NEC or Product Manual?

cdillman7 · Mar 15, 2021

I posted this on a different forum but didn't get a lot of discussion so resharing this here for more feedback.

My friend bought a 10kw Comfort Zone Electric Heater

(see: https://www.amazon.com/Comfort-Zone...er+cz269er+10000+watts&qid=1615526178&sr=8-13)

And I'm trying to figure out conductor size and overcurrent protection for him.

With Ohms law I get 10kw at 240v = load size of 41.67 amps.

According to NEC Article 424 Fixed Electric Space Heating Equipment, this ceiling mounted electric heater is a continuous load. And must be multiplied 125 % of the load = 52.0875 amps. I emailed the manufacturer what amps the blow motor is rated at but haven't gotten a response yet. Regardless - 6/2 Romex is rated at 55 amps and the next closest Overcurrent Protection Device (Curcuit Breaker and separate Disconnect) would then theoretically be at 60 amps.

I read the manual and it doesn't mention continuous loads (seems to ignor it completely). Can't figure out how to upload pictures of manual but it only say that the device is at 10kw, 240V 69 Hz, Phase1, 41.67 amps and BTU/Hour: 32, 122. Wire should.be copper at a rating of 75C, fuse size 50amps and min copper wire size at: 6AWG.

So which Breaker Size should I side with? The 50 amp according to the manual or should I use a 60 amp breaker as I calculated via the NEC?

I am also wondering if 4-2 Romex (6-2 Romex would be awesome if allowable) would be cheaper than running #6 THHN b/c of need for an EMT raceway.

Thanks for the help!

telectrix · Mar 15, 2021

according to our regs here, Ib<In<Iz, where Ib is the actual load current. In is the breaker rating, Iz is the max. current for the selected cable. so in your case, 41.67A Load)< 50A (breaker rating) < 55A (6/2 Romex max, current). so that would comply.

Megawatt · Mar 16, 2021

cdillman7 said:
I posted this on a different forum but didn't get a lot of discussion so resharing this here for more feedback.

My friend bought a 10kw Comfort Zone Electric Heater

(see: https://www.amazon.com/Comfort-Zone...er+cz269er+10000+watts&qid=1615526178&sr=8-13)

And I'm trying to figure out conductor size and overcurrent protection for him.

With Ohms law I get 10kw at 240v = load size of 41.67 amps.

According to NEC Article 424 Fixed Electric Space Heating Equipment, this ceiling mounted electric heater is a continuous load. And must be multiplied 125 % of the load = 52.0875 amps. I emailed the manufacturer what amps the blow motor is rated at but haven't gotten a response yet. Regardless - 6/2 Romex is rated at 55 amps and the next closest Overcurrent Protection Device (Curcuit Breaker and separate Disconnect) would then theoretically be at 60 amps.

I read the manual and it doesn't mention continuous loads (seems to ignor it completely). Can't figure out how to upload pictures of manual but it only say that the device is at 10kw, 240V 69 Hz, Phase1, 41.67 amps and BTU/Hour: 32, 122. Wire should.be copper at a rating of 75C, fuse size 50amps and min copper wire size at: 6AWG.

So which Breaker Size should I side with? The 50 amp according to the manual or should I use a 60 amp breaker as I calculated via the NEC?

I am also wondering if 4-2 Romex (6-2 Romex would be awesome if allowable) would be cheaper than running #6 THHN b/c of need for an EMT raceway.

Thanks for the help!

My friend all you need is cable rated for 60 amps and install a 60 amp double pole breaker. They have wire at Lowe’s or Home Depot that will be good for 60 amps. Good luck