Thread: twisting of wires in screw terminals and twisting of SE cable outer conductor

I couldn't find the thread where this was posted and where I called to find out why twisting of the outer conductor on SE cable is allowed when twisting of two conductors into a screw terminal is not, but here is the answer.

Twisting two (for this example) #12 bare equipment grounds together to be inserted into a ground/neutral bar which is rated for 2 - #12 conductors in each terminal is not allowed because that gets back to the way they were tested, listed and labeled.

They were tested with the two separate conductors inserted into the terminal, not twisted together, thus there is no rating on the terminal for two twisted conductors, which makes the panel not being used in accordance with its listing and labeling, which is a violation of NEC 110.3(B).
- 110.3 Examination, Identification, Installation, and Use of Equipment.
- - (B) Installation and Use. Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.

Okay, so (the question was) 'Why is it that the outer conductor on SE cable *IS* allowed to be twisted and inserted into one terminal?' (wording to that effect - not a direct quote, I could not find that question).

Answer: Because, as the question states, the "outer conductor on SE cable" is just that ... *one* conductor ... one stranded conductor.

Whether that serves as the groundING conductor and/or the groundED conductor, when that is inserted in *one* terminal, which is rated for *one* groundED conductor or possibly even two groundING conductors, all you are terminating into the *one* terminal is ... *one* conductor. One stranded conductor which was field twisted.

That was an excellent question, I think Jim Port may have asked it, and I did not have the answer - had no idea why that would be allowed, but now I do.

Think of it as a stranded #12 AWG copper ... you do not have to separate the strands to terminate them into separate terminals, so why would you have to "separate the strands" of the outer single conductor on SE cable to terminate it? That is one of the ways it was presented to me.

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I fully understand the issue of listing and labeling for specific configurations, and why things are wrong if not L&L for that installation. This is NOT to be taken as an endorsement of twisted grounds. However, it seems to me that there would not truly be a functional problem with a pair of twisted ground wires IF they are properly tightened under the terminal screw. In fact, it would seem to me that one could make an argument that the practice would actually reduce potential problems from a loose connection on one wire in a two-wire-rated terminal if they were both, in effect, bonded together along a foot or two of their length and only one made good contact with the terminal. In that case, the twisting would bond the "looser" wire and still allow it to function. Right? Or am I missing something?

In practice, from my own long time ago experience trying it, the answer is no, it makes for poor connections and one wire can easily come loose.

With loosely twisted wires done by hand, I could see that. But what I have seen here in the few times that I have come across it -- likely from the same electrician -- is that the wires were obviously chucked in a drill and twisted that way. The result is a very tightly twisted pair of wires.

Originally Posted by Kevin Barre

With loosely twisted wires done by hand, I could see that.

That's the way I did it, by hand using my Kleins

But what I have seen here in the few times that I have come across it -- likely from the same electrician -- is that the wires were obviously chucked in a drill and twisted that way. The result is a very tightly twisted pair of wires.

That probably damaged and fatigued the conductor, that would be a big no-no.

Not to mention that it is so much extra work for nothing when all that was required was to put both in the same terminal, presuming the terminal was rated for two conductors, and, if not rated for two conductors, then twisting two conductors, no matter how tightly, does not make them 'one conductor', so it would not be allowed anyway.

So just to refresh, your issue seems to be the twisting of the conductor, not multiple conductors under the screw terminal.

I am not saying that the stranded neutral is not one conductor. The way I am interpreting the issue above, how would you guarantee that the proper twisting procedure was followed? What is the proper rate of twist? Should the twist be clockwise or counter-clockwise? What if you twisted the conductors counter-clockwise and the testing was done clockwise? Do we now have a L&L violation? That seemed to be your main premise for why this is not allowed in previous discussions as it was not tested that way. Where is this found in the listing of the SE cable? Since you don't get these instructions when the cable is purchased how would you know? Since the twisting is not included in the Code doesn't that make this unenforceable?

Originally Posted by Jim Port

So just to refresh, your issue seems to be the twisting of the conductor, not multiple conductors under the screw terminal.

The issue is "proper termination of the conductor(s)".

You could take *one* conductor, bend the conductor back into a 'U' (or even back and twist it around itself making an eyelet) and then inserting that 'U' (or eyelet) into the terminal and it too would be incorrect.

The *additional* problem with twisting two or more conductors together and terminating them under a screw pressure terminal (worse yet under a screw head) can lead to several "bad things happening", which include, but are not limited to: one or more conductors coming loose; one or more conductors crushing one or more other conductors; one or more conductors being cut in two by one or more other conductors; one or more conductors being cut in two by the terminal screw end; one or more conductors squashed flat by one or more other conductors; etc.

I am not saying that the stranded neutral is not one conductor. The way I am interpreting the issue above, how would you guarantee that the proper twisting procedure was followed? What is the proper rate of twist? Should the twist be clockwise or counter-clockwise? What if you twisted the conductors counter-clockwise and the testing was done clockwise? Do we now have a L&L violation?

Those are some of the questions I also presented, however, in dealing with the outer conductor around SE cable, that is "one conductor".

That seemed to be your main premise for why this is not allowed in previous discussions as it was not tested that way.

No, if you go back an read my posts on it, my main premise is that it is way too easy to create a very poor connection, including loose conductors, and the supporting documentation is that it is not allowed. That 'not being allowed' was the supporting documentation, not the 'main premise'.

Where is this found in the listing of the SE cable? Since you don't get these instructions when the cable is purchased how would you know?

Beats the heck out of me. See, you are basing that on the listing and labeling being my "main premise" and it was not, it was only "supporting documentation".

Since the twisting is not included in the Code doesn't that make this unenforceable?

Twisting of the SE cable single outer conductor is a termination for a single conductor. Single conductors are addressed in that terminals for termination of "more than one" conductor must be so identified. If the termination is not so identified for more than one conductor, then that termination may be used to terminate "one conductor", in this case the outer conductor from SE cable, and, the only way to terminate that "one conductor" into "one terminal" is to ... make that "stranded conductor" into a "stranded conductor" so it fits into that one terminal.

If you want more information than that, you will need to ask Roland or Fred, and if they cannot answer your question you will need to ask UL, or even call one of the cable manufacturers and see if they have "termination instructions" for terminating that stranded conductor.

Please post the information you find out back here. Inquiring minds want to know. Thanks.

Originally Posted by Jerry Peck

The issue is "proper termination of the conductor(s)".

You could take *one* conductor, bend the conductor back into a 'U' (or even back and twist it around itself making an eyelet) and then inserting that 'U' (or eyelet) into the terminal and it too would be incorrect.

The *additional* problem with twisting two or more conductors together and terminating them under a screw pressure terminal (worse yet under a screw head) can lead to several "bad things happening", which include, but are not limited to: one or more conductors coming loose; one or more conductors crushing one or more other conductors; one or more conductors being cut in two by one or more other conductors; one or more conductors being cut in two by the terminal screw end; one or more conductors squashed flat by one or more other conductors; etc.

Come on Jerry,

Have you seen a buss bar? Look at the relationship between the screw surface and the hole. This is not one 1/8" screw surface in a 1/4" hole. The screw pretty much fills the hole assuring good contact with the conductors and the buss. Where do you see all this slop to allow conductors to come loose?

Conductors cut in two when using proper torque values, not a chance. Conductors crushed by other conductors. Then why are multiples, sometimes 3 allowed in any configuration? Are you saying ULs tested method is flawed?

I have seen conductors severely deformed, probably from improper torque values. But even a properly torqued lug will deform the conductor.

If the twisting is such an issue why are the torque values the same on the neutral lug where you have an irregular density of strands vs the hot lugs and their uniform configuration? Should they not be different to assure proper pressure on the strands?

The problems you propose would not happen given proper torquing.

Originally Posted by Jim Port

Come on Jerry,

Come on Jim ...

What, you have a problem with a question being answered?

Where do you see all this slop to allow conductors to come loose?

Jim, Jim, Jim, you need to go back and re-read the posts related to this. I stated that I have personally seen it (twisted wires) in terminals where one conductor comes loose.

How? Because one conductor can wrap around around the other conductor (guess what - that means using a larger termination hole , jeez are you so intent in trying to prove me wrong that you are not thinking and not paying attention?), and, when using THAT LARGER termination hole, the screw CAN bind against one conductor, which is wrapped around the other conductor, which can then bind in the terminal, NOT making pressure contact with the now-loose conductor.

Conductors cut in two when using proper torque values, not a chance.

When, as we have always asked here, is the last time you have seen an electrician use a torque screwdriver or wrench? Heck, when was the FIRST time?

Conductors crushed by other conductors. Then why are multiples, sometimes 3 allowed in any configuration? Are you saying ULs tested method is flawed?

Jim, when are you going to start thinking and reading?

When you place two or three (when allowed) conductor straight into the terminal, the pressure of one conductor is applied on the parallel surfaces between the conductor.

When the conductors are TWISTED, there is the potential for the screw to place its pressure against the higher conductor in the twist, and that conductor CROSSES the other conductor(s) such that the pressure is no longer on parallel surfaces.

I have seen conductors severely deformed, probably from improper torque values. But even a properly torqued lug will deform the conductor.

Finally you are beginning to make sense ... yes, severely deformed (crushed) conductors can be from several causes, improper torque is probably the largest contributor to crushed (deformed) conductors, and twisting them one around the other is another contributor.

If the twisting is such an issue why are the torque values the same on the neutral lug where you have an irregular density of strands vs the hot lugs and their uniform configuration? Should they not be different to assure proper pressure on the strands?

Nope, because the torque is a measure of the pressure applied, and that pressure will be the same.

The problems you propose would not happen given proper torquing.

Not when twisting is not done, correct. When twisting is done, there is the distinct potential for that to happen.

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I got a chuckle out of this panel this AM. Mind you, it's a 1982 installation in a foreign country.

Gould ITE had a different twist on the twisting controversy.

Testing? Which testing lab(s)? Please provide a link to the testing results....

Originally Posted by Rollie Meyers

Testing? Which testing lab(s)? Please provide a link to the testing results....

Rollie are you asking me to prove it is right? I'm just posting the pics.

If an electrician did a major reno in this panel today, would he poke the wires in straight or twist them?

john,
while we are all anxiously waiting for jerry's reply i'll tackle your question. a real electrician would use one wire per hole if he had the extra holes. it makes it easier to trace or move wires down the road. a real electrician would have put the red wire on the top of the screw so it tightens as does the screw. how long is the intermission anyway? do i have time to make popcorn and grab a beer?

Originally Posted by John Kogel

Rollie are you asking me to prove it is right? I'm just posting the pics.

If an electrician did a major reno in this panel today, would he poke the wires in straight or twist them?

I should have been more clear, my query is to Jerry Peck & his "testing".

Originally Posted by John Kogel

I got a chuckle out of this panel this AM. Mind you, it's a 1982 installation in a foreign country.

Gould ITE had a different twist on the twisting controversy.

Thank you for posting the pictures.

Originally Posted by brian schmitt

while we are all anxiously waiting for jerry's reply

Okay, finally got an e-mail back today, I've been passed around from person to person, and this is how the e-mail starts out ...

"Mr. Peck,

Regarding the shielded cable termination, I cannot answer your question without knowing specifically what type designation is marked on the cable, and whether these cables are actually permitted in electrical panels. Once I have that information, I may be able to locate applicable instructions for terminating that cable. Also, are the cables UL Listed?"

The rest of the e-mail is no more helpful.

Guess I'll need to go to the Big Box store near me and take a photo of SE cable markings and the other information he is asking about for the other question about twisting conductors.

By the way, he included this about pre-twisting for wire nuts, and that it 'may be required', 'may not be required', and 'may not be allowed' - depends on the wire nut.

"For your second question on twisting of conductors before terminating, for field-installed applications, this is strictly covered in the manufacturer's installation instructions on the unit container or information sheet within the unit container. For wire nuts, the majority of these will indicate pretwisting is unnecessary, which leaves open the possibility that they may or may not be pretwisted. The instructions may also instruct users to align the ends of the conductors before applying the connector onto the ends, thereby implying no pretwisting. Having said that, however, there are instructions for some twist-on connectors that do recommend pretwisting. This is unusual."

So, I continue on with my search for the answer to that question.

Just wanted to update those still watching and letting you know that you will miss nothing if you get up and go out to the snack bar for popcorn, drinks, and candy bars, which have been discounted for this feature.