70 amp wire on 50 amp max breaker size?
Shouldn't that read 50 amp load at 125%
so wire and breaker rated for 70 amp?
70 amp circuit 50 amp recept. gfi?
- Thread starter ritelec
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Shouldn't that read 50 amp load at 125%
so wire and breaker rated for 70 amp?
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
What is the model number and brand?
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
See post #16 (the screenshots match that manual exactly). Wayne
So I just say down going through The link you sent. Thank you again got that.
So riddle me this.
Page 10.
The terminals are rated 105c with a max wire size of #6 awg. Is that saying you would need to use # 6 and rate at the 90 degree column? Then increase the wire size at some point for connection to the circuit breaker if wiring for over 60 amp ?
So riddle me this.
Page 10.
The terminals are rated 105c with a max wire size of #6 awg. Is that saying you would need to use # 6 and rate at the 90 degree column? Then increase the wire size at some point for connection to the circuit breaker if wiring for over 60 amp ?
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
#6 Cu has a 75C base ampacity of 65A. So with it, you could set the EVSE to 50A, as 125% * 50A =62.5A < 65A. And you could use a 70A breaker with 75C terminals, as 65A is not a standard breaker size. No need for changing wire size.
Cheers, Wayne
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
You cannot use the 90C for determining ampacity except when you are de-rating.
I was just typing what Wayne wrote--but I will add that 240.4(B) allows the 70 amp breaker as long as the load is not more than the conductor rating. In this case it is 62 amps and the conductor is good for 65 amps.
This all goes away if you are using nm cable which must be rated at 60C
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