House Load

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frofro19

Senior Member
Location
VA.
Occupation
Master Electrician
What size AL conductors would I need for a 200 amp 3 phase 120/208 service for a house load consisting of,
5 dryers
5 washers
1600 watt mini split HP
Water heater
That's all that would be on the panel.
According to my calculation with everything on at once, would be a demand of 108 amps.
Can I get by with 4/0 AL conductors for this service? This is in a multi-family dwelling.
 
Are you asking for the load calc to find the size of the service or are you stating you did the load calc and you will have a 200 amp service? You state thats all thats in the panel, so this is not the service?
 
Sounds like the house panel is supplying the laundry, which I don't think it qualifies as residential, but they certainly are large enough for the load.
 
mikeames said:
Are you asking for the load calc to find the size of the service or are you stating you did the load calc and you will have a 200 amp service? You state thats all thats in the panel, so this is not the service?
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I did the load calculation and it's around 108 amps and wondering if I can get by with 4/0 AL. I have a 3 phase 200 amp panel installed.
 
LarryFine said:
Sounds like the house panel is supplying the laundry, which I don't think it qualifies as residential, but they certainly are large enough for the load.
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We ended up putting in a separate service just for the laundry so it's a separate service just for the laundry. It's actually a different building but on the same property.
 
I honestly don't know how to view this. Normally the service conductors can be 83% of the rated service in which case your ok, since 4/0 AL is good for 180 amps at 75c and you only need 166A, but thats only when the service feeds the entire load. This does not. This has been debated many times before. I am not sure based on these circumstances.
 
mikeames said:
I honestly don't know how to view this. Normally the service conductors can be 83% of the rated service in which case your ok, since 4/0 AL is good for 180 amps at 75c and you only need 166A, but thats only when the service feeds the entire load. This does not. This has been debated many times before. I am not sure based on these circumstances.
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This particular service is feeding the entire load. It's a separate service to a separate building feeding the entire load. The only load in the building is the laundry and mini split system.
 
mikeames said:
I honestly don't know how to view this. Normally the service conductors can be 83% of the rated service in which case your ok, since 4/0 AL is good for 180 amps at 75c and you only need 166A, but thats only when the service feeds the entire load. This does not. This has been debated many times before. I am not sure based on these circumstances.
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Where does the 166 come from? OP said 108 amps, in which case 4/0 AL is plenty (1/0 would do it in fact).
 
mikeames said:
I honestly don't know how to view this. Normally the service conductors can be 83% of the rated service in which case your ok, since 4/0 AL is good for 180 amps at 75c and you only need 166A, but thats only when the service feeds the entire load. This does not. This has been debated many times before. I am not sure based on these circumstances.
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The 83 % rule is moot for this discussion as this is not a dwelling.
 
texie said:
The 83 % rule is moot for this discussion as this is not a dwelling.
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👍
The entire complex may be residential, but as this is a separate building it would not, IMHO, qualify.
Just as the detached garage of a residence could not take advantage of the 83% rule if the garage were fed by a separate set of service wires.
 
LarryFine said:
Sounds like the house panel is supplying the laundry, which I don't think it qualifies as residential, but they certainly are large enough for the load.
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I know the conductors are large enough but can they be on a 200 amp ocpd since that's a standard size in which panel boxes come in?
 
Eddie702 said:
a separate service for a separate building with mini split, washers, dryers and water heater, what about lighting and receptacle loads?
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It has one service receptacle and 6 LED wafer lights which is actually no load.
 
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