Underground pvc conduit in chicago

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Jimmy4645

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Hello, wondering if anyone can help me out?

I'm working on a restaurant build-out and there are two existing sets of 3" conduits already installed underground and stubbed into the tenant space. The stubs are steel, but I?m wondering if the conduit under the slab is PVC or steel? Because I want to use the conduit as my ground, but might get screwed if they installed PVC underground and I show no ground wire....

I have an 800 Amp service. Worst case scenario, I?m trying to feed 2 sets of 4#500 and 1#1/0G into two existing 3" conduits. Will this work?
 

iwire

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Staff member
Location
Massachusetts
Do the load calcs and determine the minimum neutral size needed, you may be able to reduce the neutral to a restaurant by quite a bit leaving more room for the EGCs.
 

iwire

Moderator
Staff member
Location
Massachusetts
Is 4#500kcmil and 1#1/0G in a 3" PVC even legal?

The 1/0 puts you over

That is why I am suggesting you could do three 500s, one .. say 4/0 ... and a 1/0.

I imagine this restaurant has a lot of line to line to line loads which mean you can drop the neutral size down if you do the calculations to prove it.
 

Jimmy4645

Member
Is this a service as in no separate EGC needed?

2 sets of 3 inch conduits fed underground to a C/T & M.F. within the switchboard room and 2 sets of 3 inch conduits fed underground into the tenant space. This is a feeder and not a service.

The issue is that the 2 sets of 3 inches conduits is set up for a 600 amp service and i would be comfortable with a 800. I have calculated a demand load of 549 amps
 
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