Question about tightening connections to breakers

[Eric29]

I’ve always made wire connections to circuit breakers pretty tight. I recently acquired a screwdriver with torque settings for some other things I was working on, and I decided to try following the recommendations stamped on the side of a Square D 20 amp breaker. 12 gauge wire should be tightened 36 inch pounds the instructions on the breaker said. As I was tightening the connection, it really seemed excessively tight. I thought Iwas going to break the plastic. So I just tightened it by hand and decided to do an experiment.

I took out my digital snap on inch pound torque wrench and fitted it with an appropriate connector. I then took a spare breaker with a 12 gauge wire and tightened it to 36 inch pounds. Nothing snapped, but this is what the wire looked like when I took it out.

I’m not sure that I have a question here, although if anyone has any comments, I would appreciate them. I’m surprised that there would be a recommendation to make a connection so tight.

 

[rlitman]

The terminal must be tightened enough to deform the wire a bit. That impression seems both a bit sharp and deep, but is probably still ok.

 

[tyme2par4]

That looks right to me. On solid wire you should expect some deformation of the conductor.

 

[wyliesdiesels]

Doesnt look that bad to me.

Thats about what i get when i torque lugs.

 

[Eric29]

Thanks folks. I was worried about that deep nick. But if you folks think it looks OK, I appreciate the advice.

 

[ishiboo]

I bought a Wiha TorqueVario when I had to install a BUNCH of breakers/receptacles/etc. for shits and grins. I had a similar experience - rated PROPER tightening torque is much more than I had been using and surprisingly tight! In all the receptacles/breakers/etc. I've never had an issue... but now I will grab the torque screwdriver if I have it handy when installing stuff. It takes ZERO more effort to do it correctly.

 

[ishiboo]

Not sure what brand of breakers you are using as well, but make sure the wire is next to the screw. Square D breakers have a little "pushed down" area on the far sides of the terminal pad which might make a groove like that. But a proper connection does not touch that.

Either way, I don't think it's an issue... and torqued to spec is torqued to spec... believe them over you.

 

[Eric29]

It’s for an HOM panel. I think the wire was pushed too far in when I tightened it. That’s why that nick is there. I’ll try again not pushing it in all the way. It probably will just deform as people said that it should not get a big nick in it.

Edit: When I don’t push it in all the way, I don’t get that awful crease in the wire.

Not sure what brand of breakers you are using as well, but make sure the wire is next to the screw. Square D breakers have a little "pushed down" area on the far sides of the terminal pad which might make a groove like that. But a proper connection does not touch that.

Either way, I don't think it's an issue... and torqued to spec is torqued to spec... believe them over you.

 

[ishiboo]

You can't really push it too far in with HOM/QO... the back is where the wire is supposed to be pushed to.

 

[Eric29]

Thanks. I agree with what you said though. I’ll believe the specs over my guesses.