wire size for electric heater in air handler

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Old 12-13-09, 05:43 PM
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wire size for electric heater in air handler

Hello all,

I am installing a 10kw 220v heater strip in my air handler to give back up heat for the heat pump. The manufacture requires 60 amp breaker in the panel. I want to know what size wire should I run from the panel to the air handler, its about a 25' run. I think #6 will work but wanted to make sure that that is okay.

I calculated the amps to be 41.66 for the heater and over current protection for that would be 52 amps, thus the 60 amp breaker. And the #6 wire is rated for 55 to 60 amps. Would this be okay or is this to close?

Also, if I have to use #4 could I run 2 #10 wires for each phase (4 wires total plus a ground) instead of the single #4 for each phase.

Thanks, MRT19
 
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Old 12-13-09, 06:00 PM
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Since heating circuits must be designed to 125% of full-load the #6 is fine along with the 60 ampere circuit breaker. The 25 foot distance does not require any upsizing for voltage drop. You may NOT parallel anything smaller than 1/0 conductors for field wiring.
 
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Old 12-13-09, 06:55 PM
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The 16mm˛{ #6 } will work but a nice gotcha is are you running with SE cable or THHN/THWN in conduit ?

That may affect the rating but due both are copper I think you should not have any issue with it.

Also, if I have to use #4 could I run 2 #10 wires for each phase (4 wires total plus a ground) instead of the single #4 for each phase.
Unforetally you can not parallel any conductor smaller than 55mm˛ { #1/0 }any larger then it is not a issue

Merci.
Marc
 
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