8 gauge range feed

dhsvcs

Member
Location
miami
Occupation
electrician
Can I use 8 thhn wire with a 75 degree rating to feed a range receptacle ?

Also, I am involved with a remodel of an existing 8 unit apartment complex and am helping the PE get his load calcs low
as possible...
I am trying to keep the existing underground service feed ( at least using only the existing 3" u.g. conduit) while adding central air conditioning to the existing apts.
Most of the apts are less than 650 sq ft with an existing 100 A load center. To keep the total load calc low, what is the minimum size
range that I can use ? When multiplying by 8 ranges, it adds up..
I will calculate the loads using both the optional and standard method, although I am sure the optional calc SHOULD have a lower total.
The building will have a common dryer/washer, so I won't need a laundry circuit ...

Thanking you for your help & any suggestions...
DHSVCS
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
What is the size of the OCPD and what is the type of wiring? If it's MC cable you can use the 75° C ampacity of #8 which is 50 amps. Many ranges only require a 40 amp branch circuit.
 

kwired

Electron manager
Location
NE Nebraska
Unless you have higher than 12 kW ranges the demand calculation is 8 kW for each range circuit, and this 8 kW is added to feeder calculation to individual apartment also.

You don't multiply that by 8 for the service (which would be 64 kW), you go further down the table and see that the service will have an allowable demand of 23 kW for 8 ranges of 12 kW or less.

40 vs 50 amp individual range circuit(s) doesn't change this.
 

bzzt

Member
Location
mn
Occupation
wirer
Can I use 8 thhn wire with a 75 degree rating to feed a range receptacle ?

Also, I am involved with a remodel of an existing 8 unit apartment complex and am helping the PE get his load calcs low
as possible...
I am trying to keep the existing underground service feed ( at least using only the existing 3" u.g. conduit) while adding central air conditioning to the existing apts.
Most of the apts are less than 650 sq ft with an existing 100 A load center. To keep the total load calc low, what is the minimum size
range that I can use ? When multiplying by 8 ranges, it adds up..
I will calculate the loads using both the optional and standard method, although I am sure the optional calc SHOULD have a lower total.
The building will have a common dryer/washer, so I won't need a laundry circuit ...

Thanking you for your help & any suggestions...
DHSVCS
Typically you need to read the temperature rating on the breaker. Many breakers are rated for 60* thus reducing the allowable ampacity
 

kwired

Electron manager
Location
NE Nebraska
Typically you need to read the temperature rating on the breaker. Many breakers are rated for 60* thus reducing the allowable ampacity
Old breaker maybe. All the breakers made by today's main four manufacturers are all 75C AFAIK.

New receptacle outlets of the type typically used here are also 75C from what I have seen.

This been the case for at least 20 years and many items been that way for 30 or more years.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
There haven't been 60° C rated circuit breaker terminals in decades at least none that I have ever seen.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Can I use 8 thhn wire with a 75 degree rating to feed a range receptacle ?

I will calculate the loads using both the optional and standard method, although I am sure the optional calc SHOULD have a lower total.
The building will have a common dryer/washer, so I won't need a laundry circuit ...

Thanking you for your help & any suggestions...
DHSVCS
I am pretty certain that a #8 is fine even at 60C.

Don't bet on the optional vs standard. The optional is generally lower however with multifamily that can change quickly
 
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