Section 230.2(D):

Question:

Please give an example of when an additional service is permitted because of different voltage, frequencies, or phases.

Please Explain "Such as" ... ?

Joe,

Had a Doctor for a customer that added an X-ray machine to his practice. That equipment needed a 3 phase service, so we ended up with 120/240 single phase service and a 120/240 3 phase 4 wire service to the same building.

Another contractor ended up doing something similar on a truck stop remodel to keep from building a 400 amp 3 phase service. Built two 200 amp services like the example above and saved the owner some money.

You're on your own for "such as"

Tom

The handhook expands on that;
"For different applications, such as different rate schedules, this requirement allows a second service for supplying a second meter on a different rate. Curtailable loads, interruptible loads, electric heating, and electric water heating are examples of loads that may be on a different rate."

I am not sure why that needs another service (they can simply split the metering after the drop) but since this is a utility decision it is really out of our hands.
Another place I could see 2 services is if the primary loads come in on a medium voltage drop with customer owned transformer and they want some 240 for their firepump.
I did see that once. I think the emergency panels ran off that too, with transfer equipment to the genny, but it was a while ago so I am not sure about that.

Like in Toms post, I have a customer with a carpet/tile sales building with a 120/240 single phase service and they needed 480 3 phase 4 wire service to the same building for a granite cutting machine he was setting up to do counter tops.So I added the 2nd service to the place and located it on the opposite side of the building too.
I asked for permission to add the 2nd service from the AHJ. I also placed plaques denoting the other service at each.
shortcircuit

Any of the multiple service buildings I have been involved with have either needed additional capacity or it just did not make sense to bring all the power in on one side of the building only to have to bring 50% of the capacity across to the other side.

Sometimes it is truly multiple services other times multiple feeders.

We did a large refrigerated / mechanized warehouse with 7- 3000 amp 480 volt switch gears. I believe that one was feeders.

I was involved with a building in Somerville MA that had.

In the electric room

1- 4000 amp 208 service

1- 3000 amp 480 service

And up on the roof (13.8 KV up to the roof in concrete encasement)

3- 3000 amp 480 services.


Bob

I added a 400A 120/240 single phase service in a golf cart storage building to power the battery chargers when they went from gas to electric carts. Original service was 120/208 3Phase 100A.

OK Some more examples:

DC Service for older elevators, and machinery, I see alot of these around here.

And, my wifes building is a Disaster Control Center, and is fed from three different POCO line souces and two sets of back-up generators. (Only uses one at a time, but essentialy four back-ups)

OH Bob, I grew up in Slumerville, and E. Cambridge.

A building with apartments 2nd floor and above, the first floor added a pizza parlor. The original service is 208y/120v- single phase. The pizza place needed 3 phase, and we installed it.

Pierre

Re: 230-2(d)
it is fairly common to see older industrial buildings in our city that have 120/240/1ph or 24/3 delta; with additional 120/208/3 or 277/480/3 added for the requirements of the current business occupying the space.
Now that I work for the city Fire Dept. I really see a lot more of the reason for 230-2; especially 230-2 (e). In a fire emergency, the Fire dept. will kill the power prior to fire suppression. If there are multiple services with PERMANENT signage (not to be confused with felt pen labeling), they can ID all the services, at night, in smoke, and successfully kill all the power.
Better still:
One service point-multiple voltage/phase as required, all in one place, all clearly labeled with PERMANENT SIGNS.
Even better still:
Upgrade service; with feeders & XFormers's for lower voltages and single phase.
It's only money, but cheap safety.
It's liable to be more efficient power distribution, with consequent lower electric bills.
Additional comment about labeling:
CA Fire Code (2000 UFC) art. 85-requires Electrical Rooms and Mains to be labeled with legible and plainly visble signs (see "at night, in smoke" above.
Thanks for all the inputs, on all the NEC issues, all of you; I learn something every day.

Thanks for all of the replies and information.

Maybe I'm getting cranky in my old age but I have this pet peeve about people refering to 120/240 3 phase. If we look in IEEE dictionary we will find that the proper identification of voltage systems would be to label them with the higher voltage first and the lower voltage second if is a multi voltage 3 phase system. 240/120 3 phase is proper for a 3 phase system. 120/240 single phase would be proper for a multi voltage single phase system. Engineers foul this up constantly. I know the correct way of labeling it and I'm just a lowly electrical inspector.

[This message has been edited by George Little (edited 11-22-2004).]

[This message has been edited by George Little (edited 11-23-2004).]

Amen:

220.2 Computations.
(A) Voltages. Unless other voltages are specified, for purposes of computing branch-circuit and feeder loads, nominal system voltages of 120, 120/240, 208Y/120, 240, 347, 480Y/277, 480, 600Y/347, and 600 volts shall be used.

George,
Your pet peeve is correct. I stand corrected: i.e. 480/277; 240/120; 208/120.
(In fact, I used to be more of a stickler for such things, but memory goes with age, I suppose. I can't remember)

Joe,

Not for nothing, but has anyone ever worked on a 347 volt system? I myself have worked on many differnet sytems but never a 347 volt one? My old boss even worked on stuff at different freq. I believe he worked on not just 60/50 hz but he also worked on stuff up to 400 hz. He did tell me that BOY, the 400 stuff really packed a punch when you got hit by that stuff.

I believe the 347/600 volt services are common in Canada.

120/208 3 phase 400 hz is standard aircraft power for most US made aircraft. Have worked on buildings that have motor generators to change the 60 hz to 400 hz to power the aircraft or associated equipment. Usually this is set up as a seperatly derived system but sometimes one 400 hz generator will feed more than 1 building.
And ya 400 hz bits worse than 60hz.

They used 400hz in big computer rooms since the 60s. It is getting phased out but you still see some.