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

    Default 3 Phase Electrical

    I did a quick walk through of a commercial building that someone may or may not want inspected just to get an idea of what is there and it's layout. I included a picture of where the 3 phase electrical enters the building (through the roof). I am not real familiar with 3 phase. Can someone tell me a little bit about what these devices are and there function that the conductors are installed through? I believe the double up the conductors for like a 400 amp service as opposed to using a larger gauge conductor explaining why there are 8 total conductors rather than four.

    The panel shown in the image is between the main service panel (exterior) and the breaker distribution panels (interior).




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  2. #2
    James Duffin's Avatar
    James Duffin Guest

    Default Re: 3 Phase Electrical

    It looks like an unused CT cabinet that was once used to meter the power used in the building. I say unused because I don't believe there are any signal wires leaving the current transformers.


  3. #3
    Join Date
    Feb 2008
    Location
    Iowa City, IA
    Posts
    97

    Default Re: 3 Phase Electrical

    I bet your right. Would that have been common in the 60's? Thanks!


  4. #4
    James Duffin's Avatar
    James Duffin Guest

    Default Re: 3 Phase Electrical

    It is still a legitimate method to meter three-phase power.


  5. #5
    Lou Romano's Avatar
    Lou Romano Guest

    Default Re: 3 Phase Electrical

    It is still a legitimate method to meter single phase power as well on commercial properties utilizing single phase power.


  6. #6
    James Duffin's Avatar
    James Duffin Guest

    Default Re: 3 Phase Electrical

    With single phase you can go up to 400 amp without using CT's but we were talking 3-phase so I focused on that in this discussion.


  7. #7
    Join Date
    Feb 2008
    Location
    Iowa City, IA
    Posts
    97

    Default Re: 3 Phase Electrical

    There is a regular electric meter on the exterior main service panel... my guess would be it was discontinued or changed with an addition to the building or upgrade of the service...


  8. #8
    Join Date
    Oct 2009
    Location
    michigan
    Posts
    421

    Default Re: 3 Phase Electrical

    May have been used for monitoring: for load shedding, for a particular time/watts reading, for an inter-phase device that would shut down motor(s) if and when it detected single-phasing i.e. loss of a phase, for recording of phase balance. I doubt it was ever utilized to meter by/for a utility co.
    May have been to decipher who, if two different occupants/suites, was using what power from a single metered service.


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