ECN Forum Forums Code Related Discussion NEC & other Code issues Article 230 Services

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.