3 wire + neutral + ground service

[j_braddock]

our plant is planning an expansion and some equipment has specified they require 3 wires + neutral + ground.

is this a common power bus system in the states?

i am trying to help out some of the engineers out with some problems and this is one i was given.

also, will the neutral be considered a current carrying wire - i ask for derating purposes.

thanks in advance.

 

[james wuebker]

Re: 3 wire + neutral + ground service

Is this a 480v system or a 240v system?

 

[ryan_618]

Re: 3 wire + neutral + ground service

Yes this is a common setup. To answer your question about the grounded conductor...take a look at article 310.15(4) and you will see that it depends on the types of loads imposed on it.

[ September 15, 2003, 01:38 PM: Message edited by: ryan_618 ]

 

[bennie]

Re: 3 wire + neutral + ground service

You should look at Scott's excellent transformer connection diagrams.

 

[j_braddock]

Re: 3 wire + neutral + ground service

this is a 480 volt 3 phase system.
as far as what it is powering, motors, welders, robots, paint systems, electrical control panels.

bennie,
is there a website link i can goto?

 

[hurk27]

Re: 3 wire + neutral + ground service

Just a thought
If this service is for Europe type equipment keep in mind that our 480 volt Wye is 277 volts to the neutral, and a consultation with the power company engineer might be of some help as he would know what they could supply. You might need a dual service 480 delta and a 208/120 Wye which could be done after the power company's service.

 

[mclain]

Re: 3 wire + neutral + ground service

Really need more information as to the type of system. It is possible that it is a 480 volt delta with one leg center tapped for 240 single phase for control power if this is a European set up.

 

[bennie]

Re: 3 wire + neutral + ground service

J Braddock: Look under "grounding and bonding", "transformer configurations" on this forum.