200A service split for house and shop

[JD_Oklahoma]

I'm looking for some advice from someone who may have a similar panel configuration or installed service like this before.

I recently had our service upgraded to 200A by my provider. I was told they would install a new meter panel with slots for up to three breakers. This was after I explained my intention of splitting the service with 100A to the house and 100A to the shop.

What I got was a 200A meter panel with one new 200A breaker which I paid them $150 for. I was not available to check the install so I did not discover this until after the crew was done and gone for the day.

After several discussions with the provider (asking if they could swap out the meter panel with the configuration I was looking for) I was told "whatever is past the meter is your responsibility" Ok, I'll have to make this work somehow.

I've had three electricians on-site and they have given me different options ranging from installing a new sub-panel on the back of the pole with two, 100A breakers or installing a new sub-panel on the back of the house with a 100A breaker for the shop.

This is the current setup in the two buildings:

Main panel in the house has two 90A breakers feeding out to the shop with direct burial. All conductors are 4 ga. aluminum (120V / 120V / Neutral) Ground rod installed near the shop panel. I know that's not up to code as one electrician looked at it said, "that's how they used to do it." Maybe back in the late 70s and early 80s I guess? The shop has an old GTE / Sylvania panel with Zinsco, Z-style breakers. That's going away to be replaced with a new panel with this project.


View from shop up to the house:

Overhead feed to from meter to the house panel and conduit feed to underground out to the shop

In my last call with the electric provider they recommended I call the electricians back out again because I do not need a sub-panel on the pole; they could just use the two open lugs coming off the 200A breaker:

New 200A meter panel

That's where the confusion and my question comes in. Do I really need to have a sub-panel on the pole to split out the service? The new panel in the shop will have a 100A main breaker on it. I have a quote for close to $4,000 to have everything installed:

• New subpanel on the pole with the overhead lines for the house re-routed over to it
• Two 100A breakers (one for house, one for the shop)
• Underground metal conduit from new subpanel out to the shop with new wire
• New panel installed in the shop

 

[Cmreschke]

First thought is metal conduit underground is kinda pricey. You could use pvc or direct burial to save some coin.

 

[tommied]

You are correct. Just use the disconnect to hook wire to shop and house. You do not need a subpanel. That is legal here in Arkansas. I actually just stuck 2 150 amp breakers under my breaker because I have 3 phase to my shop. Before I had single phase and used a box just like yours with the 250 breaker feeding the inhouse 100 amp boses. Hope this helps.

 

[Pwrgeek]

You can just tap 100A wire (#3 Cu or #1 Al) into the two available ports of the blocks (assuming that middle hole will take wire that large if not you'll need to add some L blocks). The caveat is that the services must be in conduit and must go immediately to the panels on entering the structures and cannot run for any distance inside the house or shop. If they run for any distance inside the rules get very complicated and you'll need to study 240.21(B) carefully to figure out what to do.


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[JD_Oklahoma]

Thank you all for the replies.

I'm looking at metal conduit because we have septic lines all across the yard and I hopefully would not hit any by using metal conduit buried down to 6"

For PVC I'd have to go down to 18"+ inches and would surely get into those lines.

Also, we have a ton of gophers which I believe damaged the original direct burial wiring. When I lost one side of the 120V coming into the shop I shut it off, dug up the line to inspect, and found one section whittled down to a sharp point. I figured I would have found a gopher skeleton right at that spot but I did not! lol

I could have just been a break in the wire jacketing that corroded down over time.

 

[Pwrgeek]

With only 6" of cover you would have to do dyed concrete backfill here. YMMV based on your particular AHJ.


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[wyliesdiesels]

eekkk #4 aluminum is too small for 90.

As Pwrgeek pointed out, u can use the rules of 240.21(b)(5) and connect #1 al or #3 cu between the shop and meter panel.

Yes u will need a 4-wire feeder 1-1-1-6 or 3-3-3-8. U will also need 2 grounding electrodes and make sure neutral bar is isolated.

3-wire feeders are no longer allowed as of 2008 code cycle...

6" Will work for IMC or RMC IF u wont be driving on it.

U will need 18" if u will be driving on it.

http://www.xwalk.com/images/Table_300.5-Min_Cover_Reqts.pdf

 

[Cmreschke]

With only 6" of cover you would have to do dyed concrete backfill here. YMMV based on your particular AHJ.


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Even in rigid?

 

[Pwrgeek]

Yep. In anything less than 18" of backfill you have to have at least 3" of red concrete cover. It's to warn someone they are about to get into something in a way where they really have to try to be stupid to keep going.


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[Cmreschke]

Interesting.