How to connect two 200 amp panels and 200 amps of solar to a single 320/400 meter socket

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Scheffler Energy

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Minnesota USA
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Master Electrician
Hello,
I am trying to figure out the best solution to a customers problem. We want to mount 3 services on a wood backer board. I want to mount 1 meter 320 millbank meter and triple lug out of the load side to a solar service , 200 amp service for a future shed and 200 amp service panel at the backer board. So I would have two 200 amp disconnects and one 200 amp panel at the backer board. My problem is that mill bank doesn’t UL any of the meters to be triple lug even when they make a triple lug ! I need to figure out a utility / UL / AHJ compliance to have 3 services on one meter or I could do two meters maybe I could mount a tap box with lugs before the service panel on the board and go from there to the solar disconnect and from the tap box to the 200 amp panel on the backer board. Milbank will only allow a double lug on the load side of there meter. Any suggestions or strategies is much appreciated ! 2023 NEC Minnesota
 
Hello Larry I don’t think utilities like Polaris lugs for service taps which is silly because they do it there self’s in the ground tap boxes ! I think I answered my own question I think a double lug in the meter with a tap box for the solar and the 200 amp panel will be the best solution ! Thank to for responding ! I still have a lot to learn
 
I have a question about a 200aml terminal box rated for service if I was to tap 200 amps of solar into this box and a 200 amp panel the rating of the tap box is only requires to be 200 amps ? Others I spoken to want to see 400 amp tap box because the possibly of over two hundred amps on the lugs ? I don’t think this is correct because from my understanding the 200 amps of solar would be subtractive and would not be additive to the 200 amp panel draw. Any advice on this Scenario ?
 
Scheffler Energy said:
I have a question about a 200aml terminal box rated for service if I was to tap 200 amps of solar into this box and a 200 amp panel the rating of the tap box is only requires to be 200 amps ? Others I spoken to want to see 400 amp tap box because the possibly of over two hundred amps on the lugs ? I don’t think this is correct because from my understanding the 200 amps of solar would be subtractive and would not be additive to the 200 amp panel draw. Any advice on this Scenario ?
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You are correct. See 705.11. Good luck educating others.
 
Personally I would have no trouble (and do) put 3 terminals on a 320 socket. The ones I get do not come with lugs, just studs. Technically, milbank does have a list of lugs, but I do view it as just a recommendation, they only list like two or three options it's kind of ridiculous, and most/all aren't even available in my area. Typically i use compression lugs back to back.

A note on terminology, this would be one service with three sets of service entrance conductors. Take a look at 230.40 exception # three also which may be handy in your situation.
 
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