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Mains 3-phase wiring question

M

Mike Cook

Jan 1, 1970
0
In a print shop, the service entrance equipment has three 125A breakers.
These feed three 120/208 breaker panels. There is a fourth space in the SE
panel for another breaker.

We have need to power one new printing press which draws just under 150A. If
the total load calculations work out, is there any reason we couldn't use a
suitable-sized breaker in the SE panel to supply this one load rather than
install another 120/208 breaker panel?

Thanks.
 
M

Martin Riddle

Jan 1, 1970
0
Mike Cook said:
In a print shop, the service entrance equipment has three 125A
breakers.
These feed three 120/208 breaker panels. There is a fourth space in
the SE
panel for another breaker.

We have need to power one new printing press which draws just under
150A. If
the total load calculations work out, is there any reason we couldn't
use a
suitable-sized breaker in the SE panel to supply this one load rather
than
install another 120/208 breaker panel?

Thanks.

It depends upon what the SE panel is rated for. Yes the Panels them
selves have ratings for the bus bars.
Obviously your running 375A so far. Is it a 400A panel or ....
If you pop the cover you should see a tag inside as to what the rating
is. Be careful you got Niagara Falls behind that panel ;)

Cheers
 
J

John S

Jan 1, 1970
0
In a print shop, the service entrance equipment has three 125A breakers.
These feed three 120/208 breaker panels. There is a fourth space in the SE
panel for another breaker.

We have need to power one new printing press which draws just under 150A. If
the total load calculations work out, is there any reason we couldn't use a
suitable-sized breaker in the SE panel to supply this one load rather than
install another 120/208 breaker panel?

Thanks.

Ask your insurance company.
 
M

Mike Cook

Jan 1, 1970
0
You didn't say how much current you are being supplied.
If your SE can handle the extra breaker with safety margin then you
may be fine.
I agree about seeking a licensed electrician.

Tom

Thanks Tom and others for your comments.

Yes, we will consult with an electrician or the Utility to avoid any
assumptions before we do the work.

Cheers!
 
M

Mike Cook

Jan 1, 1970
0
Ask your insurance company.

Insurance is OK with anything within NEC.
 
G

Gary Walters

Jan 1, 1970
0
IIRC, there was one extra slot available for the circuit breaker. How do
you protect a three-phase load that way?

3-pole breaker.
 
M

Mike Cook

Jan 1, 1970
0
IIRC, there was one extra slot available for the circuit breaker. How do
you protect a three-phase load that way?

Ah. OK, technically there's 3 slots available. There are only 3-pole breakers
in this panel so I didn't count individual bus tabs, but 3-pole breaker
locations.
 
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