Feeder amp rating
- Thread starter LincHawk
- Start date
- Status
- Location
- Bremerton, Washington
Please see section 240.4 (C)
- Location
- Bremerton, Washington
Who did the plans?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
To provide an accurate answer we would need to know what the calculated load is and if there is a single 1200A service disconnect or multiple.
Also you said "feeders" is this a service?
I am not sure what the total calculated load is.
We are going to replace an existing 1200A main disconnect that is setup delta currently with a new 1200A main that is setup wye. So we are adding a neutral. This only feeds up out of the main to a bus duct and that is all that is being fed off of the main.
I believe the existing feeders were also 500 mcm when we looked at it. So maybe that’s why they were called out on the new?
Sent from my iPhone using Tapatalk
We are going to replace an existing 1200A main disconnect that is setup delta currently with a new 1200A main that is setup wye. So we are adding a neutral. This only feeds up out of the main to a bus duct and that is all that is being fed off of the main.
I believe the existing feeders were also 500 mcm when we looked at it. So maybe that’s why they were called out on the new?
Sent from my iPhone using Tapatalk
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
So the conductors you are talking about, are they the service conductors or feeders?
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Since the single OCPD is 1200 amps you need 1200 amps or more worth of conductors. No way around that.
WA_Sparky
Electrical Engineer
- Location
- Vancouver, WA, Clark
- Occupation
- Electrical Engineer
Id personally do as mentioned above size 1200A OCPD with 1200A or more feeder above. Question to the crowd. Hypothetically if this was in an industrial application would 240.91 B apply? Then it technically would comply with code unless this article is meant for equipment rather than service entrance of industrial.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
I concur. OP please don't use the term "service feeder" or refer to service conductors as feeders, it is very confusing.
This is a secondary service conductor from a utility company transformer for an industrial facility. The service Main is a single 1200A. What’s there currently is (3) sets of 500 mcm.
So the existing 1200A service has (3) sets of 500 mcm. This is also what is called out to be replaced with new, except a neutral is being added to the service.
Everything is being replaced as is currently exact the neutral is being added.
My original question was can we install (3) sets of 500 mcm on this 1200A main? I didn’t know if there was some exceptions or other calculations that would allow this?
Sent from my iPhone using Tapatalk
So the existing 1200A service has (3) sets of 500 mcm. This is also what is called out to be replaced with new, except a neutral is being added to the service.
Everything is being replaced as is currently exact the neutral is being added.
My original question was can we install (3) sets of 500 mcm on this 1200A main? I didn’t know if there was some exceptions or other calculations that would allow this?
Sent from my iPhone using Tapatalk
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
No you cannot. It was very very common in the past to call this setup "close enough", or use the next size up rule above 800 amps, or whatever the thinking was, who knows.....
texie
Senior Member
- Location
- Fort Collins, Colorado
- Occupation
- Electrician, Contractor, Inspector
I sort of wonder why there was no neutral in the original install unless it was originally a corner grounded or ungrounded delta service.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Probably was, OP said existing was "Delta"
- Status