3 panels - 400 amp service

Reply

  #1  
Old 07-13-05, 12:04 PM
Skapare's Avatar
Member
Thread Starter
Join Date: Jun 2004
Location: USA
Posts: 198
3 panels - 400 amp service

Actually my initial rough load calculations come in under 200 amps, but it might make sense to do 400 amp service anyway. But that's the tops; no more than 400 amps.

The circuit count (240 volt counts as 2) comes in at 90 circuits (there are a lot of rooms in this design, including 6 bedrooms, 4 of which have private baths and a loft). So that means at least 3 panels (2 panels would limit to 84 circuits with no room leftover at all). I would expect to put in 200 or 225 amp panels, each with it's own main breaker.

For various reasons, I'm planning to put the 3 panels together in an electrical room on the first floor. What I'm wondering about are what common methods are used to connect these panels to the service. Since the sum of the panel capacity is larger than the service capacity, I'm planning to have a single separate main breaker for the whole service. But I'd like to know how that gets connected to the 3 panels so I can figure in what size of room it would need in the design.

Also, I'd like the 3 panels in a room toward the center of the house. So that means the main breaker would not be near them so it can be located at the point of entrance so no unprotected wiring is inside.

I'm wondering if I need a separate enclosure for the junction, and how big it would need to be. I believe a terminal block would be needed; I definitely would not want any pigtail type junction on wires this size (4/0 through 600 kcmil). But how large of an enclosure would that need to be?
 
Sponsored Links
  #2  
Old 07-13-05, 12:40 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
If you go with 200-amp service, the 200-amp breaker in the main panel will be the disconnect for the building. The panel housing the main breaker will be the main panel. I suggest you go ahead and use a full panel here rather than just a disconnect. All other panels will be subpanels. Each subpanel will connect to a double-pole breaker in the main panel, using a three-wire plus ground feeder. The neutral and grounding bars will be bonded in the main panel and unbonded in the subpanels. If possible, keep all your large loads in the main panel, and use the subpanels for lighting and receptacle circuits only.
 
  #3  
Old 07-13-05, 03:53 PM
Member
Join Date: Feb 2002
Location: port chester n y
Posts: 2,117
I doubt if you can make any firm decisions until you determine what the POCO requires for metering-equipment for a service in excess of 200 amps.

Possible options;--- an single enclosure , out-door, with a meter-socket and two 200 amp breakers; ----a C-T cabinet;----- a 400 amp enclosure with a Service Dis-connect and connections for C-T's.

All must be POCO approved.

Good Luck & Enjoy the Experience!!!!!!!!!!
 
  #4  
Old 07-14-05, 08:27 AM
Skapare's Avatar
Member
Thread Starter
Join Date: Jun 2004
Location: USA
Posts: 198
Originally Posted by John Nelson
If you go with 200-amp service, the 200-amp breaker in the main panel will be the disconnect for the building. The panel housing the main breaker will be the main panel. I suggest you go ahead and use a full panel here rather than just a disconnect. All other panels will be subpanels. Each subpanel will connect to a double-pole breaker in the main panel, using a three-wire plus ground feeder. The neutral and grounding bars will be bonded in the main panel and unbonded in the subpanels. If possible, keep all your large loads in the main panel, and use the subpanels for lighting and receptacle circuits only.
If I go with 200 amp service, it's rather obvious that one of the 200 amp panels can be the main and I can just run 2 subpanels from it. But since I'm looking at designing it for 400 amp service, I'm looking away from that option. How would it be done with 400 amp service where all the branch panels are at most 225 amp.
 
  #5  
Old 07-14-05, 08:31 AM
Skapare's Avatar
Member
Thread Starter
Join Date: Jun 2004
Location: USA
Posts: 198
Originally Posted by PATTBAA
I doubt if you can make any firm decisions until you determine what the POCO requires for metering-equipment for a service in excess of 200 amps.

Possible options;--- an single enclosure , out-door, with a meter-socket and two 200 amp breakers; ----a C-T cabinet;----- a 400 amp enclosure with a Service Dis-connect and connections for C-T's.

All must be POCO approved.

Good Luck & Enjoy the Experience!!!!!!!!!!
Since I do want to have a single disconnect for the whole service, I doubt their method of metering would matter. Either way, whether it is a standard plug-in meter, or current transformers, there would be one set of wires coming from it.

Part of the idea is to design it so that if I do go with just 200 amp service to begin with, it won't be any major change of organization to upgrade to 400 amps. Letting the POCO change the meter, and I change the main disconnect, would be obvious. What I want to avoid (and why I ask about 400 amp) is some setup that can be done with 200 amps (such as one panel being main and the other 2 being subs) but can't be simply converted to handle a 400 amp service.

What I envision is one set of wires (perhaps 600 kcmil) coming from the meter enclosure (in conduit) to the main disconnect located very close to the meter (due to elevations it can't quite be back to back, but there woudn't be more than about 2 feet inside and it would all be in conduit and the main disconnect enclosure). That disconnect would be overcurrent protection suitable for the run from there to the 3 panels. So potentially that would be the same size wire going from the disconnect to the 3 panels located in an interior room.
 
  #6  
Old 07-14-05, 10:14 AM
Member
Join Date: Feb 2002
Location: port chester n y
Posts: 2,117
Will the Service Conductors that extend from the POCO's conductors to the premises be over-head ( "Service Drop" ) or underground ( "Service Lateral" ) ?

I suggest you committ to a 400-amp Service instead of trying to design a 200 amp Service than can be "converted" to a 400 amp Service.

Metering equiptments aside, and with 400 amp Service Entrance Conductors, terminate the SEC's in a Wiring Gutter, say 6" sq. X 3 ft. and extend two 200-amp "tap-conductors" to the Line terminals of two 200 amp panels , each equipted with 200 amp "Main -Breakers". The two MCB's are the Service Dis-Connects.

You can now extend four 100 amp Feeders to Load -Centers located where most convenient.The Wiring Method for the Feeders can be Non-Metallic cable, or raceways underneath the slab which is the celllar floor.
 
  #7  
Old 07-14-05, 10:50 AM
Skapare's Avatar
Member
Thread Starter
Join Date: Jun 2004
Location: USA
Posts: 198
Originally Posted by PATTBAA
Will the Service Conductors that extend from the POCO's conductors to the premises be over-head ( "Service Drop" ) or underground ( "Service Lateral" ) ?
Probably underground. That's the way I would want to have it.

Originally Posted by PATTBAA
I suggest you committ to a 400-amp Service instead of trying to design a 200 amp Service than can be "converted" to a 400 amp Service.
I probably will for all the parts not easily changed out, such as the underground feed.

Originally Posted by PATTBAA
Metering equiptments aside, and with 400 amp Service Entrance Conductors, terminate the SEC's in a Wiring Gutter, say 6" sq. X 3 ft. and extend two 200-amp "tap-conductors" to the Line terminals of two 200 amp panels , each equipted with 200 amp "Main -Breakers". The two MCB's are the Service Dis-Connects.
How would the wires be tapped together in that wiring gutter? I don't want pigtail type connections involved. What about a terminal block if one can be found that big? Something with a single 600 kcmill hole and 3 4/0 holes times 4 (line, line, neutral and ground). Or maybe copper welding?

Originally Posted by PATTBAA
You can now extend four 100 amp Feeders to Load -Centers located where most convenient.The Wiring Method for the Feeders can be Non-Metallic cable, or raceways underneath the slab which is the celllar floor.
I don't know if this is what you meant, but I will be avoiding any wiring under the basement slab. The panels won't be in the basement, except maybe for a subpanel specifically to serve circuits in the basement itself. The first floor, which will actually be about 6 feet above grade level where the service entrance will be, will (more toward the center of the house) have the panels in a utility room.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes