Question ????

Should I or would you be concerned about a 10 degree temp differential between the two legs on a 240 volt double pole breaker Yes or no please

Yes.

Ok I am gathering yes and no’s lets see who wins

No. I wouldn’t be too concerned because 240V loads are not always perfectly balanced and 10 degrees F isn’t very much of a difference. You might first want to look at what type of load it is. You could also put a clamp-on Ammeter on each leg to see if there is much of a difference between the two legs. Also look for loose connections. If the load is a 240V heating element or something similar, the legs would have exactly the same current flowing. One being hotter than the other would suggest a loose connection. One the other hand, some appliances have both 120V and 240V loads. At any given time, one leg could be carrying more or less current than the other so one leg could be hotter than the other.

A loose connection would be localized to the connection, no?
Any way you look at it, it’s a possible deficiency that warrants investigation.

Ok one yes and one no

The appliances that have 120 volt circuits are mostly for clocks and timers that virtually have no amp draw not enough to effect the infrared temp

Are you sure think about what you are saying. Just asking:D:D

I would need to be there to make the call.:stuck_out_tongue:

No big deal I agree with George .
I think you will find this is very common . Roy

Are you absolutely sure this is very common;-):wink: I take that for a no

one yes and two no’s

yes [size=2]If we are talking about a feed to a sub panel[/size]
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I did not say what the breaker was feeding but it was not feeding a sub panel I will give more specifics after I collect a few more yes or no’s

The motor on a dryer is 120.

If it is feeding a balanced load then I would expect they should both be very close to same temp.

I have to respectfully disagree with that one Charlie. I’ve recorded my highest temps at 900+F and 600+F on 120v circuits.

BTW: Is that a split buss I see? What kind of load is on each leg? Tell me more about that hot spot on the buss.

Nine hundred degrees? Six hundred degrees? The insulation must have cooked off a long time ago at those temperatures. I am surprised the house was still standing.

And the heating elements are 240V … which gives you an ubalanced load on the hot wires.

Correct, a previous post made it sound like only loads like timers and light bulbs were 120 and would not make a significant difference in the amp draw or temperature.

The 900+ degree temp was at a poor connection on a double lugged grounded conductor. There was little left of the insulation other than ash and the conductors were blackened. I didn’t need IR to find this one.


The 600+ was more insidious. New construction, light load on an AFCI circuit. Hot spot was very localized at the terminal, but would have conducted further out if given time. The insulation was nicely browned near the terminal, but was concealed behind a cluster of wires. The electrical contractor never tightened down the screws on the terminals. I would not have found this without IR.

http://www.houstonthermalinspections.com/system/files/images/IR_2094.preview.jpg

And why not just use an infrared laser thermometer to scan the breakers in like 2 seconds … somebody has a new toy … :wink: