400 amp service

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drscott

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I have a 400 amp meter socket fed into 2- 200 amp RT disconnects. Each disconnect then runs to a 200 amp MLO panel in the house next to each other. This is done by each disconnect to panel with a 2" conduit, and 3/0 cu..
Question is. Is this allowed? Does this fit under 230-71 (1999 code).
The house was sized for a 400 amp service, but something is telling me that this isn't quite right.
Doug
 
Re: 400 amp service

I don't see a problem.

408.16 requires the panel to have over current protection on the line side of the panel. The 200amp disconnect mains comply with this code.

230.70 allows the disconnect to be outside of the building.
 
Re: 400 amp service

Why 3/0 to panels ???
 
Re: 400 amp service

WOW I always thought that table 310.15(B)(6) stoped at the service disconect ;)

Now let the inspector just try to give me a red tag for having 2/0 on a 200 amp service between the disconect and the panel. :mad:
 
Re: 400 amp service

Sorry but if it is not the main power feeder, the Code does stop at the service. If you are feeding 2-200 ampere down stream panelboards, neither of them can be the main power feeder. The wire or cable then must be sized from table 310.16. :D
 
Re: 400 amp service

Charlie:
I have to disagree for the sake of education ;)

If article 310.15(B)(6)says

"For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panelboard(s)."

Then you have to be able to extend this application to at least the first panel with the lighting circuits in it at the dwelling

[ February 06, 2004, 12:04 PM: Message edited by: russ ]
 
Re: 400 amp service

Russ I agree with you, however, as you said, after the lighting appliance branch-circuit panel (or panels) any additional panels dowstream of these panels would have to be sized per 310.16

Roger
 
Re: 400 amp service

Sorry guys, I still have to disagree with you on this one. If you have a 200 ampere service on the outside of the home and then run a 200 ampere feeder to the down stream panelboard, that is the main power feeder. I do not see how you can have a 400 ampere service and run two main power feeders. :confused:
 
Re: 400 amp service

Charlie,
For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panelboard(s).
Click to expand...
If the reduced wire size cannot be used in this case why does the code section use the "(s)" after the words feeder and panelboard?
Don

[ February 07, 2004, 10:06 AM: Message edited by: don_resqcapt19 ]
 
Re: 400 amp service

Why is "Main Disconnect" used in that section.

For application of this section, the main power feeder shall be the feeder(s) between the main disconnect and the lighting and appliance branch-circuit panelboard(s).
Click to expand...
Roger
 
Re: 400 amp service

When the code says for example feed(s) the s is bracketed because it singular when singular applies and its plural when plural applies.
310.15(B)(6) covers dwelling services and feeders plural. Because you have two family dwellings and multi family dwelling also covered by 310.15(B) (6) the plural argument is weak at best. In multi family dwellings you would still have more than one feeder and all feeders being the main power feed for the dwelling it serves.

By the way I never thought twice about applying this table to sub panels until reading this forum.


Load itserves changed to dwelling it serves.

[ February 07, 2004, 12:08 PM: Message edited by: david ]
 
Re: 400 amp service

I guess the counter argument could be that the word main disconnect is singular.
Meaning you can have more than one panel(s) off the same disconnect, with out the code specifying they have to be in separate dwellings
 
Re: 400 amp service

Russ, that is correct. The point I'm making is that if 310.15(B)(6) was intended to be used for any (even if from one of the MLO lighting and appliance branch-circuit panelboard(s)) of the dwelling feeder, the term "MAIN DISCONNECT" would not have been necessary in the article.

Roger
 
Re: 400 amp service

I agree with Charlie on this. In previous additions of the NEC the only conductors that were allowed to be sized by 310.15(B)(6) had to carry the total current supplied by the service. I have always felt the (s) was added to permit feeders for multi-family dwellings to also use the sizes shown in this table.
 
Re: 400 amp service

The 200 amp RT disc.is the primary panel downstream are sub panels,that`s why there is no main breaker required on these panels.4 wire system MLO panels good to go.......Each RT disc is its own primary panel same as a 400 back to back with 2 200 main breaker panels and 2 sub panels down the line.I`ve built 100`s of these senarios.
 
Re: 400 amp service

One of the scenarios that the NEC is covering here is for a service disconnect that is installed outside or immediately upon entrance inside the building, and then having a panel installed further inside the building because the panel is too far for the 'upon immediate entrance to the building' requirement.
310.15(B)(6) states the Main feeder conductors do not need to be larger than the service conductors and it only makes sense. Of course this is for dwelling units.

One of the reasons for the plural designation is that one can install two sets of service entrance conductors from a single 400 amp rated meterpan to two separate 200 amp panels, using 310.15(B)(6) to size the conductors.

A question: read the last paragraph.
In the last paragraph I wrote, is that a 400 amp service, or two 200 amp services?
Before answering, read the definitions of service and service equipment in Article 100 ;)

Pierre

[ February 07, 2004, 06:53 PM: Message edited by: pierre ]
 
Re: 400 amp service

OK let's do this.

310.15(b)(6) specifically allows reduction to the first lighting appliance
branch-circuit panel(s) down line of the service equipment.

Lets walk through this. We will use a lateral in this example

400A service
2-200 amp lighting appliance branch-circuit panels.

Service lateral --400KCM copper per article 310.15(b)(6) to meter can.

We still have not made it to our lighting appliance branch-circuit panels
yet.

For sake of coversation we install 2-200 amp enclosed breakers adjacent to
this meter can and feed these from parallel lugs.

We use 2/0 copper per 310.15(b)(6).

We still have not made it to our lighting appliance branch-circuit panels
yet.

We feed 2-200 amp lighting appliance branch-circuit panels with 2/0 copper
per 310.15(b)(6)and make all terminations.

We have finally made it to our lighting appliance branch-circuit panels.

Now 310.15(b)(6) has seen it's end and if we feed any sub panel, say a 100 amp, from one of these aforementioned lighting appliance branch-circuit panels, this 100 amp sub panel can not use 310.15(b)(6)

Roger

[ February 07, 2004, 07:15 PM: Message edited by: roger ]
 
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