Torque wrench on lugs

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Old 01-04-06, 08:38 AM
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Torque wrench on lugs

If I recall, the code and other sources say that the main lugs on my new subpanel must be tightened to 50 lbs./inch. I looked into buying a torque wrench and will if necessary, but they aren't cheap. I tightened the main lugs pretty tight, to the point that the strands of the #1 wire have all spread out.

The electrician who installed my new main panel said that he knows how tight it has to be just by feel. However, I don't have his experience and was wondering if there was some way to tell if I am tight enough on my subpanel. Is there a danger of going too tight?
 
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Old 01-04-06, 09:16 AM
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Originally Posted by Tyger52
If I recall, the code and other sources say that the main lugs on my new subpanel must be tightened to 50 lbs./inch. I looked into buying a torque wrench and will if necessary, but they aren't cheap.
If you have an electric drill with an adjustable torque setting, you might check the manual to see if the settings are calibrated to particular torque levels. Presuming the panel is not energized, then you could put a hex bit in the drill, set the clutch to the appropriate position, and torque the head until the drill disengages. Also I think torque is measured in in-lbs.
 
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Old 01-04-06, 09:16 AM
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If you don't yet have the feel, you should probably get a torque wrench. But if you think of tightness as "snug", "fairly tight", "tight" and "really tight", then 50 inch-pounds (not pounds/inch) falls somewhere between "fairly tight" and "tight", definitely not "really tight" (which is what you'd put the wheel lug nuts on your car with).
 
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Old 01-04-06, 03:03 PM
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I used to think that I was tightening lugs correctly by feel. Then I bought the torque wrench and correctly applied the required torque. To my surprise my hand tightened lugs very over tight.

This requirement is not specd in the Code, however it is a requirement the the equipment be installed by following the manufacturers directions.

PS too tight will create a hot spot on the conductor.
 
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