Interconnection Point advice

WallyWally Registered Users Posts: 11
I live on a rural acreage and am in the initial planning stage for a PV system
and would like a review of my planned interconnection point with the Utility.

My Utility feed comes in underground and up into a meter base/enclosure
on the outside of a detached garage.

From there it goes thru a short 6 inch long horizontal conduit to a Siemens
#WB2225 Outdoor Circuit Breaker Enclosure that has a 225 Amp max Rating.
The breaker installed in this enclosure is a 200 Amp two pole breaker.
From here the feed goes thru another short 6 inch long conduit to a Midwest T1220 Terminal Box.

This box has 3 big lugs, each with 3 large holes for wires sized 1/0 AWG to 250 Kcmil
and 3 smaller holes sized for 12 to 1/0 AWG.
Each of the lugs have 1 large and 1 small hole still empty.

The rest of the holes have wires that continue underground to the main circuit breaker panel
in the basement of the house about 150 feet away and also to another detached building.
The PV / Inverter system I am planning, has the Inverter outputting a max of 10KW AC
(about 42 Amps) and will be located about 75 feet from this Terminal Box.

This feed will have three #4 AWG THHN wires plus a ground wire in a conduit to a sub panel
with a back feed 50 Amp breaker and then to a lockable AC Disconnect switch and then thru
a short 6 inch conduit connecting to the Terminal Box lugs via the 3 smaller empty holes sized (12 to 1/0 AWG).

The sub panel feed and AC Disconnect switch will be on a panel about 6 feet from the Meter.

Any obvious code problems with doing it this way?

Comments

  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Interconnection Point advice
    Wally wrote: »
    I live on a rural acreage and am in the initial planning stage for a PV system
    and would like a review of my planned interconnection point with the Utility.

    My Utility feed comes in underground and up into a meter base/enclosure
    on the outside of a detached garage.

    From there it goes thru a short 6 inch long horizontal conduit to a Siemens
    #WB2225 Outdoor Circuit Breaker Enclosure that has a 225 Amp max Rating.
    The breaker installed in this enclosure is a 200 Amp two pole breaker.
    Any obvious code problems with doing it this way?
    You are fortunate that the enclosure (and therefore the buss bars) have a 225 Amp rating, since that means that you are allowed to back feed up to (225 x 1.20) - 200 = 75 amps. You would just miss code compliance with (200 x 1.20) - 200 = 40 amps and a 50 amp backfeed breaker.
    I have not looked at any of the rest.
    SMA SB 3000, old BP panels.
Sign In or Register to comment.