Thread: REVISIT DOUBLE TAPPED NEUTRAL WIRES

HEY ALL

i know this has been discussed a million times, but came across this sieman panel with about six open tight down screws ,yet they double tapped most neutrals. read the panel info and i can't see where sieman says ok. wrote it up as a safety hazard and have repaired by licenced electrician. i do this every time..what yee say

charlie

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It's wrong according to the IRC, the NEC, and undoubtedly the instructions on the panel itself.
I see this in over 90% of inspections, I'd guess.

I am sure your right but if they all go to the same bus bar whats the difference?

Charlie,

Hard to read in the photo, but if you look at the first photo of the label, where it says "SIEMENS" at the top, look right below that and you will see "Series E" and below that you will see "Neutral Bar Wire Size" and below that you will the allowable wire sizes, and you will also note that none of them say two wires, they are all single listings of sizes.

Originally Posted by Mark Aakjar

I am sure your right but if they all go to the same bus bar whats the difference?

There is a risk of one of those neutrals being loose, less tight than the other.

Originally Posted by John Kogel

There is a risk of one of those neutrals being loose, less tight than the other.

If that was the issue they wouldn't allow 2 or 3 wires and mixed sizes on ground terminations. The issue is a neutral being removed (you know, loosen the screw and pull the wire out - for whatever reason) and the other neutral comes along. It's now a hot wire if any loads are present and has now possibly placed higher voltage on one side of a multi wire circuit.

For what it's worth, 3 wires stay in a buss bar pretty well if the screw is torqued properly. Putting that white stuff on the wires doesn't change that. Also keep in mind that a stranded conductor is permitted in almost all terminations in a panel, and it's a bunch of smaller wires.

It's really a very simple answer: You can't put two (or more) conductors in the same terminal unless the manufacturer says you can.

Stranded conductors are in no way the same thing as having multiple conductors in the same terminal. That should be plainly obvious so as not to need stating. Further, Some manufacturers require stranded conductors to be tinned before placing in the terminal.

The NEC (or whatever the adopted code in your jurisdiction may be) controls the specifications for equipment to conform to the requirements for service and distribution, while the manufacturer controls how to properly install their conforming equipment.

Originally Posted by Corn Walker

Further, Some manufacturers require stranded conductors to be tinned before placing in the terminal.

While I agree with your stranded versus multiple solid comment ...

... I have no idea what you are referring to here as I have never heard of the above.

Who, what, where?

Tinned copper was done many decades ago, but that was because the copper and rubber compounds reacted together chemically ... it had nothing to do with the terminals.

Quote:

Originally Posted by Corn Walker
Further, Some manufacturers require stranded conductors to be tinned before placing in the terminal.

Jerry, in this case it means the strands be soldered together to simulate a solid wire, not each individual strand being tinned.

Originally Posted by Joe Asta

Jerry, in this case it means the strands be soldered together to simulate a solid wire, not each individual strand being tinned.

Which is not "tinned" and I have still never heard of that requirement.

Looking for someone to teach me about it by providing supporting documentation.

Quote:

Soldering Guide
Learn how to Solder

• Introduction and Overview
• Basic Soldering Tools

Tinning Components


Tinning

Tinning is the coating or the filling of wires or connector contacts with solder. Before you can solder two parts together, you must first tin both contacts. The purpose of tinning is not to form a mechanical linkage of the melted tinned solder coating, but to form a proper thermal linkage. This thermal linkage must be present in the contact between the soldering iron tip and the work piece. Heat is transferred through the small contact area between the soldering iron tip and the soldered component. By having a small amount of solder at the point of contact, the contact area is greatly increased. When you actually begin to solder, the iron tip will come in contact with both tinned components which improves the thermal linkage. This solder bridge that you form provides the proper thermal linkage required to assure the rapid transfer of heat into the work.
Wire Tinning

To tin a wire, apply the tip of your iron to the wire for a second or two, then apply the solder to the wire. The solder will quickly flow, and coat the tip of the wire, and if it’s stranded wire, the solder will flow into it, and fill the wire. If you put too much solder on and formed a little ball of solder at the end of the wire, you should snip the end off afterwards. If you overheat the wire, you will melt the insulation off, or cause it to shrink back, and expose more copper core than planned.
Once you have tinned both parts, you are ready to solder them together.

I pulled this off the web. I see this alot since we use ballasts that have push-in terminal blocks. If we use stranded wire, we dip the stripped end in a solder pot so that it can be inserted in the terminal block.


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Jerry, I'll search for the reference for you. But to be honest here, I don't recall if it was a distribution panel or some other wiring device. I was as surprised as you when the electrician I was working for was soldering the stranded conductors together and when I questioned him about it he said it was a mfr requirement. Sure enough, the requirement was there in the instructions.

Originally Posted by Joe Asta

I pulled this off the web. I see this alot since we use ballasts that have push-in terminal blocks. If we use stranded wire, we dip the stripped end in a solder pot so that it can be inserted in the terminal block.

Joe,

Talking two different things here (at least in my mind).

One is the reference above to tinning wires for electronic connection use, and, yes, this also applies to your reference to ballast and lampholder terminals. I used to do that all the time back when I worked in electronics and for tinning wires as that reference says.

The other reference, the one we were talking about, is tinning wires for electrical panels, which is (to me anyway) a completely different concept. In this case, tinning was the coating of copper conductors their entire length.

So ... yes, I will agree with you ... your reference is also "tinning", but ... I will disagree in that it is not applicable to what is being discussed regarding the number of conductors in a terminal in panels.

In fact, as I recall (thinking back more than 40 years here) that tinning for ballasts and lampholders was discontinued when it was realized that the push-in fittings for those lampholders were designed for solid conductors and all the ballast wiring was changed to solid conductors exiting the ballasts, which means it was likely never an "approved" method of 'making do with stranded conductors when solid conductors were needed'. But that is thinking back 40 years ...

Jerry,

I didn't mean tinning the entire length of wire but rather for the termination of stranded conductors (I thought this could be inferred from the context of the discussion but perhaps not).

The equipment in question (where I encountered this requirement) was for an industrial application, not residential if that makes a difference. The only reference I can find so far is to UL508a 29 which mentions the use of soldered stranded conductors as one option for terminating conductors.

I am not aware of a residential panel requiring tinning stranded conductors, so for the context of this discussion I'll concede that there may not be any distribution panel manufacturers with that requirement.

In fact, as I recall (thinking back more than 40 years here) that tinning for ballasts and lampholders was discontinued when it was realized that the push-in fittings for those lampholders were designed for solid conductors and all the ballast wiring was changed to solid conductors exiting the ballasts, which means it was likely never an "approved" method of 'making do with stranded conductors when solid conductors were needed'. But that is thinking back 40 years ...

True today too. The only time I use stranded wire in my designs is when dictated by UL for applications where the lamp wires are movable, such as on an adjustable track light. We have virtually eliminated tinning the wires by using crimped on ferrules. Lessens the chance of accidental burns to production workers.

Listing and labeling!
This is the key.
All electrical equipment must be listed and labeled and must be installed according to the listing and labeling. If it calls for solid wire then you don't tin stranded wire to "make it work". It is a code violation. The code is black and white in most cases. Stranded wire tinned is not solid wire.

Charlie,
To answer your original question one conductor one termination.
Here are 2 nice easy .pdf's to keep in your file for reference. One is the Square D submission to the NEC and one is Square D's info sheet.
Enjoy

Originally Posted by Bob Winchester

Listing and labeling!
This is the key.
All electrical equipment must be listed and labeled and must be installed according to the listing and labeling. If it calls for solid wire then you don't tin stranded wire to "make it work". It is a code violation. The code is black and white in most cases. Stranded wire tinned is not solid wire.

Right, to the point that installations not conforming with listing and labeling are against the code. The control panel I recall working on required solid wire or tinned stranded wire and was labeled for such, therefore since the guy I was working with was using stranded wire (which was listed as acceptable) to make it a "compliant" installation he had to tin the ends of the wire before terminating them. This was nearly 10 yrs ago so it's possible that tinned stranded wire has been abandoned entirely by the industry - I don't know since I no longer do electrical work.

To OP, IMO the nuetral wires are part of the pathway for the current to flow. There fore the wires could warm up. If 2 or more nuetrals are under same set screw, this could warm to the point that the screw may loosen and cause an incomplete or arcing circuit. The wires could become corroded due to the loosening or arcing.
The plain copper wires are for a ground to be used for electrical spikes to the ground only. The current usually will flow in two wires hot and neutral. It is also improper for nuetrals and grounds to be under same set screws. for the above reasons. So Yes I call it out as an improper connection regardless and suggest further eval from an electrician.

Bob: Where do U get two conductors warming up will cause the connection to loosen? If warm connections cause loosening, we're all in big trouble. What about lugs that are rated for multi conductors? I've used them in large parallel installations having one screw in the lug, think their now loose?
The reason for one neutral/termination has already been stated; so that the removal of one neutral does not result in the intermittent disconnection of the other.

The grounding conductor may be necessary for more than just a 'spike', as U put it. Although caring current for a short time under normal circumstances, (to operate the over current device), the conductor will conduct much more current than the over current device's rating according to its particular time envelope.
Relative to a fuse, lets say, a NON and a FPRN, look at their respective time/amperage graph. Breakers also vary per manf etc.
Bob Smit, County EI

Originally Posted by bob smit

Bob: Where do U get two conductors warming up will cause the connection to loosen? If warm connections cause loosening, we're all in big trouble. What about lugs that are rated for multi conductors? I've used them in large parallel installations having one screw in the lug, think their now loose?
The reason for one neutral/termination has already been stated; so that the removal of one neutral does not result in the intermittent disconnection of the other.

The grounding conductor may be necessary for more than just a 'spike', as U put it. Although caring current for a short time under normal circumstances, (to operate the over current device), the conductor will conduct much more current than the over current device's rating according to its particular time envelope.
Relative to a fuse, lets say, a NON and a FPRN, look at their respective time/amperage graph. Breakers also vary per manf etc.
Bob Smit, County EI

An electrical seminar we just had with a code electrician. I guess i will call him and tell him he is full of **** and that all the inspectors at this place know better than he does.

It amazes me to see some of the stuff written here that is not factual. The reason you don't put 2 conductors in a terminal is because the terminal is listed for 1 conductor. UL or the listing agency has done testing and determined 1 conductor is the correct fill for the terminal. We can't guess why this is without getting a report from the testing agency to determine why they determined this to be right. It might be the manufacture didn't ask for a rating for more than one conductor. They test for what is asked for. Some terminals are rated for more than one conductor. They are also rated for conductor sizes and solid or stranded. All of these decisions are made by engineers and it is not our place to ask each other why. Speculation has no part in code enforcement. The most abused term in code enforcement is "interpretation". Think about that statement for a while. That term is every inspector's answer for "vest pocket rules". Am I covering too much here? I do seem to be skipping around a lot. I'll quit now.

There is nothing 'electrically' wrong with having two neutrals under the same screw from a circuit operation point of view, and you are correct in that there would be no difference in that and terminating it on the next screw down the bar (provided more than one wire under a screw is in accordance with the panel manufacturer's instructions). However, bearing in mind that one purpose of the neutral is to provide a reference point for the circuit, the problem that could arise is when you have to work on one of the two circuits. Say, for example, that circuits 1 and 3 have their neutrals under the same screw. You need to work on circuit 1, so you turn that one off and proceed to disconnect the neutral. Since they are under the same screw, the neutral for circuit 3 is now loose also and may well have become disconnected from the neutral bar itself. This condition can result in an overvoltage condition for the still-energized circuit 3, possibly causing damage to that circuit's connected load. Of course, you can argue the unliklihood of there being any resulting problem, but as I understand it, that scenario was the basis of the requiement change some years ago. Hope this helps

It appears to me that there are practicing electricians that do not understand basic electrical circuit theory and think Physics has something to do with an exercise class in high school., Why do you think double taps are forbidden at the breaker connection? Just to sell more breakers?

An electrical seminar we just had with a code electrician. I guess i will call him and tell him he is full of **** and that all the inspectors at this place know better than he does.

There are a lot of misconceptions about the two grounded legs issue under one terminal screw in a load center neutral bar. The heating of the conductor(s) loosening the screw is one of them..... Your electrician giving that seminar will be hard pressed to find documentation supporting that claim. The screw terminations of a load center neutral bar are listed for more than one conductor of the same size.

The proposal by Mr. Pauley of square d (that was accepted by the cmp) in the Pdf file in an earlier post was to coordinate the language of NEC 110.3(B) and UL 67 with the listing and installation instructions of the manufacturers. This was because too many installers were not reading the panel instructions. So in 2002 the new language in 408.41 was added to clarify the requirement on one neutral or grounded leg per termination. Heating of the conductors was never an issue. Mr. Pauley then goes on to explain the dangers of this practice involving mwbc and also the disconnection of the grounding conductor if terminated under the same set screw with a grounded leg. Again heating of the conductors was never an issue.

If heating was an issue for causing loose high resistance connections to multiple grounded conductors under one screw then the many thousands of panels that were not in compliance with the new code language of 2002 NEC 408.41 would be a huge fire hazard that could not be ignored. And likley would have shown its ugly head years before the code (language) change occurred.

Originally Posted by Stuart Brooks

It appears to me that there are practicing electricians that do not understand basic electrical circuit theory and think Physics has something to do with an exercise class in high school., Why do you think double taps are forbidden at the breaker connection? Just to sell more breakers?

Stuart

Are you talking about branch circuit breakers? There are branch breakers like the Square d Homeline and QO that allow two conductors from two separate branch circuits to be terminated to the breaker lug. It all depends on the listing for the breaker . It is not an across the board requirement.

The exception we are talking about is the special language for neutral or grounded leg conductors of branch circuits under a single terminal even though the terminal is listed for more than one conductor . The restriction being that the multiple conductors be egc's.

Good job Robert! I was starting to wonder if anybody out there read the posted PDF's that pretty much explain the issue as stated by the manufacturer. Also, good job on explaining the fact some breakers are allowed to have two conductors.
It appears to have been an accepted wiring practice for doubling up the neutrals in past years but most homes I've seen in the area after 2004 almost all have been done correctly. I think the electrical inspectors and doing a better job now that they understand the proper application.

Originally Posted by Roger Frazee

Stuart

Are you talking about branch circuit breakers? There are branch breakers like the Square d Homeline and QO that allow two conductors from two separate branch circuits to be terminated to the breaker lug. It all depends on the listing for the breaker . It is not an across the board requirement.

Yes - in general. Of course, there are special breakers that allow that. That isn't the issue.

Originally Posted by Roger Fraze

The exception we are talking about is the special language for neutral or grounded leg conductors of branch circuits under a single terminal even though the terminal is listed for more than one conductor . The restriction being that the multiple conductors be egc's.

My question was why are double taps not allowed, and let me clarify this, on a standard branch circuit breaker? Do people think it there is a logical reason for this or perhaps the NEC council wanted to help the manufacturers sell more breakers? The question was, and is still intended to be, rhetorical. There are other comments in the discussion. Look at a few of them and it's pretty clear, whether inspector or a sparky, the poster doesn't understand fundamental electrical circuit theory, alternating current, or the purpose of a grounded conductor or a branch ground.

As for manufacturer's instructions, they aren't always present in the inspection world. I sometimes, do see a panel that has a table listing the number of conductors of a certain guage that may be allowed under a terminal lug but certainly not in all panels. I don't bother to look for one unless there is a reason at the time. In every case I have seen the table, it specifically states for ground wires only, not grounded conductors. I admit, I haven't seen every panel made by every manufacturer for the past 30 years. I will always take the safer side of an ambiguous rule when my clients are concerned.

I certainly can't find argument in some of your post. It would be better to detail why a lug or termination will not except more than one wire or cannot be double tapped so that those you feel do not understand will gain some knowledge in that respect..

MY point was that the ambiguity that existed before the language change in 2002 NEC 408.41 for grounded conductors and neutrals under the same screw in a neutral bar was eliminated. It is now clear that you must terminate only one grounded leg or neutral per terminal. It used to be SOP to terminate a couple grounded legs in a single terminal screw hole. One of the issues that contributed to the reason for this practice was they never gave you enough terminations to land all the grounded legs and egc's if all the breaker positions were used so you doubled up to avoid maxing out the terminal bar before you were finished terminating the branch circuits. Manufacturers now 'brag' about having plenty of terminations available in the literature (sales pitches) about their load centers..... With the advent of split neutral design and grounding and neutral bars made available on both sides of the breaker columns wire management and workmanship issues have been greatly reduced, especially in the 40 to 42 circuit panels.

Interesting new development in that regard ... With the elimination of the 42 circuit rule manufacturers are now coming out with 60 circuit residential load centers .. you can imagine how many branch circuit wires are going to be terminated in those babies... Your going to have to really be on the top of your wire management and workmanship game when installing these panels. Take a look......

http://static.schneider-electric.us/...1100HO0802.pdf

We are beating the dead horse, so I will sum up and a statement for what it's worth.
Only one grounded conductor per termination, code & manf specs.
Reason; so that a neutral doesn't inadvertently lose connection while removing another.
Most panels list the terminations for a number of grounding conductors under a screw provided they are solid and of the same gage. Again, one must read the panel label for specifics.

In answer to the statement that the reasons are not important or not for us to know......AS an AHJ, it is my business to know the reasons for a code requirement in order to know its intent. The more knowledgeable an AHJ, the better he can perform his responsibilities, especially when granting special permission(s). These reasons, I believe, also help HI's in there job.
I agree with the issue of shirt pocket AHJ's, which is illegal in my State of MI.
Bob Smit, County EI

Originally Posted by bob smit

Reason; so that a neutral doesn't inadvertently lose connection while removing another.

Correct, and the same risk does not apply to groundING conductors as applies to groundEd conductors and ungrounded conductors - both of which are intended to carry current, while the groundING conductor is not intended to carry current.

Yes, there is a heating up affect as ALL terminations will heat up, including those with only one conductor in them ... BUT ... the reason is as Bob stated.

Please excuse my violating, my statement above regarding 'beating the dead horse',.... just had to throw this one in:

In those circumstances where I encountered an old 12inch wide panel, such as the GE where there isn't any logical room to mount an additional grounding buss, I would allow the installer to terminate his new circuit with the same grounded & grounding conductor of the same circuit
under a termination.

My reasoning was that the termination screw would not be loosened unless that particular circuit was obviously the one being worked on.
In these panels I'm describing, one cannot even get all the circuit conductors tucked in the side troughs let alone adding an auxiliary buss in there. These panels have the grounding & grounded buss in the bottom of the panel which was the least the manf. could do for us.

This was one of the 'least of the evils' I sometimes talk about.
Open to any other ideas....?
Bob Smit, County EI

Bob,

I had to add a ground bar to an older Square D fused and breakered panel. The main was fuses on a pullout and the rest was breakers like todays panels. I mounted the bar on the bottom. I just had to play with the spacing to get the tapped holes between the factory KO's.

Originally Posted by Gary Burnett

Charlie,
To answer your original question one conductor one termination.
Here are 2 nice easy .pdf's to keep in your file for reference. One is the Square D submission to the NEC and one is Square D's info sheet.
Enjoy

Gary,
Thanks for posting the pdf docs.saved them to a file for future referance. I can now finally quite trying to read the faded labels on electric panels.

Originally Posted by bob smit

Please excuse my violating, my statement above regarding 'beating the dead horse',.... just had to throw this one in:

In those circumstances where I encountered an old 12inch wide panel, such as the GE where there isn't any logical room to mount an additional grounding buss, I would allow the installer to terminate his new circuit with the same grounded & grounding conductor of the same circuit
under a termination.

My reasoning was that the termination screw would not be loosened unless that particular circuit was obviously the one being worked on.
In these panels I'm describing, one cannot even get all the circuit conductors tucked in the side troughs let alone adding an auxiliary buss in there. These panels have the grounding & grounded buss in the bottom of the panel which was the least the manf. could do for us.

This was one of the 'least of the evils' I sometimes talk about.
Open to any other ideas....?
Bob Smit, County EI

I was speaking with a master electrician the other day about a home inspection i had done the day before on this very issue. The panel had double lugged neutrals and as i was looking at the room in the panel the electrecian had no choice but to double up because of the lack of room to add an additioal bar. His solution was to wire nut two of the neutrals together and then run a single wire from the wire nut connection to the terminal.
What say ye

Mark, As a Master and a AHJ, I cannot stress enuf the importance in knowing the intent of code and, only one (1) neutral under a termination.
This is a case in point. Having two (2) neutrals in a wirenut with a pigtail to a termination is no different than the two neutrals running to the termination. Whether loosening the termination screw or the wirenut, both neutrals would be disconnected.

It would be okay, and is sometimes done, to wire nut a few grounding conductors with a 'pigtail' as long as the pigtail was sized per the sum of the grounding conductors. EX: (2) #14 ga grounds, pigtailed to (1) #10

As has been stated; inadvertently disconnecting a grounding conductor momentarily due to more than one grounding conductor in a termination (or a wirenut), does not pose a realistic hazard. Disconnecting a grounded conductor (neutral) does and will cause a hazard especially if it is part of a multi-wire branch circuit.
Bob Smit, County EI

Originally Posted by bob smit

I would allow the installer to terminate his new circuit with the same grounded & grounding conductor of the same circuit
under a termination.

Open to any other ideas....?

Originally Posted by Jim Port

I mounted the bar on the bottom. I just had to play with the spacing to get the tapped holes between the factory KO's.

Others too, I am sure, I know I have, done the same as Jim - I would not allow the groundING conductor to be in the same terminal as the groundED conductor ... years ago before I understood it was wrong, yeah, I did it too.

Originally Posted by mark tyson

His solution was to wire nut two of the neutrals together and then run a single wire from the wire nut connection to the terminal.
What say ye

Originally Posted by bob smit

This is a case in point. Having two (2) neutrals in a wirenut with a pigtail to a termination is no different than the two neutrals running to the termination.

Actually, that is different as the two neutral are now effectively 'one circuit' and doing the wire nut joining there is no different than joining with wire nuts in a junction box - as long as one know WTH they are doing (which mean NOT joining two circuits under one wire nut).

Very few panels have more breakers than places for neutrals, so unless they added in some breakers they are not supposed to have, or have multiple tapped breakers too, there should be enough neutral terminals to go around - and if not - then the electrician needs to get into it in more depth and figure out WTH someone did to create that situation and correct it properly.

It would be okay, and is sometimes done, to wire nut a few grounding conductors with a 'pigtail' as long as the pigtail was sized per the sum of the grounding conductors. EX: (2) #14 ga grounds, pigtailed to (1) #10

That would only be needed if the neutrals were from difference circuits (see comments above) in which case joining them would not be a suitable action (see comments above of correcting that), if the neutrals were of the same circuits (the only acceptable condition to wire nut them together) then 2 #14s could go to 1 #14 to the neutral terminal.

Unless were not understanding each other Jerry, the grounded conductor of one circuit can have no interconnection with another circuit.

I was not trying to describe two (2) cables from the same circuit entering the panel, where the installer would then wirenut the two grounded and ungrounded conductors together with pigtails.
Bob Smit, County EI

Originally Posted by bob smit

Unless were not understanding each other Jerry, the grounded conductor of one circuit can have no interconnection with another circuit.

Which is what I was saying - although apparently not very well.

I was also saying that if there are not enough neutral terminals there is likely a reason, and that reason is likely that there are half-size, tandem, or piggy-back breakers in there which should not be in there as that would create more circuits than intended for that panel, which would then translate to not enough neutral terminals. Otherwise, with the proper breakers, there should be enough neutral terminals - which is why I said the electrician should look deeper than just how to reduce the number of neutrals to match the number of neutral terminals by splicing them with wire nuts.

Did I do better than time?

Originally Posted by Corn Walker

It's really a very simple answer: You can't put two (or more) conductors in the same terminal unless the manufacturer says you can.

Can't help myself - I have to disagree with that statement: "unless the mfr. says you can."

The NEC specifically prohibits installing two grounded conductors under the same terminal - 408.21.

Just because a mfr. says you can do something doesn't make it so; many mfrs. provide installation instructions [out of ignorance] that are in violation of the code.

Just because a mfr. says you can do something doesn't make it so; many mfrs. provide installation instructions [out of ignorance] that are in violation of the code.

Not necessarily true with UL codes. When a product is brought to market, it has to be extensively tested in order to get a listing. This listing includes what is called "Section General". Included in the section are exceptions to the code that have been extensively tested on that particular product to meet the safety requirements of the code.

This allows manufacturers to bring innovations to market that will more than likely become the norm for future standards.

I am not versed in the history of NEC codes but I believe that many of the ammendments to sections in newer versions of the code include statements such as "unless allowed per manufacturer's instructions"

Dana, am so glad somebody else made that statement....'manf..out of ignorance'...... is why I don't let a manufacturer be the authority in an installation at all costs.

A case in point: A certain generator manf instructed in their manual, to install a grounding electrode as required by NEC. Furthermore, the electrician was to connect it with a #12ga wire.
I brought this up at their factory and the engineers were not aware that this was only a separately derived source requirement, which their genset(s) are not!
Their final remark was that it wouldn't hurt (trying to save face).
Subsequently, their manual has changed.

In every installation I inspect of these home gensets, I make them remove the connection to the ground rod they've installed (if so).
The last thing we want is for a large overcurrent running across grade to find this rod and take out the generator when, very likely, they will be needing it just about that time.
The gensets already are connected to the premises grounding sys via a grounding conductor run with the circuit conductors.
Of course there is always a possibility that any overcurrent running back at the genset from the premises electrical sys could do some damage but, hopefully the overcurrent would be dissipated before hand.

I apologize for getting off subject, ... just couldn't help myself.
Bob Smit, County EI

Originally Posted by dana1028

Can't help myself - I have to disagree with that statement: "unless the mfr. says you can."

The NEC specifically prohibits installing two grounded conductors under the same terminal - 408.21.

Just because a mfr. says you can do something doesn't make it so; many mfrs. provide installation instructions [out of ignorance] that are in violation of the code.

You seem to have been arguing against a point I was not making. I did not say that if the manufacturer says you can, then you can. I said that if the manufacturer does not say you can then you can't. (Those two statements are not the same). There may be other reasons that you can't but absent those reasons you STILL need the manufacturer to say you can.

For example, the NEC says you you CAN put two GROUNDING conductors in the same terminal, but you can only do so if the equipment manufacturer lists and labels it for such. Here's a simple truth table for you to understand this:

NEC|Mfr|Allowed
No |No |No
Yes|No |No
No |Yes|No
Yes|Yes|Yes


Make sense?

Originally Posted by Corn Walker

Here's a simple truth table for you to understand this:

NEC|Mfr|Allowed
No |No |No
Yes|No |No
No |Yes|No
Yes|Yes|Yes


Make sense?

Yes, that is just another way of stating that the most restrictive applies.

So, where are we then? It has been my understanding that you cannot mix neutrals and equipment grounds on the same terminal. Only one neutral to a terminal and up to three equipment grounds on a terminal. Does this stand up?

You are where you are because of decisions you have made.

Patrick Belcher
U.S. Inspect

Originally Posted by Patrick Belcher

So, where are we then? It has been my understanding that you cannot mix neutrals and equipment grounds on the same terminal. Only one neutral to a terminal and up to three equipment grounds on a terminal. Does this stand up?

That only partially stands up.

"Only one neutral to a terminal ... " that stands up and is completely correct.

" ... and up to three equipment grounds on a terminal." that only partially stands up and many grounding terminals are only rated for two conductors, not three, and some are only rated for one conductor.