Did I buy the wrong wire????

[oba97]

I'm preparing to install a farenheat 5000 watt heater in my garage. I ran 8/2 nm wire thinking it was fine. I downloaded the manual for the heater and it says to use wire rated for at least 75deg. I believe NM is only 60? Did I just screw up?

 

[n8n]

Any current production NM is actually NM-B which is 90C rated. Have a look at the jacket on your cable.

 

[oba97]

I'll take a peak, I just bought it yesterday so should be fine. Now my concern is I have it connected to a line that was installed with the house in 1978. It white ettcoflex 8/3 nm.

 

[oba97]

Heres a pic

 

[n8n]

well the old stuff is only NM, but I'm guessing the instructions are likely only concerned with the wire immediately connected to the device, not the entire length of the run feeding it. Now if you were bringing your entire house up to current code you'd have to repull the whole thing with NM-B but if you do not anticipate high ambient temperatures near it and the insulation appears to be in good condition, you should be fine with what you have.

 

[oba97]

Ok, thanks for the info. Is the main issue I could have is melting the insulation? Just wondering what I should look for upon start-up.

 

[pattenp]

For a 5000 watt heater you should only need #10. Did the instructions say to use #8? The insulation on NM is fine for 75 deg C. The NEC just limits the amp sizing for NM to 60 deg C.

 

[oba97]

I already had half a run or 8guage from an old stove. I just tied into that to finish the run vs running 75' of 10 guage.

 

[Speedy Petey]

The wire connecting directly to the heater must meet this temperature rating. The branch circuit can be lower.