? for torque screwdriver users

[mark32]

Have you ever questioned manufacturer torque specs? Most of the time the specs seem to feel "Right", other times the specs seems too little or too much. I've stripped out a couple of switches in the past well before arriving at the specified torque. Other times the torque doesn't seem to be enough to hold the conductor well enough in it's terminal. Today I terminated a #12 copper to a ground bar in a Siemens panel. The labeling said to torque to 20 in lbs., which I did but didn't like it so I went up to 22 in lbs and then removed the conductor to look at it and it looked great, two little dimples. I cut it off and torqued it to 22 and then another little smidgen with my regular screwdriver because, again, it felt right. 20 in lbs feels fine on #14 but not #12. The breaker (Siemens) has the same type of terminal setup as their ground bars but recommends 25 in lbs, what's up with that?

 

[jbelectric777]

Actual studies by manufacturing companies along with UL did tests on this subject and found "hot spots" when over tightened.... Learned that in a seminar because I felt the same way.

 

[gary]

Those numbers sound good to me, 20 in lbs for buss bars & 25 in lbs for breakers, a little more for larger sized conductors. These aren't manufacturer "suggestions", they are specifications which must be followed to properly install their devices. The whole point of using torque measuring devices is to remove the subjectivity of having to rely on thousands of different installers knowing how tight it should "feel." That perception for any one installer will also change with the size & shape of the handle on the tool he is using. Unless you suspect an error or misprint in the specification you should learn to trust your torque driver. (Unless you bought it at Harbor Freight, dropped it off a scaffold, or have some other reason to doubt its accuracy.) Also make sure you're not confusing ft lbs for in lbs and know how to convert between the two.

 

[zog]

Any torque device should be calibrated annually.

 

[mark32]

Thanks guys for the replies,

Gary, I agree with your statement about removing subjectivity and how each installer's "Feel" will be different along with one tool may give a different perception of torque than another which is why I bought the tool (Klein) in the first place. I will however assume you were joking with that last statement.

Zog, yes I should send this in to get calibrated, I'll check into that; although I can predict my buddies laughing their ass off when I tell them "I just got my screwdriver calibrated". They already laugh when they see me pull it out of my tool bag, they wouldn't think of using such a tool.

 

[Split Bolt]

Mark, I'll have to admit that I'm one of the old school guys that would have made fun of you! I have a 1/2" drive torque wrench on the van, but always relied on what feels right with a screwdriver. Checked out the Klein website and will own and use one soon! Thanks! Is this the one you have?

http://www.service.kleintools.com/T... SCREWDRIV-SPECDRIVER-TORQUESET/Product/57034

If so, approx. how much does it cost?

 

[Riograndeelectric]

what would you recommend for buying one?

 

[mark32]

Mark, I'll have to admit that I'm one of the old school guys that would have made fun of you! I have a 1/2" drive torque wrench on the van, but always relied on what feels right with a screwdriver. Checked out the Klein website and will own and use one soon! Thanks! Is this the one you have?

http://www.service.kleintools.com/T... SCREWDRIV-SPECDRIVER-TORQUESET/Product/57034

If so, approx. how much does it cost?

Hi there, indeed that is the one I own. I bought it for $130 around 10 years ago at least and that was without the attachments, but it accepts standard 1/4" items which is what I purchased separately. If I were in the market for one I'd keep an eye on Ebay, I now buy most of my tools on there.

 

[zog]

Zog, yes I should send this in to get calibrated, I'll check into that; although I can predict my buddies laughing their ass off when I tell them "I just got my screwdriver calibrated". They already laugh when they see me pull it out of my tool bag, they wouldn't think of using such a tool.

Let them laugh all they want.

 

[mivey]

I have a note somewhere about the difference between targeted torque and the actual torque applied by "feel" but I don't remember how far off the values were.

While all connections probably have some torque spec, I tend to weigh the value of torquing against the relative value of the equipment/process/etc (and terminal type). It does not make it right, but it is the way it is.

 

[jmellc]

I've never even seen a torque screwdriver. I knew they existed. I have used torque wrenches on switchgear or bus duct installs. Somehow, I've never felt the need to torque breakers and neutral bars. Yes, that's bad, I'm not the professional I should be. I've never known anyone else to do it either. None of our supply houses around here have torque screwdrivers on the shelf, so I'm sure no one around here buys them much. I've never had a problem with my terminations, so I spend no time worrying about it.

 

[LarryFine]

I have a note somewhere about the difference between targeted torque and the actual torque applied by "feel" but I don't remember how far off the values were.

If I were to venture a guess, I'd say I tighten over spec far more often than under.

 

[mark32]

In reference to the (Un)popularity of such a tool, aside from being forced to use one (Job spec), I think it mainly depends on the type of individual you are. I like taking the guess work out of situations in my life, whether that is doing electrical work or cooking or whatever. To me, a torque spec is concrete, set it and forget it, I don't have to worry about it later on when I hit the sheets. I tend to worry about stuff that can impact others so if I do it by the book I have less to think/worry about which also saves time and stress, plus I like to do things the right way. No one can fault you down the road for that.

Zog, do you know of a place I can send this to be calibrated? Do I send it back to Klein?

 

[zog]

We use ETI for all our calibrations http://www.electricaltestinstruments.com/

 

[Nium]

In addition to Klein, Sears also sell TLS (torque limiting screwdrivers). Definitely get it calibrated once a year and keep the record that you did.

 

[jmellc]

In reference to the (Un)popularity of such a tool, aside from being forced to use one (Job spec), I think it mainly depends on the type of individual you are. I like taking the guess work out of situations in my life, whether that is doing electrical work or cooking or whatever. To me, a torque spec is concrete, set it and forget it, I don't have to worry about it later on when I hit the sheets. I tend to worry about stuff that can impact others so if I do it by the book I have less to think/worry about which also saves time and stress, plus I like to do things the right way. No one can fault you down the road for that.

Zog, do you know of a place I can send this to be calibrated? Do I send it back to Klein?

I understand that thinking too. But with this particular issue, I've have no real problems. I did learn a few years ago that threads can be stripped by overtightening. I quickly learned the "feel" when something is approaching its limits. I might use one myself if they were on the shelves. I like to have all I need and tool sellers love to see me come in. That's been the exception to me though. I have chain pliers for chandelier chain, screwdrivers from jeweler size to King Kong monsters, channellocks up to 480, etc.

 

[Volta]

...

If so, approx. how much does it cost?

This, at $236, is the lowest price of the three distributors suggested from your link.

If I were to venture a guess, I'd say I tighten over spec far more often than under.

You're not alone . . .

 

[Cow]

The breaker (Siemens) has the same type of terminal setup as their ground bars but recommends 25 in lbs, what's up with that?

I think Siemens needs to follow their own instructions. I can't count how many times I've barely(or not) gotten the screws out holding the jumper wire between the neutral and ground bars. It's so tight it's rediculous.

 

[mivey]

I think Siemens needs to follow their own instructions. I can't count how many times I've barely(or not) gotten the screws out holding the jumper wire between the neutral and ground bars. It's so tight it's rediculous.

That was done in a controlled environment, not out in the field with all of us ECs banging around in the panels like cavemen. :grin:

 

[jmellc]

For $236, I can surely do without this tool. If I get any real money coming in for some time, I MIGHT think about it. That's more money than I paid myself last year.