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Old 05-26-2009, 05:20 PM   #1
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Can anyone tell me if AFCI Breakers should get warmer than regular breakers. They are Ch Cutler Hammer.All the breakers are about 85 The AFCI Breakers Are 107. Did a amp test 0.8 amps on all three AFCI'S. Thank you

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Old 05-26-2009, 06:11 PM   #2
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Can anyone tell me if AFCI Breakers should get warmer than regular breakers. They are Ch Cutler Hammer.All the breakers are about 85 The AFCI Breakers Are 107. Did a amp test 0.8 amps on all three AFCI'S. Thank you
Is the surface area of your AFCI less than that of the others?
The one 20A CB that I autopsied had a 2w resistor in it for the thermal trip. If 2w causes a 85-30 rise above amb. then the thermal resistance is 28C/w. For the same thermal resistance the AFCI would be using up 107/28 = 4w. That's probably a reasonable power consumption to run all the circuitry inside one of these.

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Old 05-26-2009, 06:23 PM   #3
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Yoyizit. Thank you for fast reply. I think i found a reply on another forum this is what it said -
Yes, that's completely normal. The manufacturers say that they may have up to a 40 degree temperature rise over ambient. Sorta throws you for a loop, doesn't it?

For this reason, some installers prefer to leave a blank space or a regular breaker between groups of AFCI breakers. Keeps them from heating each other up so much. Give a little room in between to cool off. This isn't expressly required by any manufacturer, but some installers consider it good practice.
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Old 05-26-2009, 06:32 PM   #4
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may have up to a 40 degree temperature rise over ambient.
At rated current; you were drawing way less than that, which throws off my thermal resistance calc's.

Can you imagine the case of a CB at 70C?

"burned in 30 sec at 54C
5 sec at 60C
1 sec at 71C"

Last edited by Yoyizit; 05-26-2009 at 08:12 PM.
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