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-   -   Torque and Temperature (https://www.diychatroom.com/f18/torque-temperature-59236/)

hunterthompson 12-14-2009 07:28 AM

Torque and Temperature
 
Hello All.

I installed my meter socket and subpanel a few months ago, when it was about 65 or 70 out.

I went out yesterday to check things as the Electric Company is coming out tomorrow to hook me up to the pole.

Anyway to make a long story short I ended up tightening my connections because they all seemed to need it. I used the torque wrench and everything is set where it is supposed to me. The difference is that it was about 25 degrees when I did it this time.

My question is; Is torqueing at this temperature going to cause problems when the summer comes again or when the juice is flowing through the wires.

Thanks

Billy_Bob 12-14-2009 10:58 AM

I've never seen anything on the lug nut torque instructions about torquing to a different inch pounds at different temperatures. And electrical engineers are quite good at identifying problems and communicating exact procedures to prevent potential problems...

So in the absence of any specific instructions for torquing at certain temperatures, I would guess that it has never been a problem!

Also metal contracts when cold, expands when hot. I would assume if the metals of the wire and lug nut assembly have a similar coefficient of thermal expansion, then they would both expand and contract together. Or if using copper wire which has a higher number, I would think the connection would be tighter in the summer.

Coefficient of thermal expansion...
http://www.wisetool.com/designation/te.htm

Thermal expansion...
http://en.wikipedia.org/wiki/Thermal_expansion

Yoyizit 12-14-2009 02:35 PM

"if all of the materials of the joint and the bolt are the same then any changes in temperature will have negligible effect of the joint loadings.**However if the joint materials have coefficients of thermal expansion different to the bolt material changes in the joint loading result from changes in temperature..."

from

http://www.roymech.co.uk/Useful_Tabl...ng.html



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