Electric furnace

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Rsemp

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Oklahoma
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Electrician
Three electric furnaces, one is 80’ from panel the other two are closer. All three have two- 2 pole 60amp breakers, will 6/2 romex be sufficient to each breaker?
Thank you.
 
With romex it will depend on the MCA of the unit. The Romex must have a 60°C ampacity no less than the unit MCA. For #6 55 amps would be the max allowed.

(A lot of electric furnaces use a 60 amp as a disconnect so don't let that breaker guide you. Check your nameplate MCA, MOCP)
 
One thing I noticed is the wire on the load side of the 60 amp breaker is #10 feeding the heat strip, not sure if that makes a difference. I haven’t had a chance to look at the MCA.
 
Rsemp said:
One thing I noticed is the wire on the load side of the 60 amp breaker is #10 feeding the heat strip, not sure if that makes a difference. I haven’t had a chance to look at the MCA.
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It might have a 60 amp breaker regardless the element watts it supplies. Some do size the breaker to the load others just use 60 amp - partly because that is allowed by both NEC and probably also by listing standards.

Elements are typically 4.8 kW max but they will put two of those on one 60 A circuit with a 10AWG off the breaker to each element.

Two 4.8 elements gives you 9.6 kW which @ 240 volts is 40 amps. That can be on a 50 amp breaker, if the blower happens to be on the circuit that puts you over and needing a 60 amp breaker. Too much blower or a little more heat than 4.8 might get you in trouble on the 55 amp limitation of 6AWG NM cable.
 
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