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#51255 - 04/26/05 07:27 PM Service or Sub Feeds
Sparky_1 Offline
Member

Registered: 11/20/04
Posts: 14
I have not thoroughly looked at this job, I'm going by what the maintains man has told me, I plan on looking at it
tomorrow. 1600 Amp service, four runs of 750? Aluminum, over the 30 years one run has lost a conductor ( shorted out against the
metal conduit). This is a 200'+ run. They are going to increase a 200 HP motor to a 300 HP so they want the service conductors fixed.
So it looked like a matter of trying to pull out the old conductors and replacing with new 750 AL.
My question is the concern if this is a service or a sub feed to the 1600 AMP MDP. A few years back they put in a generator that would
supply the entire location, a feed mill, a elevator and fertilizer building. So are these sub feeds going out from the transfer switch or are they still each independent services?? 750 MCM AL = 385 * 4 = 1540 or 900 MCM AL = 425 * 4 = 1700 Amps

Can four copper conductors be used in one run and keep the existing runs of Aluminum?
If it's possible it probable wouldn't happen anyways, copper costing 2 3/4 times more than Aluminum.

Thanks,

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#51256 - 04/27/05 05:15 AM Re: Service or Sub Feeds
Yoopersup Offline
Member

Registered: 03/04/03
Posts: 826
Loc: Michigan
Question Does Generator have main Breaker??
Question Does The power company feed the transfer switch or is it thru a Breaker?
Next question as this equipment is 30 yrs old have you checked term rateings of the connections?? (60% or 75% rateings. (110.14c)Most likely the runs out of Transfer switch (feeders). 310.4 2002 handbook page 259 states one phase can be alum or copper as each phase is treated indepented of the other.
Curious Voltage of this system?? My guess 120/208 Y. ??A lotta unanswered question here???

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