ECN Forum
Posted By: sparkync 200 amp panel downstream of 90 amp breaker - 08/05/05 02:26 AM
Is there anything in the code that would prohibit using a 200 amp panel with a 200 amp main breaker as a sub panel that is fed by a 90 amp breaker. The reason I would consider using the 200 amp, is to get the amount of circuits that I need in replacing old fuse panels with one breaker panel. The wire size feeding the old fuse panels is probably #2 as far as I can tell at this point ( wasn't able to identify it completely ) but it is fed from a 90 amp breaker. In the event that the load does get up to 90 amps or so, the outside breaker would trip, so the 200 amp is just really used as a means of disconnect for the sub panel, which I know is not really necessary since there is a main outside, but just for convenience purposes, I am thinking on putting one if I can. House belongs a 86 year old man and the panel will be in the basement. My other option would be to run 125 amp wire maybe and put 125 amp panel that might have barely enough room for the circuits. I don't know if I can get a bigger than 125 amp breaker to fit in the 200 amp panel outside or not. Any input would be appreciated. Normally I wouldn't do it like I mentioned above, but I need more circuits than a 100 amp panel can give me.. Thanks .. Steve
Posted By: Tiger Re: 200 amp panel downstream of 90 amp breaker - 08/05/05 04:05 AM
I don't know of any violation in that setup. I've heard of inspectors that won't approve it, so check with the AHJ.

Would a Square D QO, 100-amp, 32 circuit panel work for you?

Dave
Dave, that would work great, if I could find one. I haven't ever seen one with that many circuits around here. Thanks Steve
Posted By: Tiger Re: 200 amp panel downstream of 90 amp breaker - 08/05/05 12:05 PM
I've used them ever since they came out, Steve, which was about two years ago. All the wholesalers here carry them, as well as Home Depot and Menards. I think I'm in the only municipality in the area that still allows a 100-amp residential service.

Dave
Posted By: BobH Re: 200 amp panel downstream of 90 amp breaker - 08/05/05 12:25 PM
Tiger, may I ask why some inspectors will not allow this? It seems to be within code and is not a safety concern. Just curious. Would they allow it if a load calc. was performed? Thanks.
Posted By: nov Re: 200 amp panel downstream of 90 amp breaker - 08/05/05 09:19 PM
cuttler hammer also has a 30 space 100 amp main breaker panel in there CH line. I think it is a good panel if you cant get the QO also slighty cheaper a my supply house anyway
Steve:
How about a 40 or 42 circuit 225 amp main lug only panel??

You have existing main outside, so a MLO panel is acceptable, unless you want to use the 'main' as a disco.

There is no NEC problems with what you propose.

Also, you should be able to get the CH panel as MLO also.

John
I think article 110.3 applies here.

110.3 Examination, Identification, Installation, and Use of Equipment
(A) Examination
(7) Classification by type, size, voltage, current capacity, and specific use

If the main breaker panel you want to use has 200 amp MB rating, and you are feeding it with a 90 amp breaker, then in my opinion this clearly violates current capacity in 110.3(A)(7)
Shockme:

Sounds like you mean having a 90 amp rated panel (if there is/was) on a 200 amp OCP.

MLO panels are commonly used around here for circuit capacity (number of branch OCP devices) 225 amp MLO 40 or 42 circuit panels, with 100 or 125 amp feeds are common.

John
Thanks guys for the input. I found out today at one of the supply houses, that they can order me a Seimans 100 amp 30 circuit from about an hours drive from where I live. This will probably be the route I take, if the homeowner want it done. Lowes or Home Depot in my area don't carry anything over a 20 circuit 100 amp panel, and even the supply houses don't. I wished they did though. This is not the first time I've needed more spaces for a "panel change out".. Thanks again .. Steve

On second thought after reading Curt's post, I might use a 200 amp 30/42 circuit main lug panel just in case in the future the main breaker and feeder needs to be changed, the panel will already be there. Would save the homeowner a little if they want to expand any more.. I checked the prices and they are about the same for a 100 amp. 30 circuit main breaker, as it is for the 200 amp main lug.. Steve
[This message has been edited by sparkync (edited 08-05-2005).]

[This message has been edited by sparkync (edited 08-05-2005).]

[This message has been edited by sparkync (edited 08-05-2005).]
I agree with John. It is perfectly acceptable to use a panel with that has a buss rating higher than the feeder. One thing to be careful about is the lug rating of 200 amp loadcenters since the minimum wire size for many of them is #1. I believe the lugs on 200 and 225 amp Square D loadcenters are rated down to #6.

Curt


[This message has been edited by caselec (edited 08-06-2005).]
Posted By: Tiger Re: 200 amp panel downstream of 90 amp breaker - 08/06/05 01:58 PM
BobH, I don't know if you're asking about the 200-amp main, or the 200-amp minimum service. I've done the setup that Steve describes, and consider it an additional disconnect. Personally I LIKE having an additional disconnect within sight in that situation.

The 200-amp minimum isn't an NEC requirement, but a local amendment. One town will allow 100-amp if you provide load calculations. I prefer to go with the 200-amp service than to do calculations. It's more time involved to make less money and I'd look like a fool if the additional service were needed in the future.

Dave
Posted By: iwire Re: 200 amp panel downstream of 90 amp breaker - 08/06/05 02:30 PM
ShockMe77, you have shocked me. [Linked Image]

Quote
I think article 110.3 applies here.

I think that is a major stretch.

Quote
110.3 Examination, Identification, Installation, and Use of Equipment.

(A) Examination. In judging equipment, considerations such as the following shall be evaluated:

(7) Classification by type, size, voltage, current capacity, and specific use

Notice it says "considerations such as"

Most reasonable people IMO would consider a 200 amp panel to be safe fed with a 90 amp breaker.


Would you require a 200 amp disconnect feeding a 125 amp load to be fed at 200 amps?

Bob
Posted By: Tiger Re: 200 amp panel downstream of 90 amp breaker - 08/06/05 03:04 PM
A similar situation IMO is running a 60-amp AC disconnect at 30-amps.

Dave
ever thought of just useing a main-lug 200A?
© ECN Electrical Forums