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Thread: 3 Cable Feeder

  1. #1
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    Default 3 Cable Feeder

    This is an office complex built in 80. 8 units in the complex, each with a seperate service disconnect (which I could not access) and distribution panels. Do you note the presence of three cable feeders, in particular if grounds have been installed in the distribution panels associated with newer circuits. Pics suck, I cant down load the good ones for some reason.

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    Default Re: 3 Cable Feeder

    Trying to get a good picture

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  3. #3
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    Default Re: 3 Cable Feeder

    Matt

    I think what you have there is metal conduit (EMT) serving as the equipment ground for the feeders. So they are 4 wire (3 + emt) not 3.


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    Default Re: 3 Cable Feeder

    What Roger said, I was thinking the same when I opened first pic of first post, but he's on a quicker connection than me and obviously a faster typer!

    Then I kept looking at the main locknut/bushing and kept asking myself, is that plastic?

    Then I kept trying to see better in the pics and wondered is this poly off a tsfrmr? But if I can't make out detail in your pics I'm lost because I'm no wiz with the photo editing or refining skills like you and Roger, and I'm just up for a late night nature call and snack.

    Short term memory is less than ideal even when fully awake, but these aren't all pics (5) of the same panel are they (fourth pic, or first of second post couldn't possibly be the same could it??? can't remember xxxx at this hour as a pan amongst them. Seems at least two or three had some tape and some damage to the insulation couldn't make out much but hmmm.

    80s were a tough period in changes in the code, so were the early 90s and its too late for this geezer to jump start the foggy brain cells, but I'm "hmmming" already and if I think about it too much I'll not get back to sleep easily.

    I'm counting seven in one pic. The mains disconnects should have been accessible, for the occupant or on-call management. Where was building management?

    I've forgotten now, whole building transfer or a commercial "condo"?

    Last edited by H.G. Watson, Sr.; 11-10-2010 at 11:31 PM.

  5. #5
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    Default Re: 3 Cable Feeder

    I have to go back today, I will take some better pics. The mains were on the exterior although I could not get the cover off, each unit had its own meter and I could not remove the dead from cover Didn't think of the metal conduit though, thanks.


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    Default Re: 3 Cable Feeder

    Matt, those are not cables, they are individual conductors.

    Cables are an assembly of conductors wrapped within an overall sheath or jacket. Conductors are installed in a raceway system like conduit or a trough.

    There is a locknut under the plastic bushing.


  7. #7
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    Here is what the disconnect looked like and neutral and grounds were sharing terminals is several panels. That's what threw me . I will take some more pics. Have to go back today and finish two more buildings. Wow the place was a dive

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    Default Re: 3 Cable Feeder

    Quote Originally Posted by mathew stouffer View Post
    This is an office complex built in 80. 8 units in the complex, each with a seperate service disconnect (which I could not access) and distribution panels. Do you note the presence of three cable feeders, in particular if grounds have been installed in the distribution panels associated with newer circuits. Pics suck, I cant down load the good ones for some reason.
    Matthew,

    Looks like they might be using the conduit to provide ground. Might need to bond the conduits as well as the grounding terminal block to ensure an adequate ground path.

    Don't you need to derate multiple conductors in a conduit?

    What happened to the cable insulation in the 3rd pic?

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    Default Re: 3 Cable Feeder

    Quote Originally Posted by Gunnar Alquist View Post
    Don't you need to derate multiple conductors in a conduit?
    Yes, for more than 3, and the neutral is not counted (a true neutral, not what is commonly called a neutral but is really just a grounded conductor).

    The best way to remember the neutral part is like this: more than 3 *current carrying* conductors, and a "neutral" only carries the unbalanced current from the two hot conductors, thus the lower phase current plus the unbalanced current on the neutral equal the current on the higher current phase conductor.

    A commonly called "neutral" which is really just a grounded conductor (i.e., 120 volt circuit) carries the full current the hot conductor carries, thus there are two conductors carrying the same current. Now put 2 120 volt circuits in the same raceway and you have 4 "current carrying conductors" and derating begins.

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  10. #10
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    Default Re: 3 Cable Feeder

    Quote Originally Posted by mathew stouffer View Post
    Here is what the disconnect looked like and neutral and grounds were sharing terminals is several panels. That's what threw me . I will take some more pics. Have to go back today and finish two more buildings. Wow the place was a dive
    Several other issues in the latest two pictures so not sure if you have those in mind to make note in your report... a few are ... the bare wire in the yellow wirenut with the two white grounded wires. Also looks like no bonding means is installed as would be wanted but a ground wire is connected to the neutral bus, open knockouts and so on...

    In your original post and photos there is a ungrounded hot conductor in a main lug that appears to have been really hot at one time as the insulation looks melted..looks like they wrapped electrical tape around the damaged part.


  11. #11
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    There were 26 offices and each panel was different. It was like a little treasure chest each time I removed the cover. Some had the neutrals bonded, some grounds and neutrals were sharing bars, some neutrals were isolated. THen in the final building, bam, all federal pacific panels. I have a head ache. Rec evaluation all panels. It was a nightmare.

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    Default Re: 3 Cable Feeder

    Any good informative web sites about FPE


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    Default Re: 3 Cable Feeder

    Quote Originally Posted by Jerry Peck View Post
    Yes, for more than 3, and the neutral is not counted (a true neutral, not what is commonly called a neutral but is really just a grounded conductor).
    Jerry,

    Thanks for the info. In the original post, the third pic is of the top of the interior of the panel. At the upper/left is what looks like two red, one purple and one white in a conduit. Candidate for derating?

    And who is the bald guy looking in the electrical panel?

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  14. #14
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    I have all my hair


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    Thanks for the info. In the original post, the third pic is of the top of the interior of the panel. At the upper/left is what looks like two red, one purple and one white in a conduit. Candidate for derating?
    Probably no. The two reds and white appear to be a multiwire branch circuit and the purple does not terminate on a breaker. I'm unclear as to where the purple terminates. The white wire if that is a multiwire would not be counted as per Jerrys description of a neutral earlier. If the panel had been wired to 2008 NEC that multiwire would need to be tied together to identify it. A plastic wire tie works well.
    Thing to remember is you derate according to the temp rating of the wire insulation. and also must consider the application. By that I mean if I'm derating 12 awg copper THHN/THWN dual rated wire in conduit in a dry location then I can use the 90C column (a THHN application) of table 310.16 ... that would be 30 amps. So using the deration factors as stated in table 310.15(b)(2)(a) I would need to have 10 #12's before it becomes a issue if I'm complying with 240.4 D for small conductors.

    If my application is a wet location and the wire is rated THWN (not THWN -2) then I would need to use the 75C column and start derating at 25 amps. In which case I could not have more than 6 current carrying #12's in a single raceway assuming no other conductors but those #12's and 240.4D. There are also other factors that effect derating calculations so it is not always as easy as above.

    Looking for a good reference for residential applications I didn't have much luck but I did find a good though somewhat lengthy article by the IAEI ..... that covers quite a few subjects including deration calculations

    Sizing Conductors for All Load Conditions | IAEI Magazine Online

    another related subject

    Wire Temperature Ratings and Terminations | IAEI Magazine Online



    And who is the bald guy looking in the electrical panel?
    Not Jerry .. the background terrain is wrong, not sure about the bald thing though ....probably is Scott Patterson ...


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    Default Re: 3 Cable Feeder

    Quote Originally Posted by Jerry Peck View Post
    Yes, for more than 3, and the neutral is not counted (a true neutral, not what is commonly called a neutral but is really just a grounded conductor).

    The best way to remember the neutral part is like this: more than 3 *current carrying* conductors, and a "neutral" only carries the unbalanced current from the two hot conductors, thus the lower phase current plus the unbalanced current on the neutral equal the current on the higher current phase conductor.

    A commonly called "neutral" which is really just a grounded conductor (i.e., 120 volt circuit) carries the full current the hot conductor carries, thus there are two conductors carrying the same current. Now put 2 120 volt circuits in the same raceway and you have 4 "current carrying conductors" and derating begins.
    Jerry-
    should we bring up that it also depends on if its a 4 wire,3 phase sytem?
    If you have 2 hots and 1 neutral in a conduit from a 3 phase 4 wire panel then you have 3 current carrying conductors in that conduit. 3 hots and 1 neutral in a conduit from the same panel and you still have 3 current carrying conductors. 2 hots and 1 neutral in a conduit from a 3 wire single phase panel you have 2 current carrying conductors.

    Now lets throw another wrench into the equation.....

    Should we discuss that if the majority of the loads are nonlinear then the neutral is considered current carrying regardless?
    In todays world of electronics you can almost always assume that the majority of the loads are nonlinear.


  17. #17
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    Quote Originally Posted by ken horak View Post
    Jerry-
    should we bring up that it also depends on if its a 4 wire,3 phase sytem?
    If you have 2 hots and 1 neutral in a conduit from a 3 phase 4 wire panel then you have 3 current carrying conductors in that conduit. 3 hots and 1 neutral in a conduit from the same panel and you still have 3 current carrying conductors. 2 hots and 1 neutral in a conduit from a 3 wire single phase panel you have 2 current carrying conductors.

    Now lets throw another wrench into the equation.....

    Should we discuss that if the majority of the loads are nonlinear then the neutral is considered current carrying regardless?
    In todays world of electronics you can almost always assume that the majority of the loads are nonlinear.
    I would agree Ken that there really is no reason for an HI to concern himself with conductor derating issues in residential settings..

    I think you would be better served to just get a good idea about conduit fills, bundling, and more tangible issues of that nature and if that looks suspicious ..verify.. then make note in your report. It would be up to an electrician evaluating the panel to worry about any derating problems IMO.

    Derating wires in conduit in single family homes for non linear load is not something I think you would likely ever come across. Maybe some multifamily but not very often IMO. Larger complexes like high rise apartments or the like may have some non-linear lighting to consider ...but would you be expected to have that knowledge as a inspector evaluating the property??

    As for discussing Gunnars question about derating conductors .. understanding the method and rules for doing so can only add to ones professional knowledge.

    As you have shown it is a rather broad area of understanding and is not a 'simple ' process in many situations though those are mostly commercial or industrial in nature.

    Most of the derating issues in residential center around high ambients more so than the number of current carrying conductors in conduit.

    Understanding 240.4D and the ambients on table 310.16 and how many conductors of a certain size or mix of sizes in the small conductor range of 14 awg to 10 awg that will cause you to have to down size your OCPD will likely get you through just about any issue in residential single or multifamily.

    Again other than discussing for your personal interest IMO it is out of the scope for a HI to concern himself with in any report in a residential setting..

    Last edited by Roger Frazee; 11-12-2010 at 01:07 PM.

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    Default Re: 3 Cable Feeder

    I would agree Roger, EXCEPT this is not a residential setting. 8-unit OFFICE condos.

    That's why I brought up the subject of poly-phase in the wee-hours.


  19. #19
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    Default Re: 3 Cable Feeder

    Quote Originally Posted by H.G. Watson, Sr. View Post
    I would agree Roger, EXCEPT this is not a residential setting. 8-unit OFFICE condos.

    That's why I brought up the subject of poly-phase in the wee-hours.
    Yes quite true.

    Anyway thanks for getting me back on track as to the situation at hand. It does make a difference.

    Still though would an inspector evaluating a commercial property .. (like offices in this situation) .. for insurance or a buyer .. concern himself/herself with conductor derating outside of ambient considerations?


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    Default Re: 3 Cable Feeder

    Roger-
    I was pointing out that when it comes to derating due to conduit fill, or number of conductors in a cable, it's not as simple as some seem to think it is.

    I agree it is out of the scope of 99% of HI's.

    I do have a firm grasp( knowledge) on the NEC by the way.


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    Default Re: 3 Cable Feeder

    Quote Originally Posted by Roger Frazee View Post
    Not Jerry .. the background terrain is wrong, not sure about the bald thing though ....probably is Scott Patterson ...
    Roger,

    Thanks. the derating thing has always been a bit of a mystery to me. I understood some of the basics, but the details were a bit foggy. Now I have some useful information.

    On my computer (at least) there is some bald guy with a flashlight peering at an electrical panel. The house seems to have a pretty nice view. Maybe not everyone gets the same ads that I do.

    I figure that I have 90% of my hair (if I can count the stuff that is cascading down my back). Otherwise, I would say 85%.

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  22. #22
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    Default Re: 3 Cable Feeder

    Roger-
    I was pointing out that when it comes to derating due to conduit fill, or number of conductors in a cable, it's not as simple as some seem to think it is.

    I agree it is out of the scope of 99% of HI's.
    Actually that is the point I thought you were making

    I do have a firm grasp( knowledge) on the NEC by the way.
    Yes you do and I have learned more than a thing or two about the NEC from your posts.
    I apologize if my reply appeared to be implying otherwise. I don't consider myself an NEC expert by any stretch of the imagination. Basically I was just trying to reply to you that it is indeed 'as you mentioned ' not a simple subject.

    Anyway be sure that I will not make a condescending reply about your knowledge of the NEC. I'll try to do a better job in the future communicating on the forum.

    roger


  23. #23
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    Default Re: 3 Cable Feeder

    Thanks. the derating thing has always been a bit of a mystery to me. I understood some of the basics, but the details were a bit foggy. Now I have some useful information.
    Your welcome and it never hurts to improve ones knowledge, if your really wanting to have a good resource to learn electrical consider subscibing to ECM Magazine and they also are online. Not a better source of useful electrical articles IMO.


    On my computer (at least) there is some bald guy with a flashlight peering at an electrical panel. The house seems to have a pretty nice view. Maybe not everyone gets the same ads that I do.
    Yeah I see the same ... always thought the person looks like Scott. I think that the guy in the ad may be taller though ...

    I figure that I have 90% of my hair (if I can count the stuff that is cascading down my back). Otherwise, I would say 85%.
    You don't know how much I can relate to that statement....


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    Default Re: 3 Cable Feeder

    Quote Originally Posted by Roger Frazee View Post
    I would agree Ken that there really is no reason for an HI to concern himself with conductor derating issues in residential settings..
    I disagree.

    There are MANY (many, many, many, etc.) installations in residential structures which were installed such as derating is required to be addressed.

    As to whether a home inspector should address it or not (that was specifically who you stated) then that answer would best be answered by the individual home inspector.

    When I did home inspections I called it out quite frequently, as did other home inspectors in the area where I was then - in fact we called it out so much that the municipal inspectors finally started addressing the issue.

    The problem is that many will apply the derating for the number of conductors from the ratings in the ampacity tables, which is the incorrect way to do it. (Hold your thought a moment and continue reading ... )

    FIRST ... before applying derating for the number of conductors one must FIRST apply the derating for ambient temperature. This includes conductors in the wall outside the thermal envelope (outside the insulation) and especially conductors which run through attics. If any part of the circuit conductor runs through an attic, for example, then the entire circuit conductor must first be derated for the ambient temperature of the attic during the hottest the attic will potentially get during the heat of summer.

    Only after derating from ambient is the derating for number of conductors applied, and that creates a very great potential for circuits having an ampacity which is derated to low for the standard breaker sizes used.

    Here is an example:Let's presume the circuit is 12-2 NM-B and runs up into, and down from, the attic. Let's further presume that the attic temperature during the hottest part of the year gets to 135 degrees F.

    The ambient derating for 135 degrees F falls between 132 degrees F and 140 degrees F, which has a derating factor of 0.71 for 90 degree C rated conductors.

    Those same 90 degree C rated conductors have an beginning ampacity for derating of 30 amps. Thus we derate that 30 amps by 0.71 to 21.3 amps.

    Now, for this example, let us further presume there are two 12-2 NM-B cables run together in a nice neat bundle or where spacing is not maintained (if is likely there are more than just those two cables nice and neatly run together, but two cables will serve for this example). We then apply the derating for 4 current carrying conductors in a raceway, or cable, or bundled, or where spacing is not maintained, and that derating factor is 80%.

    The ambient derated ampacity for this example was 21.3 amps, and we not further derate those conductors by the number of conductors derating factor of 80% ... 21.3 x 80% = 17.04 amps.

    Now we know that we are allowed to increase the overcurrent device to the next higher standard rating, which would be 20 amps ... except that those circuits do not meet the strict limitations of circuits allowed to have their overcurrent protection increased to the next higher standard rating as those are multioutlet circuits, as are virtually all circuits in a dwelling unit (except for a range, dryer, etc., meaning almost any circuit on a 14-2 or 12-2 NM cable would be a multioutlet circuits - with very few exceptions). That means the overcurrent protection for that 12-2 NM-B would now need to be 15 amps.

    Now change that 12-2 NM-B to 14-2 NM-B and you get a real problem:25 amps x 0.71 = 17.75 amps derated for ambient x 80% = 14.2 amps derated for 4 conductors in a raceway, cable, bundle, lack of maintaining spacing ... and no ability to install the next higher standard overcurrent device rating of 15 amps. That means you are not allowed to use 14-2 NM-B for a 15 amp circuit, you must use 12-2 NM-B for that circuit ... AND ... it means that 12-2 NM-B is not allowed to be used for a 20 amp circuit, you would need to use 10-2 for that 20 amp circuit.

    I run into that ALL THE TIME in new construction where the electricians try to be all nice and neat and staple two 14-2 NM-B cables under a staple and run them up a stud from a switch through the top plate and into the attic (or down from the attic) ... they now have 4 current carrying conductors without maintaining spacing for greater than 24" (more like 4 feet or more) and which need derating for number of conductors after derating for the attic ambient temperature.

    That is why they came out with those new (several years ago) straps which mount to the studs and hold the NM cables out from the stud separated from each other ... now if we could only get electricians to use those ...

    (H. G., I had the same formatting problem you get now and then where everything runs together. I solved it by clicking on 'Advanced' while in edit mode and added the line breaks there - that solved the problem, may it will solve it for you the next time it happens?)

    Last edited by Jerry Peck; 11-12-2010 at 08:10 PM.
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  25. #25
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    Default Re: 3 Cable Feeder

    I was certainly refering to HI's but in my career I never had a HI report in front of me that cited a derating issue other than bundling. In fact I never or can't remember an AHJ providing any guidelines to the electrical community for residential attic temperatures to be used in conductor derating calculations.

    It was and continues to be a controversial subject. The only resource I know of for an recognized source for ambients is the ASHRAE tables and they do not address attic temperatures only outside temps or conduit on rooftops. The NEC doesn't define ambient temperatures and only shows a FPN refering you to ASHRAE in 310.15b2c. So if you can pin down an attic temperature for me I'm all ears....

    I'm not saying that you should not factor a higher temperature in for an attic but just what temperature do you use?? I've never seen a table of attic temperatures for US cities to use for deration of nm cables or wire in conduits installed in attics.. so do I use the ASHRAE max. temp for Daytona Beach of 102 F outside for the inside attic?? Or do I use your example temperature of 140F..?

    Anyway I'm not disputing the need to design your conductors as an installer to take into account high attic temperatures. I'm simply saying that an HI in my opinion regardless of knowledge does not need to concern himself with attic temps or too many current carrying wires in a conduit. If you see wires bundled in attics just call that out and the need to determine what the heck the attic temp is going to be goes away. Fix the bundling and your good to go. If it gets more complicated than that you guys down in Florida need to have some local amendments stating no 14 awg in attics or something because the attic temperature rise lowers the ampacity below 15 amps. If you as an electrician bundle a bunch of 12 or 14's then shame on you ... you should know better. But as you said you see it all the time.

    So what I'm saying Jerry is as an HI you should call out bundling no matter where it is located...a tangible issue. I have seen it lead to wires discoloring from heat generated from operating loads in all the cables. It's rare ... very rare ...extremely rare ... so much so I can't recall bundling to ever causing a fire in my area but none the less it is a concern.
    In my previous reply I specifically mentioned that the HI should concern himself with ambient derations and bundling not get into how many current carrying wires are in a conduit.

    Now I would agree if your an HI and hold a masters license or any electrical license for that matter and are knowledgeable in the deration of conductors in all situations and have a command of the subject then I see no reason to not put that knowledge to work. It would be a bonus IMO to who hired you. I think this is what you mean by "it depends on the home inspector".

    I run into that ALL THE TIME in new construction where the electricians try to be all nice and neat and staple two 14-2 NM-B cables under a staple and run them up a stud from a switch through the top plate and into the attic (or down from the attic) ... they now have 4 current carrying conductors without maintaining spacing for greater than 24" (more like 4 feet or more) and which need derating for number of conductors after derating for the attic ambient temperature.
    In all the years I worked this was never an issue nor enforced. I will concede that it is in the NEC and you could call it out during an inspection. I also realize that what used to be then .. may not be today..... Frankly if there was really a danger in the situation you describe thousands of houses would be burning down... but I have to admit we are worried about the one that might...

    Last edited by Roger Frazee; 11-13-2010 at 12:48 AM.

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    Default Re: 3 Cable Feeder

    Quote Originally Posted by Roger Frazee View Post
    In fact I never or can't remember an AHJ providing any guidelines to the electrical community for residential attic temperatures to be used in conductor derating calculations.

    It was and continues to be a controversial subject. The only resource I know of for an recognized source for ambients is the ASHRAE tables and they do not address attic temperatures only outside temps or conduit on rooftops. The NEC doesn't define ambient temperatures and only shows a FPN refering you to ASHRAE in 310.15b2c. So if you can pin down an attic temperature for me I'm all ears....

    Roger,

    Without further guidance from the NEC on temperatures, I refer to what it says ... ... "Table 310.16 Allowable Ampacities of Insulated Conductors Rated 0 Through 2000 Volts, 60C Through 90C (140F Through 194F), Not More Than Three Current-Carrying Conductors in Raceway, Cable, or Earth (Directly Buried), Based on Ambient Temperature of 30C (86F)", which means that a known attic temperature above that base ambient is subject to derating based on the ranges for derating from "CORRECTION FACTORS For ambient temperatures other than 30C (86F), multiply the allowable ampacities shown above by the appropriate factor shown below.", and I select the appropriate factor shown below for the ambient temperature I know of in the attic.

    When I was in South Florida, I knew of attic temperatures in the 132-140 degree F range (basically tile roofs), and some in the 141 to 158 degree F range (basically dark composition shingles), and I do not recall any 123 to 131 degree F or lower unless the attics were of the sealed, unvented, types with the insulation sprayed on the underside of the roof sheathing.

    The NEC does recognize derating for ambient, and does direct the user to derate for ambient higher than the range the conductor ampacity is listed for (86 degrees F), and thus I do that. I do not get any negative feed back from the contractors because they all recognize that the attics are so much hotter. I do, however, get complaints that there is no need to derate for bundling and lack of maintaining spacing because "NO ONE ELSE DOES THAT" ... as though that makes the practice acceptable.

    If only one derating were to be applied, there typically is no problem.

    However, getting back to ambient derating ... ... that is why NM became NM-B with the 90 degree C insulation ... so that derating for ambient in the attic would still allow the normal uses of 14-2, 12-2, 10-2 to be used for 15, 20, and 30 amp circuits.

    Thus, the only problem left is curing the installation problem of bundling and lack of maintaining spacing. If those installation practices were changed to reflect the proper installation of the NM cables, then derating would have no negative effect as NM-B was created for that purpose, and it would serve that purpose well as long as no derating for number of conductors is necessary.

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  27. #27
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    Default Re: 3 Cable Feeder

    Yes I would agree with that analysis and I didn't mean to come across as a negative attitude about taking deration of conductors in attics as non-important. I was just saying that in my career we never really worried about attic temperatures above our local ambient. Bundling was common as we are defining it here.

    FWIW in the latter years of my working career 2004 to 2007 the issue of deration and bundling did become more and more an issue with inspectors. And I think it is because there is much more information available from testing labs that this issue of derating and bundling in residential applications was more serious than we ever imagined. The concensus was in my area that residential loads were never such that a wire would overheat in an attic bundled or not.. So we just never worried about it and probably never installed nm bundled to the point we thought there was a hazard ... unfortunately it was a more serious deal that we expected.

    Of course the issue is whether or not an HI should concern himself with all this and I suppose my earlier opinion did sort of sound like a 'stick in the mud' approach. I do think that bundling should be a concern anywhere in the dwelling and HI's should call that out. That said .. I shunder to think the work involved to seperate all the doubled nm cables in attics and inside walls in old construction. The danger just isn't there IMO to give it a high priority.. Now that is a very limited opinion as I cannot speak for homes in Arizona or other states where they have extremely high attic temperatures ...and I'm not sure how the electricains have handled those installations over the years but likely just like most of the country they didn't give it much thought..

    I do think the solution is what is happening now ...better awareness of the potential problem .. so that electricians will install the wiring with proper design for high ambients and inspectors that enforce it in new construction. Problem for the most part then goes away for future construction.

    So I do agree about attics and bundling but my point earlier was I do not think an HI/property inspector should start calculating wires in conduit and determining if the number of current carrying wires is going to create a heat problem in residential applications or commercial... I wonder how many HI's in Chicago do this ?? It would be interesting to know.

    Yes I understand table 310.16 and and the ambient factors ... it really is a simple thing to determine the ambient correction factor in an attic for your local area if you are inclined to... but as you said get rid of the bundling and there is no problem. I was simply saying earlier that it was not something we were under instruction to comply. You did not get tagged for bundling a couple nm cables in the attic or anywhere else.

    Also thanks for the information on NM_B I wasn't aware of that.

    Anyway I do keep up on things and I have a very good library of downloaded articles on many subjects so I can stay educated to the changing times... this is the best one I have on tests for temperature rise for bundling and wires in conduit for the subject we are discussing ... maybe you will find it of interest if you don't have it.

    Ambient Temperature Ampacity Corrections for Cable Bundling and Direct Solar Exposure | IAEI Magazine Online

    And one that is somewhat related but very little information is available on this subject for temperature limits of non-metallic raceway.

    http://www.carlon.com/Codes_Standard...s_Raceways.pdf



    To add .. when I was working for Ford in the assembly plant (lots of conduit) it was a very big deal making sure you were in compliance with derating ampacities of conductors. So I've been at both ends of the spectrum

    Last edited by Roger Frazee; 11-13-2010 at 02:38 PM. Reason: just something to do

  28. #28
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    Default Re: 3 Cable Feeder

    Quote Originally Posted by Roger Frazee View Post
    I do think the solution is what is happening now ...better awareness of the potential problem .. so that electricians will install the wiring with proper design for high ambients and inspectors that enforce it in new construction. Problem for the most part then goes away for future construction.

    I fully agree with that - have to start doing it right at some point in time, the sooner the better, and age will take of the problems in its own way ... and better information is a great teacher and eye opener ... 20 years ago and back I was not paying much attention to bundling, but since then (the early 1990s to today) I have paid more and more attention to it and learned more and more about it, and that is good (but not good for the contractors I am inspecting and which have to correct their work).

    Thank you for the two links, they do contain good information ... see ... learning even more (those poor electrical contractors will really be sorry now ... ).

    Did you see the IAEI article a few years back where they showed photos of probably 10-15 NM cables stuffed through a bored hole through a double top plate, and while it was not anywhere near close to the 24" limitation it really created a fire safety problem? Was similar to the bundling experiment in the link you posted.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  29. #29
    Roger Frazee's Avatar
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    Default Re: 3 Cable Feeder

    Did you see the IAEI article a few years back where they showed photos of probably 10-15 NM cables stuffed through a bored hole through a double top plate, and while it was not anywhere near close to the 24" limitation it really created a fire safety problem? Was similar to the bundling experiment in the link you posted.
    I don't think I have. I'll see if maybe I can find it. I have a picture of bundling in my folks home built in the early 90's. I'll post it in a few days You will find it interesting.


  30. #30
    John Steinke's Avatar
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    Default Re: 3 Cable Feeder

    I'd love to comment - but just what is the topic? This thread has gone all over the place, with at least two complete sea changes from the OP!

    Might I suggest starting different threads for tangents such as FPE and cable fill?

    As for the OP .... sure looks like the ground is missing. I'd want to verify that the neutral is not bonded to the case.

    I can't set a year on specific code language, but using the conduit as the ground for a feeder - as oposed to for a branch circuit- has been avoided at least since the 80's. (And, BTW, the 80's are neither 'long ago' nor 'old' )

    Assuming that this panel is fed by it's own breaker, there in no reason to apply the 'six throws' rule.


  31. #31
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    Default Re: 3 Cable Feeder

    I'd love to comment - but just what is the topic? This thread has gone all over the place, with at least two complete sea changes from the OP!

    Might I suggest starting different threads for tangents such as FPE and cable fill?

    As for the OP .... sure looks like the ground is missing. I'd want to verify that the neutral is not bonded to the case.

    I can't set a year on specific code language, but using the conduit as the ground for a feeder - as oposed to for a branch circuit- has been avoided at least since the 80's. (And, BTW, the 80's are neither 'long ago' nor 'old' )

    Assuming that this panel is fed by it's own breaker, there in no reason to apply the 'six throws' rule.
    These are conductors in conduit not cables, J.S.!

    Oh, YES there is, the six throw rule DOES apply - the OP has ALREADY indicated non-accessiblity to the disconnects/ocpds for ALL these feeders!

    If the disconnect is NOT ACCESSIBLE during all periods of occupancy either via on-site 24/7 managment presence control or the individual occupancies has/have some means of access (key, means to gain ready access), there IS.

    These are OTHER THAN residential occupancy CONDOS - commercial or otherwise occpancies Mat has followed up with explanation that there are 8 "Units" containing 26 offices! That's potentially at least 26 separate and distinct occupancies and up to at least 8 intervening "management" controll/owner entities them, (possibily under a singular master/umbrella condo entity?!?! Mat has pictured at least three panels with N & G on the same bar. Mat has pictured at least one panel with two indicated wirenutted to a bare solid copper conductor.

    And if Mathew Stouffer, the OP of this thread topic wants to further take the thread discussion down the FPE road since he's subsequently found same, and ask for a FPE web resource, that's HIS perogative, its HIS topic thread.

    By the way, the field applied REQUIRED warning/danger labeling on the exterior of the equipment - and upon the equipment at the exterior of the building are missing or obscured by paint for this NON-RESIDENTIAL OCCUPANCY.

    Apparently 20-30 years is like yesterday to you, as you are so often stuck in a rut of six plus cycles ago. As far as feeders and main power feeders, bonding, etc. yep its old as far as "rules", numerous modifications (not just "maintenance" of original installations!, and standards for safety.

    Substituting plastic condulets and pull boxes for former conductive metallic conduit makes a huge difference, that's not just maintenance or repair on the exterior.

    Last edited by H.G. Watson, Sr.; 11-14-2010 at 09:58 AM.

  32. #32
    Roger Frazee's Avatar
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    Default Re: 3 Cable Feeder

    I'd love to comment - but just what is the topic? This thread has gone all over the place, with at least two complete sea changes from the OP!
    Not really ... his specific questions were answered. another member asked a question about the deration of conductors in a raceway in one of the panels posted by Matt and we discussed that in length.

    Might I suggest starting different threads for tangents such as FPE and cable fill?
    Never talked about cable fill and the FPE question was Matt ( the original OP) so if he wants a new thread he needs to start one.

    As for the OP .... sure looks like the ground is missing. I'd want to verify that the neutral is not bonded to the case.
    If the ground is missing I'd want to verify that the neutral was bonded to the case until a ground can be installed.

    But the ground is not missing they are using metal conduit ... which by the way provides one heck of a good and effective ground path.

    I can't set a year on specific code language, but using the conduit as the ground for a feeder - as oposed to for a branch circuit- has been avoided at least since the 80's. (And, BTW, the 80's are neither 'long ago' nor 'old' )
    Can you send me a case of what your drinking .....

    Assuming that this panel is fed by it's own breaker, there in no reason to apply the 'six throws' rule.
    What Hg said

    I do admit the biggest turn in direction here was my off the path referencing of RESIDENTIAL PROPERTY when this is a COMMERCIAL OFFICE PROPERTY...

    You will notice, if you read the thread , that HG quickly brought that to my attention...


  33. #33
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    Default Re: 3 Cable Feeder

    For anyone interested -

    Here is a good article on FPE Panels......

    Where are you guys from - do you ever use the phrase - Sub Panel, as opposed to distribution panel?

    Ihttp://www.prestigeelectric.net/downloads/fpe-panels-hazard.pdf

    Last edited by matt faust; 11-14-2010 at 08:58 PM. Reason: correcting url
    Matt Faust
    Real Estate Inspector

  34. #34
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    Default Re: 3 Cable Feeder

    "I can't set a year on specific code language, but using the conduit as the ground for a feeder - as oposed to for a branch circuit- has been avoided at least since the 80's. (And, BTW, the 80's are neither 'long ago' nor 'old' )"

    WOW - with all due respect...............

    Putting aside the rather bazaar comment above -

    Equipment Grounding Conductors - EGC
    Grounding Electrode Conductors - GEC
    Grounding Electrodes
    Grounded Conductors
    Ground Bars - Neutral Bars
    Bonding - Bonded............
    Bonding Jumpers

    Terminology is never more important than when we are talking about Grounding.
    While I see a lot of knowledgeable information on this thread,
    Seems that there are a lot of abbreviated and slang terms which confuse the subject.

    Matt Faust
    Real Estate Inspector

  35. #35
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    Default Re: 3 Cable Feeder

    I can't set a year on specific code language, but using the conduit as the ground for a feeder - as oposed to for a branch circuit- has been avoided at least since the 80's. (And, BTW, the 80's are neither 'long ago' nor 'old' )

    Definition of Feeder:

    Feeder: All circuit conductors between the service equipment,the source of of a seperarately derived system,or other power supply source and the final branch circuit overcurrent device

    Now From the 2008 NEC
    Article 250.118

    250.118 Types of Equipment Grounding Conductors.

    The equipment grounding conductor run with or enclosing the circuit conductors shall be one or more or a combination of the following:

    (1) A copper, aluminum, or copper-clad aluminum conductor. This conductor shall be solid or stranded; insulated, covered, or bare; and in the form of a wire or a busbar of any shape.

    (2) Rigid metal conduit.

    (3) Intermediate metal conduit.

    (4) Electrical metallic tubing.

    (5) Listed flexible metal conduit meeting all the following conditions:

    a. The conduit is terminated in listed fittings.

    b. The circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.

    c. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground return path does not exceed 1.8 m (6 ft).

    d. Where used to connect equipment where flexibility is necessary after installation, an equipment grounding conductor shall be installed.

    (6) Listed liquidtight flexible metal conduit meeting all the following conditions:

    a. The conduit is terminated in listed fittings.

    b. For metric designators 12 through 16 (trade sizes 3/8 through 1/2), the circuit conductors contained in the conduit are protected by overcurrent devices rated at 20 amperes or less.

    c. For metric designators 21 through 35 (trade sizes3/4 through 11/4), the circuit conductors contained in the conduit are protected by overcurrent devices rated not more than 60 amperes and there is no flexible metal conduit, flexible metallic tubing, or liquidtight flexible metal conduit in trade sizes metric designators 12 through 16 (trade sizes 3/8 through1/2 ) in the grounding path.

    d. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground return path does not exceed 1.8 m (6 ft).

    e. Where used to connect equipment where flexibility is necessary after installation, an equipment grounding conductor shall be installed.

    (7) Flexible metallic tubing where the tubing is terminated in listed fittings and meeting the following conditions:

    a. The circuit conductors contained in the tubing are protected by overcurrent devices rated at 20 amperes or less.

    b. The combined length of flexible metal conduit and flexible metallic tubing and liquidtight flexible metal conduit in the same ground return path does not exceed 1.8 m (6 ft).

    (8) Armor of Type AC cable as provided in 320.108.

    (9) The copper sheath of mineral-insulated, metal-sheathed cable.

    (10) Type MC cable where listed and identified for grounding in accordance with the following:

    a. The combined metallic sheath and grounding conductor of interlocked metal tape–type MC cable

    b. The metallic sheath or the combined metallic sheath and grounding conductors of the smooth or corrugated tube-type MC cable

    (11) Cable trays as permitted in 392.3 and 392.7.

    (12) Cablebus framework as permitted in 370.3.

    (13) Other listed electrically continuous metal raceways and listed auxiliary gutters.


  36. #36

    Default Re: 3 Cable Feeder

    I see no ground comming in at the left bar, also at the left of the panel a hole is punched in and this shold be covered, WHY you say? if a fire is started in the panel it could be spread throught the house. (per code).


  37. #37
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    Default Re: 3 Cable Feeder

    Quote Originally Posted by Roger Frazee View Post
    Yes quite true.

    Anyway thanks for getting me back on track as to the situation at hand. It does make a difference.

    Still though would an inspector evaluating a commercial property .. (like offices in this situation) .. for insurance or a buyer .. concern himself/herself with conductor derating outside of ambient considerations?
    Oh yes, especially with a multi-occupancy building with common entrance point and shared or common gutters/wiring paths such as a commercial/office or industrial condo.

    Load diversity can get dicey, lets say suite one is out fit as a medical imaging center, and suite two is a computer repair shop, suite three is a seattle sutton distribution office (prepared food for weekly delivery usually lots of refrigeration and freezers) and suite five is a metal sculpter's art studio (welding), and the suite in the middle is a quick Printer (not just copying and bindery), while the suites upstairs frontage host a telemarketer and a dentist's office.


  38. #38
    Roger Frazee's Avatar
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    Default Re: 3 Cable Feeder

    Quote Originally Posted by H.G. Watson, Sr. View Post
    Oh yes, especially with a multi-occupancy building with common entrance point and shared or common gutters/wiring paths such as a commercial/office or industrial condo.

    Load diversity can get dicey, lets say suite one is out fit as a medical imaging center, and suite two is a computer repair shop, suite three is a seattle sutton distribution office (prepared food for weekly delivery usually lots of refrigeration and freezers) and suite five is a metal sculpter's art studio (welding), and the suite in the middle is a quick Printer (not just copying and bindery), while the suites upstairs frontage host a telemarketer and a dentist's office.
    Yes I see your point. I didn't realize that a property inspector would concern himself with those issues. I wrongly thought that they would probably contract a electrical contractor to perform that inspection and evaluation if it was required.


  39. #39
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    Default Re: 3 Cable Feeder

    Roger,

    Of course a deferal and review by a Master Electrician or an Engineer would be recommended if a CONCERN was noted, detected, determined by an inspection.

    The statement you made included a phrase which included a reference as to an Inspector being CONCERNED

    I indicated that YES and inspector would rightfully be CONCERNED, and why.

    Not that an inspector would be performing engineering calculations nor applying derating, ampacity adjustments, etc.

    Simply identifying that a condition warrants a deferral for a full evaluation, and making the correct CALL, so to speak.

    P.S. not shouting, for whatever reason the bold and underlining isn't working as I compose this and I'm not inclined to edit/re-edit and waste my evening after a quick read. there is NO shouting in the "tone" of this post. Highlighting your question/statement regards one inpsecting non-residential property being "concerned" regards to required adjustments to ampacity for current carrying conductors, and the allowed ampacity for a certain inspected condition, being in conflict as installed.


  40. #40
    mathew stouffer's Avatar
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    Default Re: 3 Cable Feeder

    Each panel was a mess. Some had boned neutrals, neutrals and grounds sharing bars, no grounds, conduit housing the feeders was plastic and some was metal, and of course the FPE. I will keep you posted, the electrician is heading over next week. Can't wait to see the bid on this one. It's a bank owned POS, 24 units built in 1980. Any guesses


  41. #41
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    Default Re: 3 Cable Feeder

    Just slipping in a quick note. Don't forget to look for the 'bonding' of metallic service raceways, (ahead of service disconnecting means).
    Since in almost all cases we are just bonding the raceway,... it only is required to be bonded on one end. If it is meant to be a path, then bonding on both ends would be required.

    OK, not a quick note after all,....... If a bonding locknut is utilized, the set-screw should contact the enclosure and not just a punch ring,
    IMO. Also, over 250 volts would require bonding if punch rings are present. I could of just started a new thread, oops


  42. #42
    Roger Frazee's Avatar
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    Default Re: 3 Cable Feeder

    Quote Originally Posted by H.G. Watson, Sr. View Post
    Roger,

    Of course a deferal and review by a Master Electrician or an Engineer would be recommended if a CONCERN was noted, detected, determined by an inspection.

    The statement you made included a phrase which included a reference as to an Inspector being CONCERNED

    I indicated that YES and inspector would rightfully be CONCERNED, and why.

    Not that an inspector would be performing engineering calculations nor applying derating, ampacity adjustments, etc.

    Simply identifying that a condition warrants a deferral for a full evaluation, and making the correct CALL, so to speak.

    P.S. not shouting, for whatever reason the bold and underlining isn't working as I compose this and I'm not inclined to edit/re-edit and waste my evening after a quick read. there is NO shouting in the "tone" of this post. Highlighting your question/statement regards one inpsecting non-residential property being "concerned" regards to required adjustments to ampacity for current carrying conductors, and the allowed ampacity for a certain inspected condition, being in conflict as installed.
    OK my ???? are now answered.

    Sorry I'm not the best communicator with the keyboard.

    Your explanation is very straight forward. I actually was "trying" to ask if the 'inspector' would point out in his report that there appears to be be a need to evaluate for deration for wiring in the building raceways .... not actually make the calculations.. and at that point defer to an electrical contractor, engineer etc..

    PS ... that other stuff doesn't bother me at all ...don't worry about it ... appreciate what your saying though ...

    Thanks


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