Mike Dolt Enterprises
Mike Dolt Enterprises
User: guitarchris, Location: Central North Carolina
Asked on: Sunday, March 20, 2011 at 12:05 pm EDT
Answered on: Tuesday, May 14, 2024 at 3:02 am EDT
Question: Let me start this by stating that we do 98% resi work. Most of the commercial work we do is interior work or maintenance. That said we have been asked to do service upgrade on a restaurant. We are separating the existing service off of a trough that serves several other tenants in the same building. We want to leave all the other items alone, as it is as old as the hills and a mess. It is 3 phase coming in and 2 legs coming off of a 5 jaw meter to a 200A single phase panel that serves the restaurant. The A/C that are on the roof are tripping the main when all is on.I plan to build a 208/120 400A 3 phase service with a standard 3 ph meter base with a 18 circuit 3ph 200A panel beside the meter. Then a 3 phase 200A main breaker disconnect on the other. Can I just come off 2 legs of the 3 phase breaker/ disco to feed the 200A single phase panel inside the restaurant? If I can could I just come off two legs at the meter to feed a single phase disconnect to save on cost? How about the panel, can it be single phase, pulled off 2 phases? None of the equipment is 3 phase (including A/C's).I'm just looking for the simplest, cleanest, cost effective method for my install. If I was doing this on a single phase resi scenario I would use a meter panel combo for ease of install, I don't think such a thing exists for 3 ph. I don't live in the commercial world, so help a bother out!I'm
Meter and Panel Options
Meter Base with Panels
Yes, you can install a 3-phase meter base with separate 3-phase and single-phase panels. This is a common practice in commercial installations.
Single-Phase Meter with Disconnect
You
cannot come off two legs of the meter base to feed a single-phase disconnect. The meter must be rated for the full 3-phase load.
Single-Phase Panel
Feeding from 3-Phase Disconnect
Yes, you can feed a single-phase panel from two legs of a 3-phase disconnect. This is a common method for supplying single-phase loads in a commercial setting.
Pulling from 2 Phases
No, you
cannot pull a single-phase panel directly from two phases at the meter. The panel must be fed from a disconnect or panel rated for 3-phase service.
Cost-Effective Method
The most cost-effective method for this upgrade would be to:1. Install a 3-phase meter base with separate 3-phase and single-phase panels.
2. Feed the 3-phase panel with a 3-phase 200A main breaker disconnect.3. Feed the single-phase panel with a 2-pole 200A breaker from the 3-phase disconnect.
Additional Considerations: The new service will require a separate grounding electrode system. The existing AC units may need to be replaced or reconnected to the new service.* It is advisable to consult with a qualified electrician for the specific details and safety requirements of your commercial installation. Flag for review