3 phase service - Need Help

[inspector 102]

Existing 600 amp service fed from pad mount transformer through 4" conduits into existing building to 600 MDP. Utility company wants a second meter installed to break out lighting loads for different tariff on billing. Contractor want to pull #2 conductor in with the existing conductors, through the 600 MDP, then out the building to a CT cabinet, then back into the building to a new 100 Amp Lighting panelboard. Sounds like there might be some code issues with coming into the building with service entrance conductors then going outside to metering, then back in. Also concerned about both sets of service entrance conductors in same conduit. Where should I be looking for specifics on this situation?

 

[augie47]

Existing 600 amp service fed from pad mount transformer through 4" conduits into existing building to 600 MDP. Utility company wants a second meter installed to break out lighting loads for different tariff on billing. Contractor want to pull #2 conductor in with the existing conductors, through the 600 MDP,

With 1/0 conductors this would seem to meet NEC 230.2 as "one service. With #2s , it might be considered 2 service to 1 building.

Then out the building to a CT cabinet, then back into the building to a new 100 Amp Lighting panelboard. Sounds like there might be some code issues with coming into the building with service entrance conductors then going outside to metering, then back in.

Routing might be an issue. I would check 230.7 and 230.70(A)(1)

Also concerned about both sets of service entrance conductors in same conduit. Where should I be looking for specifics on this situation

With added conductors, derating might be an issue.

 

[cycotcskir]

Contractor want to pull #2 conductor in with the existing conductors, through the 600 MDP, then out the building to a CT cabinet, then back into the building to a new 100 Amp Lighting panelboard.

The "through the 600MDP" is throwing me. Are you meaning From the MDP?

Sounds like they are using the MDP to feed a sub-panel, but first going through a CT cabinet. Is that right?

 

[inspector 102]

cyco - No I mean through the MDP. They wish to puul the second set of conductors for the pad mount through the 600 Amp enclosure then back outside on the wall to a CT meter, then back inside to a panelboard. The reason is the concrete between the XFRM and the building would have to be torn up and trenched, and there is not much room. That is why I am questioning the install for compliance. Is there anything in the code that really prohibits the service entrance from entering the building, exiting for metering purposes, then coming back in for panelboard location. I realize Main Disconnecting becomes an issue, "immediately upon entering the building" and maybe that is where it starts to get uncomfortable to me. Looking for opinions at this point for code complaince. Thanks

 

[cycotcskir]

I think augie summed it up pretty well, especially 230.70 and derating. My brain is fried and I can't even think straight right now. Replying here is definitely requiring way too much brain power. doesn't sound like a good idea to me.

 

[ronmath]

I guess I'm confused why new conductors need to be pulled to the transformer at all. The lighting as I understand it is not an additional load but just want's to be metered seperately? Tap off before the existing ct/meter and run to new ct/meter then back to new main switch in same vicinity of existing main 230.33. This should put the meters and the mains together where they belong. The service conductors need to be sized for the loads, 230.31 (A), 230.42(A), not the disconnect sizes except as addressed in 230.42(B). When adding conductors to the service they should be parallel and of the same size and configurations and should be spliced together before any mains or you have more than one service. IMHO. Unfortunately that's all I have time to get into right now, but you are correct to question this proposed installation.