What's the NEC code section for main swbd load summary?

[fandi]

Hello All,
For a commercial plaza, if the plaza owner installs a new electrical service to feed the existing stores, is a main switchboard load summary required per NEC? If yes, what's the NEC code section for switchboard load summary? The engineer designing this project says no main swbd load summary is required because that's the tasks of individual stores, he only designs for the new main swbd for the plaza owner. He also says 220.87 methods of determining existing electrical loads is not applicable because the main service is new.
Thanks.

 

[Elect117]

If you are planning to refeed existing stores and their loads are known, you should be using it. Whether you use 220.87 or add up their devices. Apply demand factors as applicable in the other sections of 220. He is definitely wrong about his interpretations on how to calculate the load. I would double check he is licensed lol

You would be looking at sections 230.32(A) where it says to use the calculated load from art. 220. You can't size a service without knowing the loads.

The code is a minimum so if you are know each store has a 150A MCB for their feeder and you have 3 stores, you are okay to install a 600A service, with 600A worth of wire and refeed their 150A MCB. You would just put that each load is 150A.That is the lazy way.

Some customers don't care if you try to "reduce" their cost. They might already be sold on buying a 600A service upgrade. Sometimes the cost between installing a 600A service and a 400A service is minimal and the customer just wants more.

 

[jaggedben]

I think the engineer is being quite disingenuous arguing that the NEC does not require load calculations for existing stores. It may not be his task to do the load calculation for each store, but if not then it is his task to get someone to provide it to him. Any valid method in article 220 could be used. (For stores I think that's 220 Part III or 220.87, but read 220.)

If the stores weren't existing and the design were based on something like 'the contract provides for each commercial space to be provided with x amount of VA to be used appropriately by the tenant' then I could see his argument flying. But not when there is an existing basis for determining the load.

 

[fandi]

If you are planning to refeed existing stores and their loads are known, you should be using it. Whether you use 220.87 or add up their devices. Apply demand factors as applicable in the other sections of 220. He is definitely wrong about his interpretations on how to calculate the load. I would double check he is licensed lol

You would be looking at sections 230.32(A) where it says to use the calculated load from art. 220. You can't size a service without knowing the loads.

The code is a minimum so if you are know each store has a 150A MCB for their feeder and you have 3 stores, you are okay to install a 600A service, with 600A worth of wire and refeed their 150A MCB. You would just put that each load is 150A.That is the lazy way.

Some customers don't care if you try to "reduce" their cost. They might already be sold on buying a 600A service upgrade. Sometimes the cost between installing a 600A service and a 400A service is minimal and the customer just wants more.

Thank you. I don't see section 230.32(A) in 2020 NEC/2022 CEC so perhaps you could guide me to another code section that requires the main service to accommodate the electrical loads to avoid being overloaded. I believe it's 220.40.

 

[Elect117]

Thank you. I don't see section 230.32(A) in 2020 NEC/2022 CEC so perhaps you could guide me to another code section that requires the main service to accommodate the electrical loads to avoid being overloaded. I believe it's 220.40.

Oops. 230.42(A)

 

[jaggedben]

Looking at this again, I might say that if all the feeders to the stores are being replaced with 'like for like' for the existing, then maybe it's okay. But I think the engineer has to provide some basis or other for the design choices, he can't just say "I don't have to know."

 

[electrofelon]

? The engineer designing this project says no main swbd load summary is required because that's the tasks of individual stores, he only designs for the new main swbd for the plaza owner.

So how is he sizing the thing? If this is a replacement of existing equipment, it might not be unreasonable to just go with whatever size the old one was - obviously you have to make a few assumptions doing that but if they have not had any problems.... Is that the approach he is taking?

 

[fandi]

So how is he sizing the thing? If this is a replacement of existing equipment, it might not be unreasonable to just go with whatever size the old one was - obviously you have to make a few assumptions doing that but if they have not had any problems.... Is that the approach he is taking?

He says it's a service upgrade but he doesn't say how many amp is the existing service.