electrotanman
Member
Can I install a 50 amp breaker on an 8/3 NM cable ? Changing out a piece of equipment with a draw of 45 amps. Or do I have to upgrade the cable ?
nafis said:nm 8 is rated 4o amp @ 60deg and 50 amp @ 75
What kind of equipment? Is anything in the specs about supply requirements?electrotanman said:Changing out a piece of equipment with a draw of 45 amps.
DavidA said:While I agree the cable should probably be replaced, I'm wondering why you can't use the 75 degree table in this situation.
334.80 Ampacity.
The ampacity of Types NM, NMC, and NMS cable shall be determined in accordance with 310.15. The ampacity shall be in accordance with the 60?C (140?F) conductor temperature rating. The 90?C (194?F) rating shall be permitted to be used for ampacity derating purposes, provided the final derated ampacity does not exceed that for a 60?C (140?F) rated conductor. The ampacity of Types NM, NMC, and NMS cable installed in cable tray shall be determined in accordance with 392.11.
I disagree with AHJ, 50' doesn't have much Voltage drop and even if it did, 8/3 Romex is still only good for 40Amps as mentioned earlier. I believe you can use SE cablejute said:I'm in Calif and in the process of hooking up an above ground spa. It's being inspected and the AHJ told me that I should use #8-3 with #10 ground FNMC connected to a 50/50 2 pole breaker. I was told this is ok as long as it's under a 50' run??? Am I ok with this set-up??? Thanks JB
You can use SE cable; however, SE cable is required by 338.10(B)(4)(a) to comply with the installation requirements of Part II of Article 334. 334.80 (which is in Part II) requires the ampacity to be at the 60? C level so the 8 AWG SE cable is still only good for 40 amperes where used inside.jmsbrush said:I believe you can use SE cable
fisherelectric said:"only good for 40 amperes where used inside. " Why "inside"?
fisherelectric said:This must be another change in the '08 Code.
infinity said:Take a look here:
jute said:I'm in Calif and in the process of hooking up an above ground spa. It's being inspected and the AHJ told me that I should use #8-3 with #10 ground FNMC connected to a 50/50 2 pole breaker. I was told this is ok as long as it's under a 50' run??? Am I ok with this set-up??? Thanks JB