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Discussion Starter · #1 · (Edited)
Q1: I have been under the impression that I could not use a 50A breaker with a #8 wire. (Romex, NMB) I usually run 8/3 Romex for ranges and use a 40A breaker. - However, can I use a 50A breaker. - I am thinking no because the range would be considered a continuous load. (Does the NEC state anywhere that it is a continuous load?... Most likely all the elements would not be used at the same time at maximum load for more than three hours. It seems that, years ago, I talked with an inspector regarding this and I thought he told me, for some reason, that I couldn't use a #8 with a 50A breaker for a range. Why he might have said this I do not remember... (In fact it was so long ago that I can't even remember for sure if he, in fact, did say this.)

Q2: I am looking at installing a new sub panel in a garage for a customer and I am thinking that a 50A breaker with #8 will do the job... However, again, I was under the impression that I couldn't use a 50A breaker with a #8 but after looking in the code book further I don't see why I wouldn't be able to.

Anyone care to help me clarify this? Thanks in advance.
 

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You cannot use 8/3 NM on a 50A breaker. You must use the 60 degree column when sizing your conductors. You could put #8 THHN on a 50A breaker however. The range is not a continuous load.
 

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Discussion Starter · #3 ·
Okay, got it. - I sincerely appreciate that reply. Can you explain to me why I have to use the 60 degree column? I am not asking this to question your answer, I just really hate not knowing the reasoning behind things. I opened my own business about a year ago and I am learning sooooo much... (You are forced to when you don't have others to rely on.) Is all NMB calculated using the 60 degree column?
 

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Okay, got it. - I sincerely appreciate that reply. Can you explain to me why I have to use the 60 degree column? I am not asking this to question your answer, I just really hate not knowing the reasoning behind things. I opened my own business about a year ago and I am learning sooooo much... (You are forced to when you don't have others to rely on.) Is all NMB calculated using the 60 degree column?
334.80 Ampacity. The ampacity of Types NM, NMC, and NMS cable shall be determined in accordance with 310.15. The  ampacity shall not exceed that of a 60°C (140°F)   90°C (194°F) rating shall be permitted to be used for ampacity adjustment and correction calculations, provided the final derated ampacity does not ex- ceed that of 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 392.80(A).
For your subpanel, just use a piece of aluminum SE cable.
 

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Discussion Starter · #6 ·
Great! - Thanks.... I really appreciate the replies. For me, this forum is a great resource and I appreciate hearing from you.
 

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Okay, got it. - I sincerely appreciate that reply. Can you explain to me why I have to use the 60 degree column? I am not asking this to question your answer, I just really hate not knowing the reasoning behind things. I opened my own business about a year ago and I am learning sooooo much... (You are forced to when you don't have others to rely on.) Is all NMB calculated using the 60 degree column?

How does one find themselves offering services when they don't know the basics?
 

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So since I run my range ckts in ENT, that would allow me to fuse #8s at 50 amp?
 

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If it is run that way the entire run. If you run 8/3, then change over to ENT, then no.
Stupid me, I have endless DP 50s stocked, I went out and bought DP40's . All I use is ENT for 30 and over appliance ckts.
 

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Just run 6/3 NM and you're good to go! My neighbor has a manufactured home with a 40 amp on the range circuit. I'm supposing it's wired with #8. She trips the breaker when she gets serious about cooking! If you're going to run the oven an 1 or 2 burners you might get by.
 
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