What do you use to terminate small gauge stranded THHN wire on circuit breakers and devices?
I usually use the T&B Sta-Kons or 3M Highland crimp terminals but have also tried those Ideal Terminuts in the past.
Just want to see what method others are using and if maybe there is something different available.

TKX

Devices and breakers are listed to accept stranded 12 and 14ga THHN

Clamps: Nothing.
T&B if I need a good (any) termination on a screw.

I'm so paranoid that even with solid, I wrap the screw. Those pressure connections seem to loosen up as I twist in the device.

K-J!! 16&0 Whata Ya think!!!!

when I am forced to pull stranded to a device and the job doesn't spec the clamp type devices... I'll use some solid when I make up the box.

I've never had to connect smaller than 12 stranded to a breaker (which will work ok).

I found it helps to twist the wire counter clockwise before making the hook with stranded.

In fact, I think I learned that here on ECN from a "tips" thread. Best bit of advice I've ever found here, sure helps with my traffic lights.

Ian A.

Same here. If I must terminate a stranded conductor on a screw terminal, I grab the end of the wire and twist it so tight that it almost handles like a solid conductor.

Simply stripping a stranded conductor and wrapping it messes up the natural lay of the strands and once you tighten the screw down, you end up mashing them down. Strands end up being left out of the termination. I don't like it.

In a perfect world, I'd use T&B Sta-Kons for all stranded to screw-terminal connections but that's another story.

Most of us do not realize that most devices, outlets and switches are NOT rated for stranded wire. Read the listing on the box and you'll be using solid pigtails.

The screw terminals of all UL listed 15 and 20 amp devices are listed for both stranded and solid building wire.

I seems that everyone does pretty much the same thing.
It’s true that device screw terminals are listed for stranded wire as well, but it’s sometimes a pain to wrap the wires neatly without loose strands, especially on the screw terminals of less expensive commercial spec grade and resi grade receptacles.
I will sometimes twist and then loop the stranded wire around the screw terminal as if I were looping to second device and then, after tightening, snip it off about 3/16” beyond the screw so the little piece of remaining insulation holds the strands together neatly.
However, many times in order to make things easier and to follow the UL 508a standard, I, like many other electricians, will use other approved means for terminating stranded wires as well.

UL508a Standard
A connection to a wire-binding screw shall be made as follows such that no loose strands protrude from the connection.
a) Solid wire formed into a loop at least three quarters (270 degrees) around the terminal, or
b) Stranded wire that is:
1) Soldered.
2) Connected to a terminal provided with upturned ends.
3) Connected to a terminal provided with a cup washer, or
4) Connected to a crimped pressure terminal connector or eyelet.

On circuit breakers, I personally don’t like connecting stranded conductors smaller than #10.
I’ve seen too many problems with heating and corrosion between strands with the squashing and separation that occurs with the clamp type terminals, like on SQD QO. The brands like Siemens that have a plain screw terminal seem to be worse by sometimes letting loose strands ride out the side of the screw when tightened.

JMHO

From the UL Guide for Receptacles for Plugs and Attachment Plugs.

Can both of you provide documenatation to your statement?

Don did provide a link to UL, and further info can be found in the UL white book.

I do not happen to have the white book on this computer, but I will try to dig it up later.

My apologies, Don posted between the time I read the posts and when I posted.

The UL whitepages are availble at ul.com go to certification on the left side of the screen or click here

I have always taken the stripper about 2.5 inches from the end of the wire and pushed the insulation off just enough for wrapping the screw. Leave the remaining insulation on. You then can wrap the insulated end back around the recept and the wire never fray's. Connectors are very expensive, especially the good ones. Never been called on it.

As "the kid" stated, twisting the strands counterclockwise prior to termination on device terminal screws will result in the tightening of the screw actually twisting the strands more tightly, as opposed to the untwisting effect that normally would occur.
BTW,

The UL White Book is a valuable investment.

I like the method JValdes mentioned. I never tried twisting it counterclockwise so what great information! Stranded
wire smaller than #8 seems to be a pain to work with. I can't understand why some guys prefer it. I only use it if it is specified or the kid behind the counter gives me the wrong stuff. Can someone list advantages other than flexibility? Just curious.

I don't know that anyone actually prefers it, but think it is it is sometimes better for use in flexible conduits where there is vibration, like at motors, or to take strain off relay terminals.
Sometimes on long conduit runs with tighter bends it can pull easier, but not always.
I do remember reading some theory that stranded wire could carry current more efficiently than solid wire.
It had something to do with eddy currents between the individual strands, but I would have to hunt around on the web to find it again. It may have just been a bunch of balony.

When I terminate stranded around screws, I will go down about 1" and strip it back just enough for the screw. The insulation is not removed from the wire but left of the to prevent the strands from going helter skelter when the screw is tightend down.

I usually use devices that have the pressure plate terminals with stranded wire. If I can't get those, then I crimp spade terminals onto the wires, and put them under the screw heads.

That's what I'll do with the traffic lights if the two-years-older and dumber-than-me guy at the orange box gives me #10 instead of #14. Kinda hard to get the #10 under a terminal block screw w/o taking the screw out and losing it.

Gonna have to try the 'leave the insulation on' trick with the next signal.

Ian A.

I strip the wire back, leaving a short piece of insulation on the end & give it a good twist before terminating around the screw. I run mostly conduit & always pull stranded wire. Stranded wires are always easier to pull than solid. Try pulling 8 or 9 solid 12 ga. wires through a 1/2" conduit with three or four bends.

Dave

Just because it says you CAN pull 9 #12s in 1/2" doesn't mean you should
I might do it for a short straight run but I am not a masochist. That is why they make 3/4"

I do agree stranded is easier to pull.

That is why they make wire lube.

In many instances you don't even have to pull stranded. I always try to push it first, if it looks possible. Only on short runs with minimal bends. When i was doing high rise condos in South Florida, we never used a fish tape in the apartments. Just pushed it all in. I have fond memeroies of those days, yound and eager. Sometimes pretty stupid too.......LOL

The allowance in the UL white book for stranded wire under a binding screw is CRAP!!!


It would be ok, if instructions were included in the instructions for the device, but there isn't any.

Above is opinion, not method of enforcement.

From the UL White Pages, "RTRT Receptacles for Plugs and Attachment Plugs"


Click here For the whole speil

UL498 (Attachment Plugs and Receptacles) seems to refer to both stranded and solid wire for most sections, with the execption of push terminals for field wiring, which are solid only. There is a lot of "shall be wired with solid or stranded" language for the various tests. IMO, this suggests the devices should work with both, but could perhaps be lab tested in only one configuration or the other. See attached UL498 standard for reference

I noticed that some posters mentioned the cost and added labor of crimp terminals as prohibitive.

Just wanted to clarify that 3M and others make very affordable, high quality, non-insulated fork and ring terminals for 12 to 10-gauge wire. These are what I like to use, since there is usually no need for the expensive insulated crimp terminals in this situation. The non-insulated terminals also take up less room and make it easier to set the devices with a box that’s less than 2-1/8" deep.
Stripping and crimping can be done with the same pliers, so I feel that single pigtail installation is as fast or faster than traditional strip, counter twist, form loop, tighten, trim excess, and the connection quality should be more consistent when there are several installers with different skill levels and connection techniques working on the same job.
If you will also be doing future service work at the facility, and need to replace worn devices, I would think that the minimal initial added expense of these terminals will be offset through the savings of time necessary to repeat the above process over again for each connection on every device.

JMHO

I would hate to see or work on the devices with uninsulated terms.

I would rather wrap the stranded.




Only if those pliers are on the list of acceptable tools but the terminal manufacturer.

Well I think that is bull.

I can make great stranded to screw connections. Every one of them is a better connection then Wagos or backstabs.

Hey Bob i will agree with your last statement i done this many time and i am not tooo crazy with the Wagos unless they have one of the build in levers [ but that other story i will deal with that later ]

Merci, Marc

One of my IBM jobs was "service planning". Those are the folks who predict what happens to a product once field techs start working on it. Field crimped terminals are always a concern. That is why we made great efforts to be sure they had the proper tool. A properly crimped terminal is as strong as the wire itself but an improperly "squashed" terminal is a problem waiting to happen. "Twisted and taped" usually performs better.

Taped?