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#90981 - 12/20/04 03:42 PM Single Phase or Three Phase?  
rknikko  Offline
Member
Joined: Feb 2004
Posts: 41
NY
Can a residential apt that is about 2200 sq. ft. have three phase service? or is it only for commercial? Is this a NEC issue or local building dept.?


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#90982 - 12/20/04 05:19 PM Re: Single Phase or Three Phase?  
electricman2  Offline
Member
Joined: Nov 2003
Posts: 269
Thomasville, NC USA
It would be up to the POCO as to whether they would or would not make it available.
edit for spelling.

[This message has been edited by electricman2 (edited 12-20-2004).]


John

#90983 - 12/20/04 05:21 PM Re: Single Phase or Three Phase?  
winnie  Offline
Member
Joined: Sep 2003
Posts: 649
boston, ma
This is probably more a power company issue than anything else.

It is unlikely that a residence will have three phase power, with one exception:

Some larger apartment buildings have three phase power. Each apartment has there own panel with a three wire feeder, using two of the phases and the neutral. The wiring inside the apartment looks like single phase, but you only have 208V line to line, and you _always_ have to count the neutral as a current carrying conductor.


-Jon


#90984 - 12/20/04 07:48 PM Re: Single Phase or Three Phase?  
ameterguy  Offline
Member
Joined: May 2002
Posts: 30
Mass
I agree with you John. Our utility will feed condo projects with three phase transformers and feed 2 live legs and a nuetral (network) to the individula units. Our policy is three phase services are only allowed on our commercial or industrial rates, not residential rates.


#90985 - 12/26/04 10:56 PM Re: Single Phase or Three Phase?  
CharlieE  Offline
Member
Joined: Apr 2004
Posts: 200
Indianapolis
For what it is worth, we have some residential 3Ø services. [Linked Image]

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Charlie Eldridge, Indianapolis, Utility Power Guy


Charlie Eldridge, Indianapolis Utility Power Guy

#90986 - 12/28/04 12:34 PM Re: Single Phase or Three Phase?  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
A little off-topic for NEC discussions, but here in Britain 3-phase is very rare for residential. Apartment blocks will take a 3-phase service, but each "flat" will get only a 2-wire single-phase service tapped from the 3-phase risers.

Continental Europe is a different ballgame. 3-phase residential power is very common there, even for quite low-power services.


#90987 - 12/28/04 05:57 PM Re: Single Phase or Three Phase?  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
 
In North America this seems to be a highly regional decision. NEC or local code may prohibit >150V-to-ground in residential structures—limiting interior circuits to 208Y/120V. Three-phase service in single-family homes has become more common in NorCal, for once prohibited at all costs, to permitted if at a commercial tariff, to permitted for larger service, but the cost of all additional {above 1ø} utility-provided facilities paid for prior to a single kilowatthour sold.

In some regions, 3ø single-family residential is old hat. 1200-ampere boards are not unheard of.

There is a home about a mile from me that has a 600-ampere switchboard, with dedicated 75kVA 208Y/120 padmount. Well pump and hermetic refrigeration compressors are 3ø, which clearly have much higher reliability that their 1ø equivalents.

[On Paul’s comments, there was a recent usenet thread re “standard” 15½-ampere 230/400V service for (assumedly single-family) residences in an area of Portugal.]


#90988 - 12/29/04 06:24 AM Re: Single Phase or Three Phase?  
Physis  Offline
Member
Joined: Dec 2004
Posts: 86
Burlingame, Ca. USA
Mr. Eldridge,

I'm going to be ready to bring my newly refitted linear accelerator on line again soon and now this thing's going to need at least 3Ø. Do you have any advice on how I should approach my power company. By the way they are PG&E, If that matters.

Rknikko, I appologize for being off topic.

Editted because I never get it right the first time.

[This message has been edited by Physis (edited 12-29-2004).]


Sam, San Francisco Bay Area

#90989 - 12/29/04 10:22 AM Re: Single Phase or Three Phase?  
CharlieE  Offline
Member
Joined: Apr 2004
Posts: 200
Indianapolis
Hello Sam. Send me a PM on the other forum and I'll give you the name, address, and phone number of a friend at PG&E. [Linked Image]

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Charlie Eldridge, Indianapolis, Utility Power Guy


Charlie Eldridge, Indianapolis Utility Power Guy

#90990 - 12/29/04 06:12 PM Re: Single Phase or Three Phase?  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
 
Phys — You may be in luck. Based on some rules-of-thumb for data-center planning, if you want your own 600-ampere distribution circuit, you can get 12,000kVA of capacity on one of PG&E’s 12kV lines, or, up to 21,000kVA on a dedicated 21kV circuit. [Decent LINACs always need lots of extra focus-magnet power… and, or course, air conditioning on those balmy afternoons.]

If you want to go full tilt, and if it’s in their best interests, PG&E will serve as low as 2,000kVA demand at 69 or 115kV.




[This message has been edited by Bjarney (edited 12-29-2004).]


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