Torque Wrench

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speedypetey

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Hudson Valley, NY
I need to replace my old torque wrench.
What do you recommend? I'm thinking 3/8" but should I get the in/lb version or the ft/lb one? Which will be more versatile for all around use?
 
Re: Torque Wrench

I use the 3/8 inch pound set for most things. Cementex makes an orange insulated set that's darned handy for re-torques of energized equipment. If you're torqueing bigger transformers, switchgear and bussways, you'll also need a foot pound one.
 
Re: Torque Wrench

Here's the set you want. It has everything you will ever need:

57060_ICON.JPG


Master Electrician's Torque Tool Kit
Klein #57060

Two micrometer-adjustable torque wrenches.
Nine hex-wrench bits.
Two 7/16" hex-wrench extensions.
One 7/16" female hex-wrench adaptor (Coupler).
One hex-to-square adapter for wrenches and one adaptor for screwdrivers.
One adjustable torque screwdriver.
Seven screwdriver bits; five slotted, two Phillips.
Hinged metal box.
Additional torque screwdrivers available in screwdriver section.
 
Re: Torque Wrench

I agree that the set Bryan posted is a nice one.

If you do not want to get all of that go with the inch pound tool first as that will cover the majority of electrical terminations.

As mdshunk pointed out the foot pound tools only come into play on the larger equipment.

I would advise against any live torquing, make them schedule a shut down.

The customers convenience is not worth my time in a burn ward. :mad:
 
Re: Torque Wrench

I do have a two good 1/2" ft/lb wrenchs for automotive use, so I'll get a nice in/lb 3/8" for the work van. I can always grab a big one out of the automotive tool storage if I need.
Thanks guys.
 
Re: Torque Wrench

You can convert from in/lbs to ft/lbs by dividing the in/lbs by 12.

You can convert from ft/lbs to in/lbs by multiplying the ft/lbs by 12.

Most torques are in in/lbs now adays. Even on some of the larger breakers. I haven't seen ft/lbs on any new equipment in a while.
 
Re: Torque Wrench

tkb, I know, this is an easy conversion, but the values are quite different between the two.
The in/lb wrench is much more accurate as it has a lower maximum torque, and it is adjustable in in/lb's rather than ft/lb's.
 
Re: Torque Wrench

Originally posted by don_resqcapt19:
md, What and why are you retorqueing?
Don
Click to expand...
It's common PM all across this land. I know that there is some discussion that manufacturer torques are only the initial install torque and any "settling in" or cold flow that may change the torque over time does't matter. Some say that that torque should be maintained throughout the life of the equipment. I'm not smart enough to know who's right.
 
Re: Torque Wrench

I think that most experts agree that mechcanical wire terminations should never be retorqued. It is ok to retorque the connection of the connector to the bus bar and bus bar splices, but not the connection of the conductor itself.
Don
 
Re: Torque Wrench

Don -- is cold-flow of aluminum conductors in mechanical lugs no longer a problem?

I haven't used aluminum much in a long time, and I haven't used mechanical connectors on them in years. (I try to use compression connectors whenever possible on aluminum)

But when I was using them, aluminum cold flow was a problem and caused the connection to loosen up. We were told to retorque them a few months after they were first installed (they were often loose) and then every couple of years as part of PM.

What's the current recommendation?
 
Re: Torque Wrench

Don -- is cold-flow of aluminum conductors in mechanical lugs no longer a problem?
Click to expand...
That is still a problem with the mechanical termination of all conductors, but copper is more forgiving than aluminum. That is why I said:
It is ok to retorque the connection of the connector to the bus bar and bus bar splices, but not the connection of the conductor itself.
Click to expand...
Don
 
Re: Torque Wrench

Don -- it's the mechanical connection to the conductor (wire) itself (if the wire is aluminum) that I am questioning.

Are you saying that the mechanical aluminum wire connection shouldn't be retorqued to compensate for cold-flow?

In the past, I've found a lot of them to be loose. Occasionally, I could literally pull the wire right out of the lug.

I would think that that?is the very connection that should be retorqued.

I'm only talking about aluminum wire connections, not copper -- I've never had problems with copper if it was torqued properly in the first place.

Edited to clarify that I am only talking about aluminum wire connections.

[ July 11, 2005, 02:40 PM: Message edited by: tx2step ]
 
Re: Torque Wrench

The problem is if you keep 're-torquing' you will flatten the wire to a point where it's ability to carry its full rating will be reduced.

Keep re-torquing it enough times and you may cut right through.
 
Re: Torque Wrench

iwire -- I agree. That's why I use copper. And in the rare event that I have to use aluminum I use compression fittings.

But if you have to use a mechanical lug on aluminum wire, or if one is already existing, then what do you do?

Do you ignore it and hope it's OK? Do you check temperature?

Or do you retorque it every couple of years, and after it is deformed enough, cut off the end and start over again with an undamaged end?

I'm just trying to find the best answer, since I don't really know what the best procedure is. What I've done in the past has worked OK, but I don't know if it was the best solution.
 
Re: Torque Wrench

Yes, I am saying that the connection to the wire itself should never be retorqued. If the conductor is properly installed, there is no need to retorque, even with aluminum. If there is any evidence of a connection problem, the wire should be shortened and reterminated. I think that you will find that the conductors that were so loose that you could pull them out of the connector were over torqued on the original installation or retorqued at some point. The specified torque allows for the normal relaxation of the connection.
Don
 
Re: Torque Wrench

OK, here's a curve ball.

Do any of you think or agree that treating the threads has an effect on torque value?
Are the specs given for dry threads?
How do we adjust for coated/lubricated threads?

I know it does as this has a vast difference in automotive engine building. Even the type of lube on the threads requires a different torque spec. Using a high quality moly lube, such as that supplied with ARP brand of fasteners, requires a different spec than let's say regular dino motor oil.

I ask this because I have always coated the threads of aluminum lugs and terminals, such as those found in any meter pan or panel, especially main breaker terminals, with Noalox.
I think we all have seen what can happen to these lugs over time with exposure to any moisture at all.
I have had to go back and work on equipment I did years before and the Noalox was a great help in re-making the connections.

Any thoughts.
 
Re: Torque Wrench

Pete with lubricated threads I would bet you are reaching twice the clamping force with the same torque.
 
Re: Torque Wrench

Originally posted by roger:
Check out, this article on why you should not retorque.

Roger
Click to expand...
Roger -- the article that you referenced is good.

The last part of that article states: " Is it O.K. to check the torque on a connection? Absolutely, but any further action should not be taken until the condition of the connection is evaluated."

My question is -- how do you "check the torque" on a connection without "retorqueing" it?

The only way that I know to check the torque of something is to set a torque wrench to the proper value, then see if it "clicks" without turning the setscrew or nut any further. If the setscrew or nut turns before the torque wrench "clicks", that tells me that the connection was loose or under-torqued.

Roger and/or Don (or anyone else):

I'm not arguing, I just don't understand. :confused:

Will you please explain this so my 3 remaining brain cells will all light up together and say "Ahhhhhhhh"?

By the way, if there is clear evidence of heating, I agree that the connection should be taken apart, damaged parts replaced, damaged wire cut back to good conductor, everything cleaned, oxidation inhibitor reapplied and everything reassembled with proper torque applied.

But I'm still really confused over the issue of how you are supposed to "check the torque" of an existing connection.

Edited to add that I was asking for further clarification from both Roger and Don (and from anyone else). And to fix some poor wording on my part.

[ July 14, 2005, 11:58 PM: Message edited by: tx2step ]
 
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