# Torque wrenches and torque screwdrivers



## electures (Oct 23, 2008)

How many of you are carrying torque wrenches and screwdrivers? I recently asked this question to class I taught in South Jersey. Not one contractor responded with a "yes". Is this the norm? Please comment.


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## gilbequick (Oct 6, 2007)

I think it's a tool that a guy who does control work is more likely to use on more pressure sensitive pieces (expensive equiptment). I've wanted a torque screwdriver for a long time now, I just have a hard time justifying $200 for something that I'll probably only use on breakers when a regular straight blade does just fine.


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## brian john (Mar 11, 2007)

I have carried them since 1976 and furnish all my employees with them, it is a tough sell to new employees, even with me furnishing the tools. The screw drivers are the real TOUGH sell.


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## gilbequick (Oct 6, 2007)

Brian, what brand and model do you recommend for general use?


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## electures (Oct 23, 2008)

gilbequick said:


> Brian, what brand and model do you recommend for general use?


I use the Klein #57060 set. It comes with a variety of adapters including the screwdriver w/ bits.


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## Adam12 (May 28, 2008)

Ive always used a torque wrench for gear work. Never a torque srewdriver though. On panels just by hand.
Ive used Huskey to Craftsman torque wrenches or whatever the supply house sends out.


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## brian john (Mar 11, 2007)

SnapOn mostly, easy to get and offer many varieties, We have 3/8 drive ft/lb and 1/4" drive inch pounds, electronic and manual. Our diesel mechanic has a SnapOn that is 48" long 3/4" drive (I THINK)


One thing that surprises most people is how little torque is actually required on a 20 amp CB.


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## Adam12 (May 28, 2008)

brian john said:


> SnapOn mostly, easy to get and offer many varieties, We have 3/8 drive ft/lb and 1/4" drive inch pounds, electronic and manual. Our diesel mechanic has a SnapOn that is 48" long 3/4" drive (I THINK)
> 
> 
> One thing that surprises most people is how little torque is actually required on a 20 amp CB.


Theres always a torque rating on just about all fastners.
Many people dont realize that the torque rating canges when a socket extension is added to the mix.


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## Jim Port (Oct 1, 2007)

Torque wrench for service lugs, but no screwdriver.

When I started to use the torque wrench I was surprised to see how much I must have over-torqued some lugs early in my career.


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## dowmace (Jan 16, 2008)

Jim Port said:


> Torque wrench for service lugs, but no screwdriver.
> 
> When I started to use the torque wrench I was surprised to see how much I must have over-torqued some lugs early in my career.


I worked with a JW when I was an apprentice who refused to use a torque wrench saying that it did not tighten to what he felt was the right torque.

Now years later, I'm going back to fix a lot of his over torqued crap!


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## KayJay (Jan 20, 2008)

I’ve had the 3/8” drive MicroTorque wrenches that you turn the handle base to set the torque for many years. One has a range of 0 to 250-inch-pounds and the other has a range of 0 to75 foot-pounds. When I finish using them I always make sure to store them at the zero setting, so the internal springs are relaxed to help maintain accuracy. I use them for both 3/8” and 1/2” drive bits with socket adapters and inline extensions for larger lugs. Using offset extensions like a crow’s foot or adding length to the handle with a cheater bar will affect the torque value, but not concentric inline socket extensions.
Earlier this year, I picked up a nice Wiha TorqueVario-S, 10 to 50 inch-pound adjustable screwdriver kit that is perfect for circuit breaker or contactor terminals and those AlumiConn connectors.


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## dowmace (Jan 16, 2008)

KayJay said:


> I’ve had the 3/8” drive MicroTorque wrenches that you turn the handle base to set the torque for many years. One has a range of 0 to 250-inch-pounds and the other has a range of 0 to75 foot-pounds. When I finish using them I always make sure to store them at the zero setting, so the internal springs are relaxed to help maintain accuracy. I use them for both 3/8” and 1/2” drive bits with socket adapters and inline extensions for larger lugs. Using offset extensions like a crow’s foot or adding length to the handle with a cheater bar will affect the torque value, but not concentric inline socket extensions.
> Earlier this year, I picked up a nice Wiha TorqueVario-S, 10 to 50 inch-pound adjustable screwdriver kit that is perfect for circuit breaker or contactor terminals and those AlumiConn connectors.


An inline extension will effect torque readings, if the wrench was not calibrated with an extension on it. The reason being is as you turn the wrench you will slightly twist the extension and lose some torque. When I was a mechanic we always did 1ft/lb per 1 inch of extension.:thumbsup:


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## KayJay (Jan 20, 2008)

dowmace said:


> An inline extension will effect torque readings, if the wrench was not calibrated with an extension on it. The reason being is as you turn the wrench you will slightly twist the extension and lose some torque. When I was a mechanic we always did 1ft/lb per 1 inch of extension.:thumbsup:


Not according to the manufactures instructions. I was referring to using a 6-inch long socket drive extension.

[From the operating manual]

DRIVE EXTENSIONS:
When using long sockets or concentric extensions, the wrench may be supported at the head with only negligible effects on accuracy.
There are two types of drive extensions. Concentric extensions extend directly along the centerline of the drive and as such do not affect the torque readings. Other extensions and attachments extend to points away from the centerline of the drive and torque applied with them is different from the torque set on the wrench. Use the following formulas to calculate the correct torque….


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## dowmace (Jan 16, 2008)

KayJay said:


> Not according to the manufactures instructions. I was referring to using a 6-inch long socket drive extension.
> 
> [From the operating manual]
> 
> ...


I realize that they say it is negligible but I know I can torque something with an extension take the extension off and torque it again and it was not torqued as tight as it should have been, it's not a lot but when we're talking in in/lb's here a one ft/lb can be a lot


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## electures (Oct 23, 2008)

I think a lot of contractors and inspectors fail to realize that every termination has a torque specification. Failure to torgue all terminations is clearly in violation of *NEC 110.3(B) Installation and Use. Which states that "Listed and labeled equipment shall installed and used in accordance with any instructions included in the listing and labeling." *A typical receptacle outlet may have a torgue spec of 12-14 inch pounds for the terminals. Utilizing a torque screwdriver may appear to be overkill. However, if that same receptacle supplies life sustaining equipment connected to the critical care branch in a health care facility, the importance of properly terminating the device takes on a whole new meaning. Contractors and inspectors need to understand that overtightening is just as dangerous as undertightening. If the receptacle outlet mentioned earlier fails as a result of improper terminations resulting in the death of a patient, can you spell "liability". 

As NJ licensed electrical inspector, I now require a signed and sealed letter from the electrical contractor certifying that all equipment and terminations have been installed and torqued to manufacturers specifications. This "Torgue letter" is then filed with the permit application and inspection reports, and becomes part of the permanent record of the building.


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## jfwfmt (Jul 5, 2008)

*yep*

I carry a 3/8" drive Craftsman torque wrench on the truck and use it on large conductor terminations (#2 & above). I own a Wiha torque screwdriver but I've taken to not carrying (soo expensive).

/s/ Jim WIlliams

Our Inspectors always seem to turn up with torque wrenches, I guess since we only have service entrances inspected and the POCO may require them to certify the torque.


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## chefsparky (Mar 22, 2008)

So what is the danger for over torque? I build a lot of switch gear and was thinking about buying a torque wrench soon. Is there one that is better then the other?


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## jfwfmt (Jul 5, 2008)

*You can break things*

I had my son calculate the inch pounds to foot pounds conversion, he blew it, I didn't check him and I broke the 200A MLO lug in half.

My buddy overtightened a lug on a 200A 3ph 480/277 meter socket lug and broke it. We didn't spot it, we got to drive 16 miles for a new socket, and the county got to pay for a reinspection.

/s/ Jim WIlliams


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## itsunclebill (Jan 16, 2007)

_As NJ licensed electrical inspector, I now require a signed and sealed letter from the electrical contractor certifying that all equipment and terminations have been installed and torqued to manufacturers specifications._

So I guess the followup question is do you require a cert the wire nuts are tight enough?

I've always been under the impression that it was up to the inspector to show an installation didn't meet code - probably in this case by following up and randomly checking torque against specs on a few things, before accepting or rejecting. Finding something not torqued to spec would flunk the job and re-inspection would not necessarily be checking the same connector, would it?

Requiring a torque cert from the contractor caries no more weight than, say, asking for a cert that the conduit was completely assembled before the wire was pulled. Why, because the contractor has no control over what happens to any connection in the building after he leaves. Repair and maintenance will insure that some of these connections are remade at some point and likely not to spec. Of what value is the cert then? 

I've carried a torque screwdriver and wrench for years and use them religiously where a torque is spec'd. Most guys don't and wouldn't unless pressed.


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## electures (Oct 23, 2008)

itsunclebill said:


> _As NJ licensed electrical inspector, I now require a signed and sealed letter from the electrical contractor certifying that all equipment and terminations have been installed and torqued to manufacturers specifications._
> 
> So I guess the followup question is do you require a cert the wire nuts are tight enough?


Wire nuts do not have torque specs. They would fall under 110.12.


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## itsunclebill (Jan 16, 2007)

If you're dense enough to miss the point, OK. 

A cert could still be required that state the wire nuts were installed tight enough, and would make about as much sense.

Frankly, if I flunked an inspection because of a non code required cert like this we would be in court before we got done.


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## MechanicalDVR (Dec 29, 2007)

Our company supplies torque wrenches and screwdrivers and we get encouraged to make sure we use them.


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## JohnJ0906 (Jan 22, 2007)

I have both a torque wrench and screwdriver.


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## brian john (Mar 11, 2007)

chefsparky said:


> So what is the danger for over torque? I build a lot of switch gear and was thinking about buying a torque wrench soon. Is there one that is better then the other?


 
Several issues.

1. Over torqued bolts are stressed with a downstream fault the bolts are exposed to incredible stresses which can snap the bolt resulting is additional faults.
2. Over torquing connections can drive the Allen set into the conductors and damage the threads.
3. Over torqued Allen's can strip the connector and make any removal of the conductors difficult if not impossible.

Retorquing is not recommended at the original torque value, and any electrical inspector carrying a torque wrench is a bit worthless, because it can only prove the hardware is loose not over torqued.


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## Podagrower (Mar 16, 2008)

For those who do carry a torque wrench and/or screwdriver, when was the last time it was calibrated (I'm guilty here, last calibration was at the factory)


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## 480sparky (Sep 20, 2007)

I'll fess up. I carry both a 3/8" and 1/2" torque wrench on the truck. Complete set of home-made sockets. Calibrated every other year.


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## KayJay (Jan 20, 2008)

dowmace said:


> I realize that they say it is negligible but I know I can torque something with an extension take the extension off and torque it again and it was not torqued as tight as it should have been, it's not a lot but when we're talking in in/lb's here a one ft/lb can be a lot


If you use and support the wrench properly, there shouldn’t be an issue. Why even use an extension if it's not needed. Call me a conformist, but I think I will continue to stick with industry based standards and practices here, as well as follow the manufactures instructions and recommendations, as I have for the last few decades. 
I’m not sure why you would compensate for negligible effect, as this means that it is so small, it is insignificant and not worthy of notation, but if you are comfortable with applying your own formulas in the field to overcompensate for negligible effect, then I say that’s all fine and dandy. 
The only thing is, that if you were trying to set fastener torque within a critical specified minimum/maximum tolerance range, you may not even be close to accurate. 

If you’re using an in/lbs setting with a standard six-inch long socket extension and you’re adding one ft/lb per inch of extension, then that could result in a torque error of approximately 72 in/lbs. Approximate because you don’t know exactly how much you have altered accuracy with your formula and technique. I think this would be defeating precision.

If you were adding one in/lb for every inch, that could result in a torque error of approximately 6 in/lbs.

Using a ft/lbs setting and adding one ft/lb per inch could result in a torque error of approximately 6 ft/lbs, etc...
I should also note, that this would be in addition to the factory plus/minus error tolerance of the torque wrench when properly calibrated.


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