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#208706 - 02/07/13 02:10 PM Simple question about voltage and current ratings
piphomer Offline
New Member
Registered: 02/06/13
Posts: 3
Loc: San Francisco, CA
Dear all,

I am new to the industry and new to this forum. So thanks for bearing with me on a simple question!

When a 3-phase electrical box, eg this one is rated at 400A, does that mean 400A per phase, or 400A total i.e. 133A per phase?

Also, this box for example is rated as 600V - does that mean phase to phase, or each phase to neutral?

Many thanks!!

-Phillip
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#208707 - 02/07/13 03:41 PM Re: Simple question about voltage and current ratings [Re: piphomer]
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9039
Loc: Estero,Fl,usa
That is 400a per phase. The 600v is phase to phase.
For a 600v wye, l/n would be 347 as would be the wild leg of a center tapped 600v delta although I have never heard of doing it.
Typically you see 480v as the high end of "low voltage". (a multiple definition term itself)
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Greg Fretwell
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#208708 - 02/07/13 06:03 PM Re: Simple question about voltage and current ratings [Re: piphomer]
piphomer Offline
New Member
Registered: 02/06/13
Posts: 3
Loc: San Francisco, CA
Thanks!

So does that mean that for a 230V phase-phase (400V phase-neutral) system with a max current per phase of 160A, I actually can use a DH324NRK instead of the one in the previous link? Or do I have to go to the DH364NRK as I have 400V phase-phase so need the 600V capacity? Based on this cut sheet?

Thanks so much!
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#208717 - 02/07/13 07:39 PM Re: Simple question about voltage and current ratings [Re: piphomer]
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9039
Loc: Estero,Fl,usa
If you have a 240v 3p with a 160a computed load the xx324xxx sounds like it is your panel with a 200a breaker using the appropriate conductors. If you had diversity and non continuous loads you could step down to 175a
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Greg Fretwell
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#208724 - 02/08/13 03:11 AM Re: Simple question about voltage and current ratings [Re: piphomer]
Tesla Offline
Member
Registered: 06/16/04
Posts: 1273
Loc: Sacramento, CA
piphomer: You're too green to be an EE, C-10 or certified electrician.

At this scale of power use -- turn the matter over to professionals.

There are too many issues for you to 'get it right' over the Internet.
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Tesla
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#208732 - 02/08/13 11:34 AM Re: Simple question about voltage and current ratings [Re: Tesla]
piphomer Offline
New Member
Registered: 02/06/13
Posts: 3
Loc: San Francisco, CA
Agreed. Thanks.
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