Nm-b

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steve burke

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Wiring residential Thermolec 12KW electric boiler (B-12U FFB) with nameplate 47.92 amps and a specified 1x60amp breaker. Spec calls for “always use 75C(167F) min”.
Are we correct that 6/2 NM-B is limited to 55amps and 60C sheath. Therefore we cannot use NM-B and must use at least 6AWG cu in conduit?

As a side note, a conduit run is very time consuming given the 12” OC joists.
 
You just need 75C wire inside the unit so, you can set a disconnect at the unit and use 75C/90C wire from there
Thank you for the clarification. Since the breaker is specified by manufacturer at 60amps, i guess i am still stuck with conduit or MC cable since 6/2 NM-B rated for 55amps. Correct?
 
I would not hesitate to use aluminum SEU from the power source to the disconnect and then go copper into the unit. It would be cheaper
 
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