130 degree Far. 3pole Square D bolt on breaker.

[esharped]

Hello,
I hope this is the right forum for this question.
I just installed a new circuit for air handlers.
Three number 8 thhn and number 10 ground thhn
and a 50 amp 3 pole Square D breaker.
The circuit draws 30 amps and runs 24/7.
Is 130 degrees to hot for this breaker?
Should I be worried I have had it running
for 5 days now?
Thanks to anyone who can answer these questions,
Sam Crosby

 

[Jraef]

How are you determining the temperature, with an IR gun aimed at the terminals or a thermometer in the panel?

If that is the air temperature from a thermometer in the panel, that would be too hot. Panels and breaker ratings are all based on 25C (77F) for calibration and 40C (104F) max ambient. Higher than that and the trip values are no longer valid, which may result in improper protection of the circuit.

If on the other hand you are using an IR gun looking at the hottest spot on the breaker, usually the top most lug, then this is borderline acceptable. As a general rule, the breaker components are typically designed for 50-55C rise, which means ABOVE the ambient design temperature (the 25C I mentioned earlier). So that means if you are looking directly at a spot on the breaker, the general rule of thumb is to use the rated rise as the maximum hot spot. So at 130F you are already at roughly 55C. At best, you are on the ragged edge, assuming your panel ambient is no more than 25C (77F). If the panel ambient air is hotter than that, and/or your breaker is designed for a 50C rise, you are in trouble.

 

[esharped]

Thanks

Thanks

The tempuature of 130 Far. is the hottest spot on the breaker.
I used an infrared thermometer. It's # 8 thhn and only running at 28 amps for three motors.
should I up the wire to #6 awg? I still do not understand why 30 amps could make it so hot.

 

[tom baker]

What are the other terminals temp reading? Doesn't matter too much what the individual reading is but rather the comparsion between them.
Some times when you tighten the lug it can twist and become loose from the fastener on the back.

 

[jim dungar]

Where on the breaker are you reading 130?F?

Typically the lugs should be cooler than the operating mechanism which can reach 60?C (140?F).