Calculated Res. Service comes at 603A

[Designer69]

My calculated load comes at 603A after all demand factors applied. Question is what standard service size to go with?

Not sure if I just specify 600A anyway, 700 (which doesn't seem so standard) or 800?


Thank You

 

[ramsy]

My calculated load comes at 603A after all demand factors applied. Question is what standard service size to go with? Not sure if I just specify 600A anyway, 700 (which doesn't seem so standard) or 800?

500A if it qualifies as a multifamily dwelling, per 310.15(B)(7) 2017 NEC adds 208Y/120v services as well.

 

[kwired]

Is it really large house or is there just a lot of load that other houses don't typically have? If it were 203 amps and was questioning in similar manner - I say definitely go with 400 amps of supply, it doesn't really cost that much more then 250 or 300 does. If you are going to increase beyond 600 then I'd also say probably go with at least 800, but won't necessarily tell you that you must do anything in particular without knowing more details either.



That said, unless there is lots of electric heat, or other high demand loads - reality is 600 is likely plenty though.

 

[ptonsparky]

My calculated load comes at 603A after all demand factors applied. Question is what standard service size to go with?

Not sure if I just specify 600A anyway, 700 (which doesn't seem so standard) or 800?


Thank You

I think you made a mistake in your calculations and it should be 597A.

 

[kwired]

If he can knock off just 2 amps 601 is a standard fuse size

 

[Designer69]

Thank you for the great responses. I should have mentioned this is a 3 phase service to a 16 unit apartment building.

There is not a lot of electric heat. There are washers/dryers and A/C condensing units for each dwelling.

I tried to tweak the numbers a bit and I can reasonably get it to 600.4A haha.

Per your answers, I am leaning a bit more on the 800A side because I don't want to cut it too close.


Thanks for the help.

Edit: Eaton makes a 700A AL Main terminal box/breaker combo. This could be a good option as well.

 

[beanland]

800A 208Y/120V

800A 208Y/120V

I would be inclined to agree with you, go for the 800A 208Y/120V service. I assume this will have 120/208V 3-wire services to each apartment? Use a meter cluster, one for each apartment and one for the house service. Another thing to consider, would it be reasonable to have two 400A service points? If the building is large enough (horizontal, not vertical) it might be a better design to take two service points on opposite ends of the complex.

 

[ramsy]

..Another thing to consider, would it be reasonable to have two 400A service points?..

If apartment complex had 2 separate buildings with its own service, then 310.15(B)(7) might be allowed within each 400A service.

 

[kwired]

If apartment complex had 2 separate buildings with its own service, then 310.15(B)(7) might be allowed within each 400A service.

that section only applies to conductors that supply an individual dwelling unit.

 

[Sierrasparky]

Either case you need a main switch.
Is this OH or UG.
Around this state 600a is usually the largest you can get for OH.
Other than the Main being 800a I don't think the rest of the equipment will be different from 800 or 600.

 

[petersonra]

My calculated load comes at 603A after all demand factors applied. Question is what standard service size to go with?

Not sure if I just specify 600A anyway, 700 (which doesn't seem so standard) or 800?


Thank You

do you really have a choice? unless there is a huge difference in price between 600 and 800 A services, I would just go for the 800 A service.

if there is a huge difference, you might want to see if you can find 4 Amps of load that is not really there. make sure you use the right voltage when you do your load calculations.

 

[Designer69]

Either case you need a main switch.
Is this OH or UG.
Around this state 600a is usually the largest you can get for OH.
Other than the Main being 800a I don't think the rest of the equipment will be different from 800 or 600.

It comes from OH then goes underground from a riser pole to a new xfmr. then UG to the new building.

So I guess it qualifies as UG.


Does the electrician usually coordinate the new service point/xfmr location etc. with the utility co. or is the engineer expected?


Thanks for all your help.

 

[kwired]

It comes from OH then goes underground from a riser pole to a new xfmr. then UG to the new building.

So I guess it qualifies as UG.


Does the electrician usually coordinate the new service point/xfmr location etc. with the utility co. or is the engineer expected?


Thanks for all your help.

If there is an engineer involved, that should be part of his job. Electrician may have to do some coordinating with some of the finer details though.

 

[Ragin Cajun]

3 amps???

Time to sharpen the pencil and redo the calculations. Been there, done that.

 

[ramsy]

that section only applies to conductors that supply an individual dwelling unit.

Dwelling, Multifamily. A building that contains three or more dwelling units. (CMP-1)

 

[ptonsparky]

I haven’t done any apartment housing of that size but I would think the loading would be consistent throughout its lifetime. 599 amp Service should be good. Future EV charging would be the changer.

 

[kwired]

Dwelling, Multifamily. A building that contains three or more dwelling units. (CMP-1)

You can cite that definition all you want but it doesn't change what it says in 310.15.(B)(7):

For one-family dwellings and the individual dwelling units of two-family and multifamily dwellings, service and feeder conductors supplied by a single-phase, 120/240-volt system shall be permitted be sized in accordance with 310.15(B)(7)(1) through (4).

Only applies to the supply conductors (feeder or service) to an individual dwelling unit.

 

[curt swartz]

You can cite that definition all you want but it doesn't change what it says in 310.15.(B)(7):




Only applies to the supply conductors (feeder or service) to an individual dwelling unit.

And in this case it can't be even be used for the individual dwellings since the supply voltage is 208/120.

 

[infinity]

A 16 unit building and you're trying to jump through hoops to find a way to eliminate 3 amps from your calculation? I would just go with 800 amps which leaves room for future expansion.

 

[Dennis Alwon]

If you go with 3- 200 amp panels and 1-100 amp panel it may save a tad bit but personally I would probably go with 4-200 amp panels. Alot cheaper than an 800 amp panel