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  1. #1
    Join Date
    Feb 2008
    Location
    Iowa City, IA
    Posts
    97

    Default Single Phase Panel in 3 Phase building

    Can a single phase panel be used on a 3 phase electrical system if only a single leg to nuetral (120v) or two legs (208v) are going to be used (208Y/120 service)? Or do the manufacture specs need to be for a 3 phase electrical panel? I would assume using a single phase panel for the situation noated above would be ok, but just wanted to get additional opinions.

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    Last edited by Andrew Kolar; 03-10-2011 at 03:20 PM.
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  2. #2
    Join Date
    Mar 2007
    Location
    Charlotte NC Licensed in NC and SC
    Posts
    597

    Default Re: Single Phase Panel in 3 Phase building

    Yes, very common, assuming everything is done correctly like seperate ground/neutral busses in the 120/208 panels.

    Bruce King, B.A. King Home Inspections, LLC
    www.BAKingHomeInspections.com
    Certified Master Inspector, Independent Inspectorwww.IndependentInspectors.org

  3. #3
    John Steinke's Avatar
    John Steinke Guest

    Default Re: Single Phase Panel in 3 Phase building

    OK? Done all the time? I'm not so sure about that one ...

    Look to the fine printon the inside of the panel door to ascertain just what 'flavors' of electricity the panel is approved for. Then measure the service and figure out exactly what types of power are really available.

    I expect these fine points are beyond HI's in general, and even many electricians.

    Here's the short version: feeding a single phase panel from a 'delta' fed three phase panel is about the only way to get proper single phase out of that service. Split-buss panels were once common in this use, but that solution seems to have waned in popularity.

    If you service is a 'wye' fed three phase, there's no need for a single phase panel. Indeed, such smells of bad practice and power quality issues- though I'm not certain it would be a code violation.

    If you do have a 'wye' service and a single phase panel, then I suspect there was some work done by unqualified folks- so keep digging. They're sure to have committed worse sins.


  4. #4
    Norm Grande's Avatar
    Norm Grande Guest

    Default Re: Single Phase Panel in 3 Phase building

    As an electrician, this is a common scenario, for example in a townhouse or sometimes commercial aspect. We seldom used 3 phase in the units unless specifically spec'ed, which would be pricey. In a commercial setting we would use 3 phase for the rooftops, and single phase panels for lighting in the small shops.
    If they were individually metered, we would often use 3 phase just because of the rooftop unit. Of course if there was a larger shop that wanted 3 phase compressors or equipment, no question...3 phase. By the way, we would spec 208 volt electric baseboard heaters, otherwise your heat output drops off considerably. I forget the percentage, its been a while since I was contracting on my own.
    Norm


  5. #5
    James Duffin's Avatar
    James Duffin Guest

    Default Re: Single Phase Panel in 3 Phase building

    I think the concern is that it is hard if not impossible to find a single phase panel rated at 120/208 volts so the "professional" thing to do is to install a 120/208 volt three phase panel.


  6. #6
    Join Date
    Dec 2007
    Location
    Chico,Ca
    Posts
    423

    Default Re: Single Phase Panel in 3 Phase building

    Quote Originally Posted by James Duffin View Post
    I think the concern is that it is hard if not impossible to find a single phase panel rated at 120/208 volts so the "professional" thing to do is to install a 120/208 volt three phase panel.

    There are no issues w/ a 120/240V panel on 208/120V.


  7. #7
    James Duffin's Avatar
    James Duffin Guest

    Default Re: Single Phase Panel in 3 Phase building

    Quote Originally Posted by Rollie Meyers View Post
    There are no issues w/ a 120/240V panel on 208/120V.
    I agree.


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