Grounded conductor required?

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering
A detached building being fed from another building only needs a 480 volt 3 phase delta feed. Are we required to pull the grounded conductor and land it even though it will not be used?
Code reference please.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
nope - For grounded systems, only have to bring the grounded conductor to the service equipment. 250.24.C

If there are no 277 loads, you don't need it. And it won't make the installation any safer.
 
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Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
I agree- not needed however, it is hard to believe that lighting would not be needed there. I would pull a grounded conductor at least the size of the equipment grounding conductor.

I guess it is possible there will be a separate 240/120 v line also.
 

Adamjamma

Senior Member
Isn’t the restriction over feeds concerned with services of same voltage? Thus a 277 service would not truly work the same as a 120/240 service and would have its own main disconnect etc...
or am I wrong? Because I have seen many businesses served by multiple feeds of differing voltages, and secondary buildings fed from these same services.
 

Adamjamma

Senior Member
Take a look at 225.30(D).

Right.. what I thought.. additional feeders or branch circuits shall be permitted... for different voltages, frequencies, or phases, or for different uses..


which to me means that if the person is using 277 three phase and later adds a second service feed of 120/240 single phase it is allowed... does not violate anything... under the different characteristics provisions...

same as if exceeds a certain amperage at 1 thousand volts..lol...
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
Application is Industrial, Process

Most I see are HRG, 480V systems. So single phase 277V is not available.

Feeders to buildings will be 3ph, 480V, no neutral, healthy EGC - generally feeding an MCC, or 480 panelboard. Lighting loads are dealt with, similar to Charlie's post, except using a 75kva, 3ph, 480D/208Y solid grounded, xfm feeding a 225A, 208/120, panel.

277V single phase loads are usually heat trace. Installation will be a 75KVA, 480D/480Y solid grounded, transformer, feeding a 100A panelboard.
 

Dale001289

Senior Member
Location
Georgia
I agree- not needed however, it is hard to believe that lighting would not be needed there. I would pull a grounded conductor at least the size of the equipment grounding conductor.

I guess it is possible there will be a separate 240/120 v line also.
Yep. Its always a good idea to pull a grounded conductor initially rather than later, at a higher cost.
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Engineering

Or perhaps a step-down, single phase 480 - 120/240V transformer.
This is correct, there will be (2) 480-120/208 xfmr's in the building.
I knew if it was a service it had to have a grounded conductor bought to it and connected. but I wasn't sure about a feeder ran to a detached building.
 
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