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Andrew Kolar
03-02-2011, 09:07 AM
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).


http://i303.photobucket.com/albums/nn125/KolarPhotos/A110301060_800x600.jpg
James Duffin
03-02-2011, 01:07 PM
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.
Andrew Kolar
03-02-2011, 07:33 PM
I bet your right. Would that have been common in the 60's? Thanks!
James Duffin
03-02-2011, 07:39 PM
It is still a legitimate method to meter three-phase power.
Lou Romano
03-04-2011, 07:11 AM
It is still a legitimate method to meter single phase power as well on commercial properties utilizing single phase power.
James Duffin
03-04-2011, 07:38 AM
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.
Andrew Kolar
03-04-2011, 07:41 AM
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...
bob smit
03-05-2011, 08:39 PM
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.