What size service is this ?

[Ponchik]

Do manufacturers make a 350A rated service? Or one has to install a 400A rated service with a 350A main disconnect or two disconnects with a rating not exceeding 350A?

 

[iwire]

Service size is the calculated 267 amps.

What the POCO calls it may be different - and likely will be in same classification as a full 400 amp service in most cases.

What the AHJ calls it for permit fees may also be different. This may very well be different in some AHJ's then others as well. Here there is a set permit fee for 0-100 amps, one for 101-200, one for 201-400, and I'd have to verify the higher figures, but it is in similar blocks of ampacity. So if done here, the OP's application would fall in the 201-400 and would be the same fee for any service value in the range.

If we were voting for the best, most logical answer kwired would have my vote.

Service size is different things to different people for different reasons. As 'service size' is not defined in any way it is simply a slang term that has little real meaning.

 

[kwired]

If we were voting for the best, most logical answer kwired would have my vote.

Service size is different things to different people for different reasons. As 'service size' is not defined in any way it is simply a slang term that has little real meaning.

I could have used those words in my earlier reply, that is exactly what I was trying to point out.

 

[Ponchik]

If we were voting for the best, most logical answer kwired would have my vote.

Service size is different things to different people for different reasons. As 'service size' is not defined in any way it is simply a slang term that has little real meaning.

Agree.

But generally a quick look at the main disconnect will be what we would consider the size of the service. As I think what the OP is trying to get.

 

[kwired]

Agree.

But generally a quick look at the main disconnect will be what we would consider the size of the service. As I think what the OP is trying to get.

So what do you have if there are multiple main disconnects and the common supply is less ampacity then the sum of the disconnects? Which is what OP has.

I have also seen single main 200 amp dwelling services with only 4 AWG aluminum service drop conductors supplying them - guessing POCO never expects to see 200 amps flowing on those services.

 

[electricalist]

Service size is the calculated 267 amps.

What the POCO calls it may be different - and likely will be in same classification as a full 400 amp service in most cases.

What the AHJ calls it for permit fees may also be different. This may very well be different in some AHJ's then others as well. Here there is a set permit fee for 0-100 amps, one for 101-200, one for 201-400, and I'd have to verify the higher figures, but it is in similar blocks of ampacity. So if done here, the OP's application would fall in the 201-400 and would be the same fee for any service value in the range.

Thats about what I came up with @256 . Obviously my math is off but still good practice

 

[Ponchik]

So what do you have if there are multiple main disconnects and the common supply is less ampacity then the sum of the disconnects? Which is what OP has.

I have also seen single main 200 amp dwelling services with only 4 AWG aluminum service drop conductors supplying them - guessing POCO never expects to see 200 amps flowing on those services.

From what I am picturing, the OP has a single meter 400Amp service.

If we had 6 disconnects with 6 separate meters then I would say the size of the service is based on the calculation, what the service conductors are and what the POCO says it is.

Usually here the POCO does not change their service drop on 200A upgrades. So a 200Amp upgrade has 2/0 copper service conductors the POCO service drop is #4 aluminum. However, the underground service conductors for 200Amp service is much bigger than #4 aluminum.

 

[kwired]

From what I am picturing, the OP has a single meter 400Amp service.

If we had 6 disconnects with 6 separate meters then I would say the size of the service is based on the calculation, what the service conductors are and what the POCO says it is.

Usually here the POCO does not change their service drop on 200A upgrades. So a 200Amp upgrade has 2/0 copper service conductors the POCO service drop is #4 aluminum. However, the underground service conductors for 200Amp service is much bigger than #4 aluminum.

You are right on with it depending on who is sizing it and why.

To NEC the OP has a calculated load of 267. If he were supplying a single overcurrent device he would need a conductor with at least 267 ampacity and next size up standard overcurrent device I believe is 300. POCO may see this as needing a 320 meter socket and therefore will call it 320 or even 400. Inspector will likely recognize it as at least 300 because that is the overcurrent device. NEC accepts more then one service disconnecting means to be supplied by a common feed sized to calculated load though. This doesn't mean the OP can have a load of 400 amps, even though 400 amps can be drawn without tripping any overcurrent devices, clear as mud right?

It still comes down to who is determining the size and what are they going by.

 

[FREEBALL]

I did same service but used 600 alum to service drop and 400 copper xhhw for lower due to LB capacity of 3 400 mcm came out less exp than a nec mogul and using 600 aluminum. Panels were grouped and used taps in trough to branch to 2 200 amp mains. It was a 320a service.

I apologize for grammar using phone to type puter still in shop

 

[electricalist]

I just saw in the 2011 that exception #3 to 230.90(A) allows the combined ratting of the handles where two to 6 breakers are used as the disconnects to exceed the rating of the service conductors, it was even in my 1999 NEC so I must have forgot all about this exception:ashamed1:

disregard my previous post


So with the above known I change my post to C. 400 amps

Is 230.90 excepion #3 correct? Or is the word service not mean service entrance. It seems confusing to me because I think you could ocprotect 6 things to be greater than the service conductors..

 

[Smart $]

Is 230.90 excepion #3 correct? Or is the word service not mean service entrance. It seems confusing to me because I think you could ocprotect 6 things to be greater than the service conductors..

Being correct vs. compliant is debatable... but it's been that way as long as I can remember.

 

[meternerd]

You are right on with it depending on who is sizing it and why.

To NEC the OP has a calculated load of 267. If he were supplying a single overcurrent device he would need a conductor with at least 267 ampacity and next size up standard overcurrent device I believe is 300. POCO may see this as needing a 320 meter socket and therefore will call it 320 or even 400. Inspector will likely recognize it as at least 300 because that is the overcurrent device. NEC accepts more then one service disconnecting means to be supplied by a common feed sized to calculated load though. This doesn't mean the OP can have a load of 400 amps, even though 400 amps can be drawn without tripping any overcurrent devices, clear as mud right?

It still comes down to who is determining the size and what are they going by.

As far as POCO's go, there is nothing between a 200A service and a 400A service. Meters are Class 100 (old school....don't think they're even available anymore), Class 200, and Class 320 (for 400A services) for self-contained. Anything over that gets CT's. Services are rated the same way...200A, 400A (320A meter) for self-contained, and CT's for anything bigger. All CT meters are now Class 20. Multi-meter services such as apartments are usually sized based on what the customer requests.

 

[kwired]

As far as POCO's go, there is nothing between a 200A service and a 400A service. Meters are Class 100 (old school....don't think they're even available anymore), Class 200, and Class 320 (for 400A services) for self-contained. Anything over that gets CT's. Services are rated the same way...200A, 400A (320A meter) for self-contained, and CT's for anything bigger. All CT meters are now Class 20. Multi-meter services such as apartments are usually sized based on what the customer requests.

Those are plug in meters, I have seen larger capacity bolt in meters a few times, but usually CT metering is desired if they won't allow a 320 to handle it.

 

[iwire]

Is 230.90 excepion #3 correct? Or is the word service not mean service entrance. It seems confusing to me because I think you could ocprotect 6 things to be greater than the service conductors..

Below is a poorly rendered one line drawing of a service I worked on. It is allowable under exception 3 and the only thing that really protects the service conductors and switchgear are the rules in the NEC that require future installers / designers to do load calculations to make sure any addtions do not overload the switchgear or the service conductors.

As a side note another reason this set up is desirable due to the fact it avoids having to provide GFP systems for 480 volt service. (No breakers 1,000 amps or over)

 

[electricalist]

Ty kwired I had asked about this type of set up in houses to others. When the panel is a mlo split bus. I often thought one day someone for whatever reason is going to think, I can change this panel to a 200 amp not realizing the 100 amp feeders could be corrupted if not done with a understanding of loads. Houses seem more likely at risk.

 

[meternerd]

Those are plug in meters, I have seen larger capacity bolt in meters a few times, but usually CT metering is desired if they won't allow a 320 to handle it.

Bolt in meters (K base meters) were the original 400A meters. Still rated 80% continuous. They have been replaced with the Class 320 Form 2S socket base meter. No non-CT meters exist that are over 400A, old or new. CT meters came with either hardwired bases (A base) or socket base (S base). Both are wired through a test switch. A base meters are no longer built. Some manufacturers have come out with Class 320 three phase meters, but many utilities (ours included) don't allow them.

 

[kwired]

Bolt in meters (K base meters) were the original 400A meters. Still rated 80% continuous. They have been replaced with the Class 320 Form 2S socket base meter. No non-CT meters exist that are over 400A, old or new. CT meters came with either hardwired bases (A base) or socket base (S base). Both are wired through a test switch. A base meters are no longer built. Some manufacturers have come out with Class 320 three phase meters, but many utilities (ours included) don't allow them.

I installed a bolt in (K base) maybe 8-10 years ago, have they been replaced or just the POCO you worked with stopped using them?

I do run into three phase 320 meters somewhat frequently, enough that I'd say they are not at all rare in this area.