Dual 200A Main Panel and Wire Layout

[Stuntman]

The original (simple) layout for this project got up-ended when discussing with the local power company. Now I am having to redo the layout of the meter/disconnects/panels/service wire. I would like appreciate some feedback of the plan as now I am unsure if there are better choices than what I have now:



Questions:
1. I already had some 4/0-4/0-2/0 URD for the original plan, but with the 200A running 60ft back to to the workshop (now a subpanel), I was curious if it was necessary/worth-it to upgrade to 250-250-250-3/0?
2. The two disconnects at the house are actually small exterior 8 space 200A Main Breaker panels with feedthrough lugs. This seemed as practical as a 200A shutoff and allows for things like condensing units or a generator to be hooked up at that location if needed. I do realize this causes the house and workshop main panels to be sub-panels and require a dedicated ground wire.
3. The two panels at the workshop may seem odd, but here is why I did that: I plan to run URD between the house and the workshop and figured I would want to transition to THHN or SER inside the structure anyway. Additionally, it is another 50 ft to get to the main breaker in the utility room (this panel will serve welders/motors/machinery etc) and the place where the URD physically enters the workshop is actually a reasonable place to put a panel and serve some moderate amperage loads (clothes dryer, 220V hydraulic pump, etc). I figured a main lug panel with feed-through would let me both transition the wire, and serve these loads. Reasonable?
4. I also used main lugs instead of breakers for both panels in the workshop as I figured having superfluous 200A main breakers at every drop was not optimal. Anyone care to comment if I should reconsider?

 

[infinity]

1) 250's might be overkill unless you know that your load will be approaching 200 amps and you're concerned about voltage drop.
3) You'll need a disconnecting means where the conductors enter the workshop also it would need to be on the outside if you're running unlisted URD.
4) Nothing wrong with a main breaker in the panel even if not required.

 

[kwired]

There needs to be a main disconnecting means on or inside near point of entry at the shop, or here is one place since 2020 NEC where you possibly could have main lug panel and up to six mains in that panel since it is not service conductors supplying it.

The ? after 350 kcmil from utility - they don't have to follow NEC. If the load just isn't there (which it seldom is for any lengthy duration with dwellings) they may run whatever size conductor they deem suitable for the load. 350 aluminum tends to be somewhat common on 320-400 amp services around here. I seen some that only have 4/0 aluminum as well though. Have also seen 350 aluminum on commercial applications that had 600 or 800 amp worth of service conductors on customer side of metering equipment. The transformer supplying things never had the 600-800 amp capacity either though.

 

[augie47]

You could use Exception 3 at 230.40 and feed the garage straight from the meter eliminating one disconnect at the house and simply run 3 conductors.
(as noted, you still need a disconnect at the garage)

 

[Little Bill]

The original (simple) layout for this project got up-ended when discussing with the local power company. Now I am having to redo the layout of the meter/disconnects/panels/service wire. I would like appreciate some feedback of the plan as now I am unsure if there are better choices than what I have now:

Do you have an electrician working for you on this?

 

[Stuntman]

This is excellent feedback. A few new notes/questions:

1) 250's might be overkill unless you know that your load will be approaching 200 amps and you're concerned about voltage drop.

Understood. This just ended up being a lot longer run after the meter to some relatively heavy loads (welders, motors, etc)

3) You'll need a disconnecting means where the conductors enter the workshop also it would need to be on the outside if you're running unlisted URD.

I'm glad you brought this up. Is there a direct bury cable (250-250-250) that can avoid a disconnect on the outside of the garage? If not, sounds like I need to burying 3" PVC instead of using direct bury?

4) Nothing wrong with a main breaker in the panel even if not required.

I was always under the impression extra main breakers had a small effect on voltage drop then led to the ambiguity of which breaker will trip in a fault condition. Is this not that much of an issue?

You could use Exception 3 at 230.40 and feed the garage straight from the meter eliminating one disconnect at the house and simply run 3 conductors.
(as noted, you still need a disconnect at the garage)

I originally though I could do this, but the disconnect was a stipulation from the power company that they want a disconnect before conductors go underground.

There needs to be a main disconnecting means on or inside near point of entry at the shop, or here is one place since 2020 NEC where you possibly could have main lug panel and up to six mains in that panel since it is not service conductors supplying it.

Understood. I have no problem putting in a disconnect there, just wanted to avoid a bunch of 200A breakers inline with each other.



Thanks for the feedback thus far.

 

[augie47]

stepping back to LittleBills question....(post #5)
do you have an electrician working with you on this ?

 

[infinity]

I'm glad you brought this up. Is there a direct bury cable (250-250-250) that can avoid a disconnect on the outside of the garage? If not, sounds like I need to burying 3" PVC instead of using direct bury?

It would need to be a listed type of cable from Article 310. Even if it's listed you will still need a disconnecting means for the separate structure either on the outside of the structure or immediately on the inside where the conductors enter the structure.

I was always under the impression extra main breakers had a small effect on voltage drop then led to the ambiguity of which breaker will trip in a fault condition. Is this not that much of an issue?

No issue with an additional main breaker.

 

[electrofelon]

I originally though I could do this, but the disconnect was a stipulation from the power company that they want a disconnect before conductors go underground.

I would fight them on this, I don't see what business it is of theirs what you do after the meter. Where is the service point? Not following that reasoning either: why are the underground conductors after the pole okay without a disconnect but the others aren't?

 

[Little Bill]

I am closing this thread until post #5 and post #7 are answered. OP can message one of the Mods with the answer and we can reopen it.