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07-30-2011, 05:02 PM
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#1
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Member
Join Date: Dec 2007
Location: Broward Co., Florida
Posts: 89
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Two feeders, one main disco
Here's the situation;
Meter room located right behind the retail space being worked on. 400 amp 3 phase meter, 400 amp fused disconnect in meter room.
Inside space is one 400 amp panel, and one 225 amp panel, both are MLO. Plans called for the 225 amp panel to be fed from the 400 amp panel, but I am having trouble locating a 225 breaker to fit into the 400 amp panel.
Kicking around ideas I thought of putting in double lugs at the 400 amp main disco, and send 4/0 to the 225, and 600s to the 400, both originating from the same main disco (which is fused at 400 amp). I would then install a 225 amp main breaker into the 225 amp panel. Both panels are about 5 to 10 feet away from the main disconnect.
I am thinking about reasons this can't be done, and kind of compare it to a feeder tap situation, anyone see any code violations in this arrangement?
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07-30-2011, 06:09 PM
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#2
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Senior Member
Join Date: Jan 2009
Location: MA
Posts: 1,357
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Quote:
Originally Posted by nyerinfl
Here's the situation;
Meter room located right behind the retail space being worked on. 400 amp 3 phase meter, 400 amp fused disconnect in meter room.
Inside space is one 400 amp panel, and one 225 amp panel, both are MLO. Plans called for the 225 amp panel to be fed from the 400 amp panel, but I am having trouble locating a 225 breaker to fit into the 400 amp panel.
Kicking around ideas I thought of putting in double lugs at the 400 amp main disco, and send 4/0 to the 225, and 600s to the 400, both originating from the same main disco (which is fused at 400 amp). I would then install a 225 amp main breaker into the 225 amp panel. Both panels are about 5 to 10 feet away from the main disconnect.
I am thinking about reasons this can't be done, and kind of compare it to a feeder tap situation, anyone see any code violations in this arrangement?
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I don't see a problem with this, but I would use 500's for the 400 amp panel.
__________________
Cathedra mea, regulae meae
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07-30-2011, 06:23 PM
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#3
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Senior Member
Join Date: Nov 2007
Location: Miami Fla.
Posts: 2,280
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Quote:
Originally Posted by nyerinfl
I am thinking about reasons this can't be done, and kind of compare it to a feeder tap situation, anyone see any code violations in this arrangement?
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Its a tap.
Quote:
240.2 Definitions.
Tap Conductors. As used in this article, a tap conductor is defined as a conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4.
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07-30-2011, 06:26 PM
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#4
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Senior Member
Join Date: Nov 2007
Location: Miami Fla.
Posts: 2,280
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Sorry, didn't notice the 5' to 10'. If the "conductor length" is 10' or less your golden.
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07-31-2011, 08:24 AM
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#5
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Town Drunk
Join Date: Jan 2007
Location: Baltimore, MD, USA
Posts: 3,716
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Quote:
Originally Posted by tkb
I don't see a problem with this, but I would use 500's for the 400 amp panel.
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As long as the calculated load is 380 amps or less - which it should be if there are a 400 amp panel and a 225 amp panel on 1 400 amp service
__________________
John from Baltimore
"One day at a Time"
All responses based on the '08 NEC
It's not my fault, it's not my problem, I'm not your solution. 
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07-31-2011, 09:39 AM
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#6
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Member
Join Date: Dec 2007
Location: Broward Co., Florida
Posts: 89
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Quote:
Originally Posted by JohnJ0906
As long as the calculated load is 380 amps or less - which it should be if there are a 400 amp panel and a 225 amp panel on 1 400 amp service
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The sub-panel is installed because of needed breaker positions, bunch of 3-phase equipment. The plans call for 600s that is why they are being figured.
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07-31-2011, 10:05 AM
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#7
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Senior Member
Join Date: Nov 2007
Location: Miami Fla.
Posts: 2,280
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Quote:
Originally Posted by nyerinfl
The plans call for 600s that is why they are being figured.
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Plans drawn by Kamm by any chance?
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07-31-2011, 11:10 AM
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#8
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Senior Member
Join Date: Jan 2009
Location: MA
Posts: 1,357
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Quote:
Originally Posted by nyerinfl
The sub-panel is installed because of needed breaker positions, bunch of 3-phase equipment. The plans call for 600s that is why they are being figured.
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That was based on the 225 amp panel running through the 400 amp panel and feeder.
Now they both go directly back to the 400 amp disconnect. The load will lighter on the 400 amp panel. There is no need for 600's going to the 400 amp panel.
The extra cost of the added length of the 225 amp feeder offsets the cost reduction of downsizing to the 500's for the 400 amp panel.
Since you are adding a breaker to the 225 amp panel instead for the 400 amp panel, that cost should be a wash.
__________________
Cathedra mea, regulae meae
Last edited by tkb; 07-31-2011 at 11:20 AM.
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07-31-2011, 11:33 AM
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#9
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Member
Join Date: Dec 2007
Location: Broward Co., Florida
Posts: 89
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Quote:
Originally Posted by Chris Kennedy
Plans drawn by Kamm by any chance?
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Not familiar with Kamm, just another architect.
On a side note the 225 panel was specced as (4) 3/0 and #6 ground. Typical. 
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07-31-2011, 02:02 PM
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#10
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Senior Member
Join Date: Sep 2009
Location: WA
Posts: 4,064
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Does the load really need 225 amps? Perhaps you can get the engineer to chage it to a 200 amp panel?
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07-31-2011, 03:17 PM
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#11
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Senior Member
Join Date: Jan 2009
Location: MA
Posts: 1,357
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Perhaps you could get double lugs in the 400 amp panel so you could feed the 225 amp panel with a main circuit breaker.
__________________
Cathedra mea, regulae meae
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