Tighten tug and re-tighten ?

[Red Wiggler]

Austn Texas

Austn Texas

What part of the world are you in?

Austin Texas is the nearest big city, our headquarters are in Manor (pronounced May-nor) just East of Austin. We have small shops in Dallas, Houston, and in the Valley (Down South). We also have a small office in San Antonio.

 

[hardworkingstiff]

FYI, Square D torgue response

FYI, Square D torgue response

Where in the gear torque specs or in the torque wrench instructions does it say:

'Torque, shake, repeat?':-?

I called the Square D rep today and told him I was installing two 4/0 cables in a lug on a 400-amp breaker. I told him I have been in discussions with other electricians on what the proper way to tighten the conductors is. I told him some electricians say torgue it and leave it, and others (including me) torgue it to the spec, wiggle the conductors about an inch to an inch and a half in all directions then torque it again, repeat until the torgue setting holds after the "wiggling".

I asked him what the proper methodology would be for tightening the lug on this breaker (the lug is rated for 2 conductors up to 250 kcmil).

Here is his response:

Lou,
I talked to our breaker application engineer & he said what you are doing is a good practice.
There is nothing in writing in our instructions, but it makes practical sense to retighten
these lugs.
There is more chance for the conductors to " spead out & settle in" when using 2 conductors.

 

[chris kennedy]

Thanks Lou, I'll think about that. To this day I have been a torque-em leave them guy.

 

[chris kennedy]

One more thing. If I wiggle and retorque the parallels, now I have to retorque the mains connections to the buss due to the fact that the shaking has compromised that connecioin also. Sounds like work I don't have time to do.

 

[hardworkingstiff]

One more thing. If I wiggle and retorque the parallels, now I have to retorque the mains connections to the buss due to the fact that the shaking has compromised that connecioin also. Sounds like work I don't have time to do.

Fact? That's a strong word.

The breaker I was using is in an enclosure with line and load conductors. Most of the 400-amp breakers I use are either I-Line or bolted to the buss and shaking the conductors would not loosen that bolted connection. You must be talking about something I've not had experience with.

 

[Natfuelbilll]

Question 2.........
Have you ever used a torque wrench to measure your efforts?

I am not 100% sure that all manufacturers termination provide a spec for tightness, I would bet most do, and where they do is it then a Code violation to NOT use a torque measuring device?

 

[chris kennedy]

and where they do is it then a Code violation to NOT use a torque measuring device?

I doubt you will get a red-tag for not using a torque wrench, but IMO it is implied.

110.14

FPN: Many terminations and equipment are marked with a tightening torque.

Handbook commentary following 110.14.

Section 110.3(B) applies where terminations and equipment are marked with tightening torques.

 

[hardworkingstiff]

I doubt you will get a red-tag for not using a torque wrench, but IMO it is implied.

I agree. It's also the difference between a professional and .......

 

[Natfuelbilll]

I agree. It's also the difference between a professional and .......

For clarification... do you mean a professional will use torque measuring tools for terminations, whereas a ......(unqualified ?) would not?

 

[Mr. Wizard]

Austin Texas is the nearest big city, our headquarters are in Manor (pronounced May-nor) just East of Austin. We have small shops in Dallas, Houston, and in the Valley (Down South). We also have a small office in San Antonio.

I know exactly where Manor is located. I heard that work is booming in Austin, but I heard that two or three months ago. It seems everytime I drive into Austin I see several high-rise cranes west of I-35 , near UTA.