Feeding 2 panels from one source

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Bill Turax

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this is for a single family residential home. single phase, 120/240v.

upgrading service to 400 amp. Due to layout, panels can not be near meter location so we will need to install a disconnect next to the meter.

there will be (2) 200 amp panels. one panel in the basement and one panel on the top floor. typically this is not an issue. simply install (2) 200 amp disconnects next to the meter and take one 200 amp feeder to each panel from its own disconnect.

in this case however there is not enough room to install (2) separate disconnects. The only product i see that is narrow enough is a 400 amp breaker enclosure. the 400 amp breaker has 2 lugs per pole.

my question: Is it permissible to take 2 loads to sperate panels on different floors from the load side of one service disconnect breaker?
 
Bill Turax said:
my question: Is it permissible to take 2 loads to sperate panels on different floors from the load side of one service disconnect breaker?
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augie47 said:
Only if you can meet the 240.21 "tap rules".
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Reading over 240.21 especially (D) which seems to be the relevant section, I beleive what you want to do would be code compliant.

This appears to be no different than attaching two branch circuits to one 20 amp breaker in the panel (either at the breaker where allowed or joined after the breaker) which is done all the time.
 
You have a 400 amp OCPD but 200 amp feeders so the tap rules would apply.

Assuming you cant find a disconnect that will fit your space that has 2- 200a breakers / fused

1. Run the feeders outside the building as taps. The set a 200A disconnect outside where the feeders go into the house. Ugly and more cost but works.

2. Replace 200 amp panels with 400 amp panels and run a 400 amp feeder to each panel. Even more expensive but also works

3. Stick with 200 amp service and distribute as usual. Simple and most likely sufficient. What are the loads on the panels? Make them 100 amp main breaker panels.
 
mikeames said:
You have a 400 amp OCPD but 200 amp feeders so the tap rules would apply.

Assuming you cant find a disconnect that will fit your space that has 2- 200a breakers / fused

1. Run the feeders outside the building as taps. The set a 200A disconnect outside where the feeders go into the house. Ugly and more cost but works.

2. Replace 200 amp panels with 400 amp panels and run a 400 amp feeder to each panel. Even more expensive but also works

3. Stick with 200 amp service and distribute as usual. Simple and most likely sufficient. What are the loads on the panels? Make them 100 amp main breaker panels.
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I believe hen could have interior panels as long as the they were located where the cable enters the building.
b. Inside, nearest the point of entrance of the tap conductors
 
Coppersmith said:
Reading over 240.21 especially (D) which seems to be the relevant section, I beleive what you want to do would be code compliant.

This appears to be no different than attaching two branch circuits to one 20 amp breaker in the panel (either at the breaker where allowed or joined after the breaker) which is done all the time.
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These conductors are on the load side of the service disconnect and 240.21(D) does not apply.
The proposed installation would have to be installed in accordance with one of the provisions in 240.21(B), or as the previous posts suggests, install 400 amp conductors from the service disconnect to each of the panels.
 
the only way to take two feeders out of the load side of a 400a breaker is if both feeders are rated 400a, ie, 500MCM.
but you'd have to check if you can land 500mcm into the lugs of a 200a panel. another way is to bring the 500mcm into some location you can mount two 200A FSD's, then run 3/0 to each panel.
 
11Haze29 said:
the only way to take two feeders out of the load side of a 400a breaker is if both feeders are rated 400a, ie, 500MCM.
but you'd have to check if you can land 500mcm into the lugs of a 200a panel. another way is to bring the 500mcm into some location you can mount two 200A FSD's, then run 3/0 to each panel.
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You can use the rules in 240.21(B) to take 200 amp conductors out of the 400 amp breaker....of course there are distance limits that would probably not work for this installation, but full sized conductors are not the only option.
 
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