What wire and breaker needed?

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olly

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Berthoud, Colorado
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Master Electrician
I have a infrared sauna I am going to hook up. I cant get the manufacture to give me the specs as far as recommended breaker size. It pulls 47.5A.
They said to put it on a 47.5A breaker and use 8/3 HAHAHA

This should get a 60A breaker with 6/3 CU since I am using NM cable. Correct?
 
I’m with you! Can you pull up anything online using manufacture and model number? I would think that it is a continuous load 80% of 60 is 48 amps. Or 47.5/.8 v 59.4 amps or 60 amp breaker!
 
Would not expect a sauna to be a continuous load, as it cycles on and off once up to temp and most people don't sauna for 3 hours unless this is some group situation with people always going in and out. Would think #6 NM on a 50A breaker is fine.

Is this cord and plug connected? That should provide some clue as to true load and if a neutral is needed.
 
I agree probably not a continuous load so a minimum 50 amp branch circuit.
 
infinity said:
I agree probably not a continuous load so a minimum 50 amp branch circuit.
Click to expand...
So can I use #8 CU NM cable considering 240.4 B on a 50A breaker? I get confused with, you have to use the 60 degree column when using NM and how 240.4 B comes into play - you can use the next higher standard over current device .
I would think the answer is no you cannot use #8 CU that = 40A in the 60* column, since the next standard ampere breaker would be a 45A. Correct?
I have a guy that is telling me you can use #8 CU in NM cable for a 50A breaker.
 
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olly said:
I would think the answer is no you cannot use #8 CU that = 40A in the 60* column, since the next standard ampere breaker would be a 45A. Correct?
I have a guy that is telling me you can use #8 CU in NM cable for a 50A breaker.
Click to expand...

#8 NM cable at 60° C is 40 amps so there is no next size up since 40 amps is a standard size. You can protect #8 MC cable at the 75° C ampacity of 50 amps because there is no 60° C limit on MC cable.
 
infinity said:
#8 NM cable at 60° C is 40 amps so there is no next size up since 40 amps is a standard size. You can protect #8 MC cable at the 75° C ampacity of 50 amps because there is no 60° C limit on MC cable.
Click to expand...
And you can't protect #6 NM at 60 amps for this either.
 
Don’t forget to factor in the distance from the panel to the hot tub, it might require de-rating to avoid a significant voltage drop. Ending up with low voltage at the tub can affect the pump motors.
 
olly said:
So can I use #8 CU NM cable considering 240.4 B on a 50A breaker? I get confused with, you have to use the 60 degree column when using NM and how 240.4 B comes into play - you can use the next higher standard over current device .
I would think the answer is no you cannot use #8 CU that = 40A in the 60* column, since the next standard ampere breaker would be a 45A. Correct?
I have a guy that is telling me you can use #8 CU in NM cable for a 50A breaker.
Strathead said:
And you can't protect #6 NM at 60 amps for this either.
Click to expand...
I would do what Infinity stated by using MC, in which, #8 at the 75 column is good for 55 Amps, as long the terminals are rated for 75 C but it could come down to cost
Click to expand...
 
What about the connections at the sauna? Lugs? Temp. rating?
 
Amps said:
What about the connections at the sauna? Lugs? Temp. rating?
Click to expand...
You're correct that the terminals need to be considered but IMO we've come to the point where just about everything is 75°C and it's safe to assume so. If this were a test question then that would change the conversation.
 
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