ECN Forum Forums Code Related Discussion NEC & other Code issues Torque Screwdrivers

the code says that terminals should be torqued as listed by the manufacturer...

i beleive that this can not be accomplished by a manual screwdriver, and must be done using a torque screwdriver.

it is probably not enforced much but while in wyoming it was required by the state.

since then i have pretty much agreed that this is a very good rule becasue it helps assure proper tightening of the terminal..

terminations are critical on the stuff i am working on

If a torque value is shown for any termination, they mean for you to use it. After all, it is a part of the "Listing & Labeling' in 110-3(b).

I have two torque wrenches & a torque screwdriver. When I got the screwdriver, I ran a little experiment. I had electricians tighten the screw on a Square D 1 pole 20, listed torque value of 35 in/lbs, highest of all 1 pole breakers. Most guys tightened the screw to 25 in/lbs, which means they were 28% shy of the correct value. No one ever made it too tight.

Next, I set the screwdriver to 35 in/lbs & let them try it. They all thought the screw was about to strip out.

Personal experiance has shown that 25 in/lbs on a Square D single pole 20 breaker is tight enough, but that doesn't make it right.

Tom

Tom, What brand is your torque screwdriver? Where did you get it? I have a 3/8" drive "clicker" torque wrench that is calibrated for inch pounds but have not had much luck finding a torque screwdriver that was much count.

Fred,

Mine is a Klein. Seems to be pretty well built, haven't found any reason to fault it. Be prepared to cough up $125 +++ (based on what I paid 2 or 3 years ago).

Tom

try a klein