I'm hoping someone can help with this question. We are installing an electric wall furnace, 240 volt, 38 amp, 9.2kwh. I was told by the guy at the hardware store to use size 8 wire. The instructions (?? ) that come with the unit don't sat anywhere what size is to be used! Is size 8 wire correct?
Thanks,
Mel

The wire size needs to be rated not less than 125 % of the nameplate load.

9400 watts / 240 volts = 39.17 x 125%= 48.96 amps

If you use NM-B Romex, then the smallest wire can be #6 copper.

Only if you use MC cable, or pull THHN wire through conduit, then #8 copper THHN can be used.

A 50 amp breaker is needed.

Thanks TKrussell. Wired it up with NM-B Romex #6 copper with 50 amp fuse, and it seems to be working OK. Thanks for the quick response!

My only concern now is that even when not blowing or heating, the heater has a quiet hum sound. Does anyone know if this is normal? The heater is a Dayton model TYV14.

Thanks,

Melody