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# Temperature of Electrical Box Under Load

## Temperature of Electrical Box Under Load

#1
12-03-13, 04:37 PM
Member
Join Date: Oct 2013
Posts: 487
Temperature of Electrical Box Under Load

I picked up a handheld infared thermometer... just a cheap 12 dollar one. I have been putting it thru the paces around the house. Checked out a stuffed electrical box.

Under load I was getting somewhere in the region of 75'-80' degrees. After the load was removed after some time there was about a 5 degree difference when it cooled.

What do you think is a normal temperature for the contents of an electrical box? How does it relate to the 60c and 75c ratings on wire insulation? Do you think a 5 degree swing when under load is adnormal heating?

I know this one might be hard to answer.....

#2
12-03-13, 04:57 PM
Member
Join Date: Mar 2012
Location: USA
Posts: 7,458
I know this one might be hard to answer.....
Why?

75'-80' degrees. After the load was removed after some time there was about a 5 degree difference when it cooled.

What do you think is a normal temperature for the contents of an electrical box? How does it relate to the 60c and 75c
Let me guess: You're reading [SUP]o[/SUP]Fahrenheit and asking about [SUP]o[/SUP]Celsius, right?

Do the math. They're not even in the same ballpark.

#3
12-03-13, 04:59 PM
Member
Join Date: Oct 2013
Posts: 487
I should have clarified... yes my read is F. And I dont know how ambient air effects this....

As far as a temperature swing of wiring in general... under load should they be the same temp as not under load?

#4
12-03-13, 05:29 PM
Forum Topic Moderator
Join Date: Jul 2002
Location: Maryland
Posts: 13,970
The higher the load on the wiring will result in a higher conductor temperature. Ambient air does not affect the temperature rise, but will affect the thermal part of the breaker. OLnce the thermal portion detects too much heat it will trip. A breaker outside on a cold day would take longer to trip than the same breaker on a hot summer day under the same load.