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View Full Version : Warm breakers, how much is too much?


Terry Beck
10-31-2012, 09:26 PM
Pair of 60-amp double-pole breakers for an electric force air furnace. Both were warm to touch when the furnace was running. My infra red thermoter showed 92-114 degrees. Side note, the panel is in an old basement, so the ambient temp was in the 60's.

I have only see a couple of electric furnaces before, so don't know if this is unusual. Didn't see anything else alarming in the wire run or at the furnace.

How warm would be considered to be too warm?
Marc M
10-31-2012, 09:48 PM
Pair of 60-amp double-pole breakers for an electric force air furnace. Both were warm to touch when the furnace was running. My infra red thermoter showed 92-114 degrees. Side note, the panel is in an old basement, so the ambient temp was in the 60's.

I have only see a couple of electric furnaces before, so don't know if this is unusual. Didn't see anything else alarming in the wire run or at the furnace.

How warm would be considered to be too warm?

HVAC always hotter than ambient when they are running. Just curious, What was the ambient temp when you took the disco temp?
Terry Beck
10-31-2012, 10:04 PM
Hey man, back in dem days of disco, I was HOT!!!. Me and Travolta. Boy oh boy.
Sorry. long day.
Ok - so what is a disco temp? I probably didn't take it.
Marc M
10-31-2012, 10:12 PM
Hey man, back in dem days of disco, I was HOT!!!. Me and Travolta. Boy oh boy.
Sorry. long day.
Ok - so what is a disco temp? I probably didn't take it.

What was the ambient temperature when you measured the HVAC breaker.
Terry Beck
11-01-2012, 01:31 AM
As I said originally

Side note, the panel is in an old basement, so the ambient temp was in the 60's.

So we're talking about a rise of 40-50 degrees on the surface of the breaker as compared to surrounding air.
Terry Beck
11-01-2012, 01:35 AM
As it is, I am already calling out a long laundry list of other items that need the attention of an electrician. The property is originally 1916 with old barns, shops, tack rooms, pump houses. Lot's of places for Grampa Ned to screw up the wiring.
Marc M
11-02-2012, 09:08 PM
As I said originally

So we're talking about a rise of 40-50 degrees on the surface of the breaker as compared to surrounding air.

It was pulling a load, of course it will be hot.
Ken Rowe
11-02-2012, 09:53 PM
No more than 35 degrees above ambient.
Raymond Wand
11-03-2012, 05:20 AM
Ambient temperature rating will depend on breaker manufacture, but the temp should be on the breaker itself.

Without knowing make of breaker, its a guess at the very least.

Temperature Derating for Circuit Breakers (http://www.bdbreakers.com/breakertypes.php)

Frequently Asked Questions (http://www.schneider-electric.us/sites/us/en/support/faq/faq_main.page?page=content&country=US&lang=EN&locale=en_US&viewlocale=en_US&id=FA97458&redirect=true)