Modifying Existing Meter Center

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designer82

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An existing mixed-use (retail/residential) building will have one of the retail spaces converted to laundromat which will use a lot more amps than existing service/metercenter have.

The residential/house side won't have any change.

My question is whether just the existing 400A switch can be upgraded and the meter stacks (residential/house side) not touched. Although I'm thinking just putting in a new switch won't be compatible w/ the existing meter stack.

How would you do it?

Picture of equipment here:
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I would not remove the 400A switch. If you can get the 1000A service drop to within 25' of the 400A switch, just back-feed it with a 400A tap on the load side of the 1000A. Or run the 1000A service drop to a tap box (no 1000A main) and feed the 600A and 400A from there. Label each as "Main".

Can't tell from the picture, but it's not likely that meter center has 1000A horizontal busbars.
 
I would agree. You likely need the 400 amp switch to protect the meter center.
 
JoeStillman said:
I would not remove the 400A switch. If you can get the 1000A service drop to within 25' of the 400A switch, just back-feed it with a 400A tap on the load side of the 1000A. Or run the 1000A service drop to a tap box (no 1000A main) and feed the 600A and 400A from there. Label each as "Main".

Can't tell from the picture, but it's not likely that meter center has 1000A horizontal busbars.
Click to expand...
This is a great idea. Would you agree with how I have it drawn?

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What about grounding considering that 400A existing switch has the main ground.
Would you ground the tap box and remove ground from 400A existing switch?
Or ground the new 600A switch and keep ground as is on the 400A switch?

Thanks!
 
Ground all 3 (400A, 600A & Tap Box) by connection to the neutral
(Service disconnects &service enclosure)
 
designer82 said:
This is a great idea. Would you agree with how I have it drawn?

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What about grounding considering that 400A existing switch has the main ground.
Would you ground the tap box and remove ground from 400A existing switch?
Or ground the new 600A switch and keep ground as is on the 400A switch?

Thanks!
Click to expand...
What he said...
Ground all 3 (400A, 600A & Tap Box) by connection to the neutral
(Service disconnects &service enclosure)
Click to expand...
 
JoeStillman said:
I would not remove the 400A switch. If you can get the 1000A service drop to within 25' of the 400A switch, just back-feed it with a 400A tap on the load side of the 1000A. Or run the 1000A service drop to a tap box (no 1000A main) and feed the 600A and 400A from there. Label each as "Main".

Can't tell from the picture, but it's not likely that meter center has 1000A horizontal busbars.
Click to expand...
"to within 25' of the 400A"

Is that due to the 25' tap rule maximum?
 
So if the GEC connection is currently made at the existing 400A switch, then it can remain there right?
If I understand Sec. 250.24(A)(1) then it's fine there or at any other accessible point downstream of overhead service.

Do I have the grounding connections made correctly in the sketch below?



Thank you and happy holidays!
 
IMO, it would simplify things to simply bring all you GECs from the tap box and base the size on the service conductors to the tapbox.
 
augie47 said:
IMO, it would simplify things to simply bring all you GECs from the tap box and base the size on the service conductors to the tapbox.
Click to expand...

Ok, in that case would the electrician remove the existing GEC from the 400A switch and make all new ground electrode connections from the Tap box or keep the GEC/ground electrode system at the 400A switch as is?
 
designer82 said:
Ok, in that case would the electrician remove the existing GEC from the 400A switch and make all new ground electrode connections from the Tap box or keep the GEC/ground electrode system at the 400A switch as is?
Click to expand...
Either
 
Eddie702 said:
With something that size I would ask the POCO about 3 phase.
Click to expand...

Any problems with that existing 1 phase meter center by changing service to 3 phase?

I'm thinking the heating units in the apts. will output less heat.
Maybe issues with any other existing 240V loads changing to 208V?

Thanks!
 
designer82 said:
"to within 25' of the 400A"

Is that due to the 25' tap rule maximum?
Click to expand...
There is no "tap rules" for service conductors.

3 phase was mentioned, depending on how much actual load has been POCO possibly won't want to supply the increased load as a single phase service so that needs checked into as well.

Another option is leave what is there and add a second service disconnect to supply the new load. You are allowed up to six per allowed service. If the second one would happen to be three phase then technically you would have two services which is permitted if they are different characteristics and can be up to six disconnects for each.
 
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