Test Question

[FrancisDoody]

What size conductor is required for a 40 amp baseboard heater supplied with 240 volts?

I say that a #6 is required. The calculated load is 50 amps. I believe that you must use the 60 degree table for your conductors, which would put you at a # 6 wire.
See the book states #8 conductors is the correct answer. We know there have been errors in Stallcup's books before.

 

[Dennis Alwon]

Is the feeder run in NM cable. If not you would use the 75C column if the wire is either 75C or 90 C

 

[FrancisDoody]

It was not stated. No more information was given. That is why I believe you should use the 60 degree column.

 

[svthard]

110.14 C

110.14 C

I believe the 60 degree is called for under a 100 amps, but is there a rating on the baseboard heater

 

[Dennis Alwon]

I believe the 60 degree is called for under a 100 amps

If the breaker is rated 75C and all the terminations are rated 75c, and most are, and you are not using romex than you can use 75C rating. 90C may be used for derating.