reiterated is incorrect, then let other experienced electrical inspectors and licensed master electricians admonish me and I will reconsider my estimation of such a practice.

I have never seen nor heard of any problems resulting from such a practice provided that the branch circuits are installed properly in the first place.

To those whom interpret this Marine Corps veteran as being ascerbic in my commentary, I can assure you there is no disrespect intended.

It's just that enough is enough!

46. ## Re: Bunching Romex

Richard

Right On! Thank you.

47. ## Re: Bunching Romex

"And providing such unrealistic opinions to self-professed new HI's is deleterious to that profession as well."
I think you mean me. Actually, I'm not a HI at all, I do surveys for insurance companies. We aren't trained to go into this kind of detail, but I like to know about potential safety issues anyway.

I'm obviously not knowledgeable about this stuff to take a stance, but "better safe than sorry" seems to me a reasonable view when it comes to code and fire safety.

Here's a report of an experiment measuring temperatures of bundled NM. The authors suggest the code isn't conservative enough is its requirements for bundled NM. Just one, unrepeated experiment, but worth considering.
http://www.copper.org/applications/e...ion_report.pdf

This site suggests that bundling is one of the top reasons electrical inspections fail in a MD county - so evidently some inspectors, anyway, do write it up.
http://frederickcountymd.gov/documen...il%20final.PDF

48. ## Re: Bunching Romex

Originally Posted by Richard D. Fornataro
Conduits require ends......chases do not.
They do where the cables and conductors exist so as to not damage the cables and conductors.

If all inspectors scrituinized installations in the manner professed in this forum on a continual basis by consultants:

A) Nothing would ever pass their unrealistic expectations
B) The plethora of complaints lodged against such an inspector would result in their untimely removal from such a position.
Inspections DO pass because the contractors learn that the code they say they are building to is the same code they are being held to.

Do you tell your customers and AHJ that you don't care what the code says, that you are going to do it *YOUR WAY*? I'm guessing that your contracts state that you will do the work in accordance with the codes ... and here you are complaining about being held to the same codes you contracted to be held to.

Sounds a bit two-faced to me, not that I am trying to retaliate against anyone for them being absolutely ludicrous and two-faced ...

And providing such unrealistic opinions to self-professed new HI's is deleterious to that profession as well.
Expecting contractors to be held to the code the contractors say they are performing to is deleterious to the profession? You have it backward - CONTRACTORS not wanting to perform to the code THEY SAY they will perform to is deleterious to their trade.

I would speculate that NM cable bundling will be encountered in a majority of home inspections.
And in the majority of AHJ inspection too, but that does not make it right, and the contractors obligation is to do what they said they would do - - - NOT ONE CONTRACTOR has come into the building department and said "I am going to do this job the way *I* want to, to heck with the codes.", that is because they know they would not be issued a permit if they said that.

I've engaged in the practice of wiring residential properties in this customarily accepted manner and have stamped inspections utilizing such without compunction.
Is that your way of saying to you do not wiring to the codes, and you know that, and you just do not care?

It's just that enough is enough!
Correct: Enough is enough, and it is enough of contractors saying to disregard the codes because *THEY* don't think they should do the work that way. Absolutely correct - enough of that crap work is enough!

49. ## Re: Bunching Romex

Originally Posted by Kristi Silber
Here's a report of an experiment measuring temperatures of bundled NM. The authors suggest the code isn't conservative enough is its requirements for bundled NM. Just one, unrepeated experiment, but worth considering.
http://www.copper.org/applications/e...ion_report.pdf

This site suggests that bundling is one of the top reasons electrical inspections fail in a MD county - so evidently some inspectors, anyway, do write it up.
http://frederickcountymd.gov/documen...il%20final.PDF
Kristi,

More inspectors write up bundling than most electricians think ... until the inspectors in their area get a clue and start writing the local electricians up, then they scream and cry like a baby that the inspectors are picking on them.

The contractor submits the plans and drawings to the building department for approval, and those plans and drawing need to meet code minimums. Then the contractor tries to build it differently and complains that the inspector is picking on them for not doing what they said they would do. Sheesh! Who would of thunk that the contractor would actually do what they said they would do?

50. ## Re: Bunching Romex

Now, now, no fair generalizing, I'm sure there are lots of contractors out there who follow code conscientiously. But it's too bad that there are so many exceptions. I won't say more than that - this is one debate I'll stay out of.

51. ## Re: Bunching Romex

Originally Posted by Jerry Peck
They do where the cables and conductors exist so as to not damage the cables and conductors.

Inspections DO pass because the contractors learn that the code they say they are building to is the same code they are being held to.

Do you tell your customers and AHJ that you don't care what the code says, that you are going to do it *YOUR WAY*? I'm guessing that your contracts state that you will do the work in accordance with the codes ... and here you are complaining about being held to the same codes you contracted to be held to.

Sounds a bit two-faced to me, not that I am trying to retaliate against anyone for them being absolutely ludicrous and two-faced ...

Expecting contractors to be held to the code the contractors say they are performing to is deleterious to the profession? You have it backward - CONTRACTORS not wanting to perform to the code THEY SAY they will perform to is deleterious to their trade.

And in the majority of AHJ inspection too, but that does not make it right, and the contractors obligation is to do what they said they would do - - - NOT ONE CONTRACTOR has come into the building department and said "I am going to do this job the way *I* want to, to heck with the codes.", that is because they know they would not be issued a permit if they said that.

Is that your way of saying to you do not wiring to the codes, and you know that, and you just do not care?

Correct: Enough is enough, and it is enough of contractors saying to disregard the codes because *THEY* don't think they should do the work that way. Absolutely correct - enough of that crap work is enough!

Sometimes it is better to remain silent and be thought of as ignorant than to speak and remove all doubt.

You're opinions are inconsistent with reality.

I am seriously doubting you have endeavored in the field other than in a courtroom.

Your commentary continues to reflect that your livelihood is derived from twisting the truth and refusing to comprehend that which is written.

If you had field experience you would know that you don't close a chase.

You have failed to respond to the challenge of citing any incidence where such a practice results in catastrophic results.

You continue to pontificate ad nauseum concerning code but your commentary reflects the fact that you do not exist in the real world.

I will match the respect I receive from my peers against your erratic spewing of codes any day.

Make all the derogatory comments you like.

I think the patrons of this forum know you for what you are.

"When people show you who they are.......believe them."

In the future, I will choose not to argue with your delusional view of inspection practices simply because I don't have to.

The past reflects that to continue such is an exercise in futility.

The best way to handle a child throwing a tantrum is to ignore them.

Have a nice life.

Last edited by Richard D. Fornataro; 11-17-2011 at 06:22 AM. Reason: spelling and typo correction.

52. ## Re: Bunching Romex

Originally Posted by Richard D. Fornataro
I am seriously doubting you have endeavored in the field other than in a courtroom.
Then you most certainly have not been reading what I write.

No wonder there is a lack of communication debating with you ... you cannot carry on a debate unless you pay attention and follow what the other person says (writes).

Originally Posted by Richard D. Fornataro
The best way to handle a child throwing a tantrum is to ignore them.
Then I shall try to ignore you.

53. ## Re: Bunching Romex

Sometimes it is better to remain silent and be thought of as ignorant than to speak and remove all doubt.

You're opinions are inconsistent with reality.

I am seriously doubting you have endeavored in the field other than in a courtroom.

Your commentary continues to reflect that your livelihood is derived from twisting the truth and refusing to comprehend that which is written.
I should really stay out of this, but I just have to say I find these comments utterly ridiculous and totally unfounded.

And I find it frightening that an electrician will flaunt in public the fact that he doesn't follow code as a contractor OR inspector, especially since his comfort in doing so must mean that there are others doing the same thing.

54. ## Re: Bunching Romex

Kristi, anybody that says they will not comply to codes to officals or others is just waving a red flag at a bull. they are looking for a fight that they are not going to win in the long run. reason being is if you say that regularly and word get's around there will always be someone out there to take you down.

Yes codes do not get followed all the time, but when they get caught there is a price to pay for it. it's like speeding we all do it sometimes and sometimes we get caught. but not all the people will be caught, some that do are involed in accidents and death's. the same thing happens in non code compliance.

as for the fighting and disagreements they will always be there, sometimes you have to put on blinders on and focus on what is right or questionable and try and learn the differance

55. ## Re: Bunching Romex

Code is open for interpretation.

The Building Code in Ontario routinely has appeal hearings for those who wish to question the code.

Sometimes the code is upheld other times it is interpreted in another way and what the respondent is asking for is granted.

Appeals & Approvals

Appeals & Approvals

A fair and effective building regulatory environment provides mechanisms whereby decisions of enforcement officials can be appealed, and where innovative building materials may be approved and introduced to market. Accordingly, Ontario's Building Code Commission operates as an expert adjudicative body where Building Code disputes are heard in a timely manner. In addition, the Building Materials Evaluation Commission and Minister's Rulings serve as ways to receive evaluation and approval for new building products.

56. ## Re: Bunching Romex

Mr. Peck,

To all other posters to this forum,

Anyone who thinks that I was indicating that I choose to not follow codes is mistaken.

What I did indicate is that nobody I know would derate NM cable installed in the manner originally posted.

It's that simple.

Just because one person chooses to peck at every word, phrase and sentence written by everyone in this forum does not make their opinion weigh anymore heavily than anybody else's.

I'm counting on a majority seeing my point of view on this.

If not, I'll take the hint and stop posting.

Thank you.

Last edited by Richard D. Fornataro; 11-18-2011 at 07:04 AM. Reason: additional commentary

57. ## Re: Bunching Romex

Richard

Don't stop posting. I enjoy your retorts.

58. ## Re: Bunching Romex

Originally Posted by Richard D. Fornataro
Anyone who thinks that I was indicating that I choose to not follow codes is mistaken.
That's not the way you put it previously, but that's good to know.

What I did indicate is that nobody I know would derate NM cable installed in the manner originally posted.
You seem to live in a different world than many of us, take Kristi's link at bundling being one of the main write-ups there ... and that is not the only place. The world is an ever changing place and as codes are adopted in more places, codes are more closely followed in places where they have already been adopted, it's the natural progression of things: more people becoming familiar with codes leads to more knowledge of the codes, and more knowledge of the codes leads to greater enforcement of the codes as the overall intent of the codes of to protect the health, welfare and safety of the public, and ignoring what is adopted as "the minimum standard" leads to bad things happening.

Cheers!

59. ## Re: Bunching Romex

Originally Posted by Richard D. Fornataro
Just because one person chooses to peck at every word, phrase and sentence written by everyone in this forum does not make their opinion weigh anymore heavily than anybody else's.
Trying to defend a practice which has long been acknowledged as creating a potentially hazardous condition is ... well ... "indefensible".

As you obviously feel there is no harm in the practice being discussed, how about if you submit a code change and have them just remove that section? If they remove it, I will agree with you, but until then, I am in agreement with the code.

60. ## Re: Bunching Romex

Anyone who thinks that I was indicating that I choose to not follow codes is mistaken.

What I did indicate is that nobody I know would derate NM cable installed in the manner originally posted.

Richard, isn't this a contradiction? It looks to me like there are at least 6 cables bundled for at least 24 inches, in direct contact with each other. That's against code. (And please don't stop posting just because of a disagreement about this one thing! But also please don't make assumptions about others' experience. In Jerry's case you are most definitely wrong.)

Raymond, I'm sure some parts of code are open to interpretation; most lengthy documents are. But that doesn't necessarily mean that the code itself is flexible, it just means that parts may be read differently by different people. There may well be instances when circumstances are such that the reasons behind the code don't apply, and exceptions are appropriate (um, bundling through exterior conduit in the Arctic Circle?). The problem is when contractors (or inspectors) take it upon themselves to disregard code just because they feel it's generally unnecessary or overly stringent.

61. ## Re: Bunching Romex

Raymond, I'm sure some parts of code are open to interpretation; most lengthy documents are. But that doesn't necessarily mean that the code itself is flexible,
We'll have to disagree. In Canada the Chief Building Official has the power to review and accept alternative solutions to the code. There is also an appeal right where the building code can be enforced as written or the panel can allow a variance.

Electrical issues do not come under the purview of the building code officials that is separate and overseen by the Electrical Safety Authority (ESA). I can tell you from first hand experience exceptions to the electrical code do take place. I have seen a number of issues which are contrary to code which are routinely overlooked by ESA inspectors. Typical example is a double tap of 16 gauge wire from door bell double tapped with solid 14 gauge wire on a breaker only rated for one conductor.

Another case the pvc conduit should not be fed underground to a main panel, yet the local ESA inspector approved the installation which included the conduit being brought in under grade to the panel in the basement.

We don't live in a perfect world and even though I would like to think we do, I know better than to say everything is perfect, even code officials turn a blind eye to issues.

The definitive test is the court of law, and even then you will have experts contradicting one another.

62. ## Re: Bunching Romex

Yes they would require additional derating Kristi. The "exposed" method and choice of material is likewise compromised.

The additional derating is required so as to maintain integrity and not melt, catch fire, vaporize, etc. the insulation and not overheat the conductors themselves should there be a maximum available fault current/short circuit exposure condition - it/they must maintain its/their integrity so that the protection system can respond; and additionally withstand the effects of the incredibly strong electomotive force in the circuit(s) during a maximum available fault current condition. This is also one of the many reasons why we restrain, clamp, etc. conductors, but require "slack"/work length at junctions, etc.; secure equipment; brace busses, main circuit breakers on service equipment, back fed breakers, etc. Path of return to source means the utility transformer.

SCCR (short circuit current ratings), AIC (available interrupting current) ratings or AIR (ampere interruption rating) and temperature ratings are important considerations along with the available fault current. (This is also why those "wire nuts" on your little old lady's service drop are so dangerous and a major red flag for your insurance surveys as well).

AIC applies to protective interrupting devices such as circuit breakers and fuses. The unit of measure for AIC is Amps RMS Symmetrical. typically in range of 5K to 200K amps describes the maximum fault current that the protective device can clear safely without welding closed or causing damage to equipment or personnel.

SCCR applies to complete pieces of equipment or components such as racks, cabinets, or subassemblies such as busses, etc.. The unit of meaure is also Amps RMS Symmetrical and describes the maximum fault current that the euqipment can withstand safely or the maximum available fault current of the feeder to which the equipment can be safely connected.

Available fault current, AIC ratings of protective devices, and SCCR of switchgear and utilization equipment must be coordinated from the utility transformer to the last outlet in the system.

At every point in the system, the available fault current can be calculated, and the engineer must insure that it does not exceed the AIC of protective devices or SCCR of equipment installed at that point.
The engineer has tools availble for limiting available fault current, the most common being wire length. The impedance of a wire run means that the longer the run, the lower the availble fault current at the end of the wire. Other devices such as electronic current limiting circuit breakes and current limiting fuses have a characteristic known as let-through current. These devices can be used to limit fault current when equipment with a low SCCR must be connected to a source of high available fault current, and no long run of wire is possible.

It is interesting to note that fault current translates into incredibly strong electromotive force in the event of a short circuit. This is the reason that one will often hear statements like "that bus bar is braced for 100K amps". Not only does the bus bar have to avoid melting in the presence of a short circuit, it also has to be restrained so that it does not RIP OFF ITS MOUNTS when the fault occurs.

Its not just the every day utilitzation alone that is considered by the requirements of the code, it is also the easily foreseen albiet rare events that for safety protection of property and preservation of LIFE, must be designed for.

HTH.

P.S. Keep in mind that things are quite different in Canada, especially in the province of Ontario. Legal issues, code issues, goverement owned utilities, and the Electrical Safety Authority are entities and constructions that are completely different from what we have here in the United States, even their form of government is quite different, most especially their court system and common law/strict liability issues.

Last edited by H.G. Watson, Sr.; 11-18-2011 at 05:51 PM.

63. ## Re: Bunching Romex

"Variance" - that's the word I was looking for. Raymond, I think you misinterpret me a little. I was saying that there are some conditions under which code may not apply because the circumstances don't merit it...and then a variance, after due consideration, is warranted. There may also be parts of a code that are outdated because new evidence or materials or whatever determines that they are unnecessary. My problem is with people who ignore parts of code because they personally don't think it's valid although the evidence says otherwise.

Bundling can be a hazard. That's been demonstrated. Maybe it's not an issue the majority of the time because the circuits aren't used continuously or at high enough amperage to make a difference. But our electricity usage continues to grow, people leave their 4' TVs on 24/7, bake a turkey for 5 hours in an electric oven, run a bunch of electric space heaters, whatever...and if the NM in the middle of the bundle can't dissipate the heat it could be a problem. No one knows what demands will be placed on those cables in the future. Code is there for a reason, and it shouldn't be taken lightly.

EDIT: Above was posted without having seen HGW's post.

Sometimes I frankly have a little trouble absorbing your posts immediately, but some stuff sinks in and over time I can make sense of it all - and appreciate the detail you go into.
The additional derating is required so as to maintain integrity and not melt, catch fire, vaporize, etc. the insulation and not overheat the conductors themselves should there be a maximum available fault current/short circuit exposure condition
Based on what I've read through Googling, this isn't always the case. Even under some ordinary circumstances of continous loads, especially in warm areas like attics, as Jerry pointed out, or when a bundle has insulation or fire retardant foam around it, the cables can heat up enough to be damaged. No fault is required for a problem to arise.

Last edited by Kristi Silber; 11-18-2011 at 06:21 PM.

64. ## Re: Bunching Romex

Originally Posted by Kristi Silber
EDIT: Above was posted without having seen HGW's post.

Sometimes I frankly have a little trouble absorbing your posts immediately, but some stuff sinks in and over time I can make sense of it all - and appreciate the detail you go into.

Based on what I've read through Googling, this isn't always the case. Even under some ordinary circumstances of continous loads, especially in warm areas like attics, as Jerry pointed out, or when a bundle has insulation or fire retardant foam around it, the cables can heat up enough to be damaged. No fault is required for a problem to arise.
Ambient temperature is yet another derating "step" or consideration. Insulation contact - i.e. restriction of free air contact is yet another when applying for example NM or similar (such as UF cross-referenced) wiring methods. The "protection" if plastic (Sch 80) or metal, exposure to direct sunlight, are additional considerations. The installation location conditions - wet, damp, dry, exposed or covered wiring methods, etc. Stapling too tightly causing heat build-up under the staple, the list goes on.

I suggest you review some of the extensive discussions already present on this board as well, but if you're going to debate "the code" I suggest you learn some electrical theory first, then read the code itself. IOW read/study more, debate less.

There are a number of free "modules" and training materials available on such subject areas including electrical inspeciton available on the web, if you're truly interested in learning more.

65. ## Re: Bunching Romex

You are right that I should study more on my own. However, I have not debated anything in this thread that I don't understand. I was not debating your earlier point, merely pointing out that circumstances beyond those you described also come into play, just as you wrote in your latest post.

I'm here primarily to learn. Debating can itself be an education. I don't wish to refrain from discussion until I've read the whole NEC, nor do I think I should have to.

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