I have noticed that it seems to be common practice in my area to strip stranded wire and leave the insulation on the end of the wire to hold the strands together and then wrap this around a termination screw on a recepticle or a switch. I am sure that I saw a comment and illustration in an old Handbook I had that illustrated this as being a wrong practice, but have looked since and cannot seem to locate this information. In my understanding, stranded should only be terminated using crimp ons or on a termination screw with a cup or where the device has pressure plates. Could anyone help on this?

Gunther I will post it later but the UL white book lists all device terms for stranded or solid.

Not to say using crimps is a bad idea.

Bob

From the UL Guide Information for receptacles (guide RTRT).


[This message has been edited by resqcapt19 (edited 09-20-2003).]

Thanks Don, I did not have time to post that this morning.

Bob

Gunther, Dons the one the filled me in on the same question.

While the terminals themselves are listed for solid or stranded wire, what are your thoughts on the specific technique described by gunther? Would you consider this good or bad workmanship?

Specifically: taking the stranded wire, stripping it so that a sufficient length of conductor is exposed, but _leaving_ a length of insulation on the end of the wire, and then wrapping this around the screw terminal. This would keep the strands from coming apart, but would leave and extra dangling bit of wire if the insulation were to fall off.

The technique that I like to use is to strip stranded wire, leaving a bit of insulation on, then using this insulated section to grab and twist the stranded wire tightly, and then to cut this insulated section off. I twist the wire in the 'reverse' direction so that it doesn't 'birds-nest' when I tighten it under the screw. I've sometimes thought about leaving a length of insulation on the wire after the screw terminal, however.

-Jon

winnie:

Some say it is a common practice in their area and some say the short piece keep the strands intact, but I agree with you!



I never did, nor was I ever taught to terminate the conductors as suggested.

I doubt that there are any recognized trade publications that would show that method to those who are learning about the installation practices by electricians.

I could be wrong and if so I would like to see the pages whaer they show this method as being acceptable.

I still believe that the best way to terminate stranded wire on receptacles and switches is to twist the strands counterclockwise prior to terminating.
This ensures that tightening the screw will further twist the wires during tightening, as opposed to the untwisting that would occur if the wires were left twisted clockwise.

Try it sometime!

I will.

Redsy,

I have tried the counterclockwise twist after I saw your suggestion here.

Makes attaching new plugs and sockets when rewiring table & floor lamps much easier!!!!

Looks neater too.
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Gunther, by your argument, then lampholders for table lamps and most regular household Nema 1-15 plugs and connectors must only be wired with solid wire.

The screws on these things sure don't have any pressure plates or "cups". And sometimes I think screws are too small to do the job properly....and in a lot of cases there is no space for crimp-on terminals. You have no choice but to wrap the wire directly around the terminal screw.

[This message has been edited by SvenNYC (edited 09-26-2003).]

Thanks everyone for your thought-provoking replies and insights. I especially like the suggestion of cutting off the tailing end of insulation after tightening the terminal screw. Its great to have a place to share experience so that perhaps the quality and craftsmanship of the trade can be improved. Just for clarification, I am not trying to advance argument, just trying to learn. Thanks.

Another trick that helps when terminating str to receps is to use a pair of needlenose to hold (squeeze) the wire tight around the terminal binding screw while tightening the screw. It helps keep the conductor from blowing out all over the place.

Massachusetts change. 110.14 (A)
"Connection by means of wire binding screws or studs and nuts having upturned lugs or equivalent shall be permitted for 10 AWG or smaller solid conductors. Where stranded conductors are terminated on and not looped through such terminals, the terminals shall be identified for such use, or the strands at the terminals shall be made solid." My question. Are the terminals on receptacles considered wire binding screws? If so according to the ul they are suitable for stranded wire and this article does not apply. I find it easier to crimp on a terminal anyway.

Scott I put up that MA amendment up before, that is when Don showed me the UL listing.

I have not had a chance to talk to a MA inspector about this yet.

It seems that the amendment is meaningless.

I do not use crimps as 99% of our work uses spec grade outlets with back wire pressure plate terminals.

Gunther wrote:


I used the word "argument" to mean statement or position, not "starting a fight" type argument.

Sorry for any misunderstanding.