Developing a Load Letter But There's More Than 1 Meter and Main Feeding a Apartment

[Tainted]

A client wants to add an electric dryer in his apartment. For feasibility in doing so, we would need to do a load letter. The apartment is being fed by 2 different panels from 2 different meters. Both main circuit breakers are 2 pole 50A supplied by 120/208V split phase.

My question is:
If I do a load letter, it would tell me the minimum amps required and that would be easy to do if it was a single meter and single main circuit breaker feeding the apartment. Article 220 lets you know the minimum requirements for a single main circuit breaker, not 2 main circuit breakers. Since it's 2 meters and 2 main circuit breakers feeding the apartment, how would I be able to do a proper load letter and determine if the electric dryer is ok for them to install? The facility has a dryer and laundry place but they want to install it in the apartment anyway.

 

[tom baker]

You would have to do a load calc for the apartment and then show which loads are from the different service, to determine which service has the capacity for a dryer.
2 meters for one unit? Over time that would be expensive for the flat rate charge for the second meter.

 

[Tainted]

You would have to do a load calc for the apartment and then show which loads are from the different service, to determine which service has the capacity for a dryer.
2 meters for one unit? Over time that would be expensive for the flat rate charge for the second meter.

Yea but what about the 3VA/sqft, if there are two mains feeding the apartment, which one of them would account for the total VA/sqft? Do both of them need to be calculated with the same total VA/sqft?

 

[suemarkp]

Calculate how many general lighting circuits you need for 3VA/sqft. Compare that number to how many general lighting breakers are in each panel and apportion the sqft accordingly. You could have it all in one or the other or partial or evenly split.

 

[Fred B]

Your opening statement regarding the apartment is confusing. You refer to "the facility" also apartment, also 2 meters to one apartment? Is this a larger apt complex, or a simple 2 or 3 family? Generally 2 meters to one unit would not be allowed, and a violation of 220.84(A)(1) in a multifamily building.
Normally 220.83 addresses many of your questions but if your statement that this one apartment has 2 services (generally a violation) then you need eyes on site to determine the proper apportionment between the 2 panels. You would as others suggested already need to find total loads for apt, then apportion that based on the distribution from each panel. This I don't see a simple calculation only from an office desk for apportionment. Also I believe you loose some of the "give" or "allowance" in loading calculation allowed by load diversity because of the 2 service distribution of the individual loads. (80% rule, demand loads)
You also have another issue that is not going to be an easy remedy, a 50 amp main panel is very likely fully loaded as to breaker spaces, and to add a double pole 30 not likely, also such a panel (50 amp main) is likely very old and getting a breaker unlikely. Very likely a service upgrade would be needed.

 

[Tainted]

Your opening statement regarding the apartment is confusing. You refer to "the facility" also apartment, also 2 meters to one apartment? Is this a larger apt complex, or a simple 2 or 3 family? Generally 2 meters to one unit would not be allowed, and a violation of 220.84(A)(1) in a multifamily building.
Normally 220.83 addresses many of your questions but if your statement that this one apartment has 2 services (generally a violation) then you need eyes on site to determine the proper apportionment between the 2 panels. You would as others suggested already need to find total loads for apt, then apportion that based on the distribution from each panel. This I don't see a simple calculation only from an office desk for apportionment. Also I believe you loose some of the "give" or "allowance" in loading calculation allowed by load diversity because of the 2 service distribution of the individual loads. (80% rule, demand loads)
You also have another issue that is not going to be an easy remedy, a 50 amp main panel is very likely fully loaded as to breaker spaces, and to add a double pole 30 not likely, also such a panel (50 amp main) is likely very old and getting a breaker unlikely. Very likely a service upgrade would be needed.

My apology for making it sound confusing, yes there is 2 meters in 1 unit. Reason for this is 2 apartments where combined to become 1, leaving it with 2 meters and 2 main breakers. I think they could get away with a 120V dryer by putting it on a panel that used to have kitchen loads but the old kitchen was removed. Since the apartments are combined there is only 1 kitchen now meaning all the kitchen loads are in 1 panel instead of 2 panels.