Breaker size needed for 42 amps.

[Robby321]

Electric heater (shop, 220). 10,000 watt, 42 amp draw. 50 amp breakers OK? From what found, seems right. What I have now welder..thanks.

 

[Captain Spaulding]

What size is the wire running from the breaker to the equipment?

 

[Robby321]

8-3 with ground

 

[Norcal]

8-3 with ground

Too small, 8/3 NM 40A maximum.

 

[sberry]

6/2 50

 

[Robby321]

OK, I'll have to look into this a bit more. What about a 7500 watt? But what found, wants 40 amp breakers. Run with 50's?

 

[wyliesdiesels]

10Kw heater will need 50a breaker with either #8 THWN in pipe or 6/2 NM-b

7.5K heater will need 40a breaker with either #8 THWN in pipe or 8/2 NM-b

BTW elec heat is expensive to operate.

EDIT: i incorrectly estimated in my head the continous load sizing.

Will need 60a breaker with #6 wire (either 6/2 NM-b or #6 THWN)

 

[md21722]

OP is in Washington state, between the BPA and the Grand Coulee Dam, its the cheapest electric in the country.

 

[Robby321]

OP is in Washington state, between the BPA and the Grand Coulee Dam, its the cheapest electric in the country.

Yep..but getting old and still use wood stove shop (dry heat shop toys and tools, rust PNW rainy season) but the hassle getting wood says maybe new. No Nat Gas here, just propane and a tank, heater installed be 2 grand easy. Just thinking ahead..attached shop to house off a enclosed porch. And I just about LIVE out here! My sanity and sanctuary "Dudgeon".

 

[Aceman]

42 amps X 125% for a continuous heating load = 52.5 amp minimum wire and breaker ampacity.

NEC 424.3(B)

 

[Robby321]

I'll have to get a electrician over here and see my options. Thanks replys!

 

[wyliesdiesels]

42 amps X 125% for a continuous heating load = 52.5 amp minimum wire and breaker ampacity.

NEC 424.3(B)

Yeah whoops i estimated the continous load ampacity. Shouldve grabbed a calculator...

#6 THWN will still work however.

 

[alfredeneuman]

.......and a 60 Amp breaker