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#172953 12/30/07 09:49 PM
Joined: Nov 2007
Posts: 763
KJay Offline OP
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.


Joined: Jul 2004
Posts: 9,827
Likes: 22
Devices and breakers are listed to accept stranded 12 and 14ga THHN

Greg Fretwell
Joined: Aug 2007
Posts: 853
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!!!!

Joined: May 2007
Posts: 47
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).

Design-Build isn't supposed to mean design *as* you build.
Joined: Apr 2004
Posts: 812
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.

Is there anyone on board who knows how to fly a plane?
Joined: Oct 2006
Posts: 745
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.


"But the guy at Home Depot said it would work."
Joined: Nov 2005
Posts: 31
Junior Member
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.

Joined: Jan 2003
Posts: 4,391
Originally Posted by jdo1942
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.

Bob Badger
Construction & Maintenance Electrician
Joined: Nov 2007
Posts: 763
KJay Offline OP
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.


Joined: Nov 2000
Posts: 2,148
From the UL Guide for Receptacles for Plugs and Attachment Plugs.
Terminals of the wire-binding screw, setscrew, or screw-actuated back wired clamping types are suitable for use with both solid and stranded building wires.

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