Torque wrench anyone?

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On larger terminations, all bus, etc...it all gets torqued.

Terminations up to 400A (Wire and lugs) are probably OVER torqued as I don't use a torque wrench on them.
 
All our mechanics have at least two torque wrenches inch LB and foot LB, our diesel mechanics have several one 4' long made by SnapOn, I'd hate to think what I paid for that. But you need the right tool for the job.

I furnished all employees with torque screw drivers, THEY HATED THEM and so did I. One thing it did teach them (I hope) was most mechanics overtighten connections. I believe the torque for the termination connector on a 20 amp outlet was 15-25 inch lbs. Not all that bear down strip the dude tight.
 
Never use one, problably should, everyone laughs when I say "wheres the torque wrench?" We go as tight as possible, without breaking anything of course- havn't broken any gear yet.
 
And John there lies the problem, you can stress bolts that under fault condition can snap ther heads actually they blow off (I have seen this, I was in the room at the time performing an IR scan under load). With aluminim wire you are more likely to damage the conductor strands, though with enough force you can damage the strands of copper conductors also.

All hardware is designed to operate at it's peak performance when torqued to a certain value and as I mentioned most electricians over tighten connections.

Additionally torquing a bad connection does not necessarly improve the connection, a high resistance surface in contact with a high resistance surface torqued propely is not necessarly a better connection, the mating surfaces must be clean and properly prepared.


http://www.vansairforce.org/articles/tips/tip_torque_bolts.html

http://www.mt-online.com/articles/1102_torque.cfm
 
We have set several MCC's. The buss requires a torque of 35lbs I think. It does not feel like much but Square D insist that we torque to that spec. Most of the time with other smaller gear though I am like all the other guys. Tighten it till it feels good.
 
JohnME said:
Never use one, problably should, everyone laughs when I say "wheres the torque wrench?" We go as tight as possible, without breaking anything of course- havn't broken any gear yet.
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dduffee260 said:
We have set several MCC's. The buss requires a torque of 35lbs I think. It does not feel like much but Square D insist that we torque to that spec. Most of the time with other smaller gear though I am like all the other guys. Tighten it till it feels good.
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What would 110.3(A) & (B) say about "We go as tight as possible" or "Tighten it till it feels good"?
 
Thanks for the honest answers. I bring this up because at times it seems to me that an item's listed torque spec maybe incorrect. A few times I've stripped threads before even reaching the recommended specs and there's been times when the recommended torque seemed too light. What to do in these cases? I assume most of us would forgo the specs and tighten the thing until, well, it feels right. Is that wrong?
 
Before blaming the specs - which are pretty much standard - I would first:
- check the calibration of the wrench - they can go out of calibration...sometimes between bolts.
- suspect the material that broke slipped through the QA process..aka, was faulty.
 
celtic said:
What would 110.3(A) & (B) say about "We go as tight as possible" or "Tighten it till it feels good"?
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Ok, here is what we do to remedy this. I will start using a torque screwdriver and torque wrench on all my required connections. When I call for an inspection, I am requesting that the inspector also go behind me and check all the torque settings on the connections that I have torqued.

110.3(A) & (B) wants us to torque all the screws on the breakers, connections, devices, etc. How many people on this board actually own a torque screwdriver and use it on every breaker connection? Out of the several thousand if not tens of thousand breakers I have terminated I have had very few problems. I have had a few, but we live in the real world where time along with safety is of the essence on a project.
 
So duffe what you are saying, is your quality of work is questionable and the inspector needs to check every thing you install, because you have an issue with a requirement?

In practice it is difficult to use a torque screw driver as I pointed out above, torque wrenches are simple to use, and require no more time than a standard wrench and socket or allen.

As more information is available, the NEC sometimes (usally) changes for the better. Determinations were made that torquing connections resulted in a BETTER, SAFER installation.

An advantage of a torque wrench is if anything burns up (high resistance connection) you can stand behind what you did because you properly torqued the connection, per the manufacture requirements, UL Listing and the NEC.

As for breaking bolts, a used bolt that has been stressed, or the wrong spec for a bolt (different grade) will break. In 30 years of using a torque wrench I have only broken a few bolts, and in both instances I either had the wrong spec or the bolt had been previously over torqued (I think).
 
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I got TQ Wrenches for larger gear. I was looking(briefly) for TQ specs on receptacles /switches but could not find them. They weren't on the box.

Tom

I'm sure someone knows where they are!
 
We use them on larger conductors and buss connections. For a time we didn't and had a guy strip the lug on a meter pan late on a Saturday afternoon during a service upgrade. That was the last time we didn't use one.
 
celtic said:
What would 110.3(A) & (B) say about "We go as tight as possible" or "Tighten it till it feels good"?
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Not to mention 110.14. FWIW, the '05 NEC Handbook includes 4 "Commentary Tables" giving torque values for slotted, hex, allen & lug bolts.
 
From a job spec

Tighten all electrical connections to manufactures published torque values. If the valueas are not indicated refer to those published in UL 486A.

I have not checked UL 486A, additionally NETA publishes torque values in there Standards. NEMA has publications as well as ANSI and IEEE.

http://www.zerofast.com/torque.htm

After checking UL486A it says basically this does not apply to terminals on devices below 30 amps.
 
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dduffee260 said:
Ok, here is what we do to remedy this. I will start using a torque screwdriver and torque wrench on all my required connections. When I call for an inspection, I am requesting that the inspector also go behind me and check all the torque settings on the connections that I have torqued.
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Do you think the inspector will appreciate your sarcasm? ;)



dduffee260 said:
110.3(A) & (B) wants us to torque all the screws on the breakers, connections, devices, etc. How many people on this board actually own a torque screwdriver and use it on every breaker connection? Out of the several thousand if not tens of thousand breakers I have terminated I have had very few problems. I have had a few, but we live in the real world where time along with safety is of the essence on a project.
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Who's safety - Just you and your employees or the end user of the equipment you install?
 
brian john said:
So duffe what you are saying, is your quality of work is questionable and the inspector needs to check every thing you install, because you have an issue with a requirement?QUOTE]

John, what is an inspector for? They are there because there is a question about everyone's quality of work.
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