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#9802 - 05/14/02 07:13 AM Feeding two load centers from one disc.
ayrton Offline
Member

Registered: 12/21/01
Posts: 205
Loc: Pa
Where in the code could I find whether or not I can feed two main lug load centers from one disconnect? One panel will not hold all the circuits I need, so I want to use one correct amp rated disconnect for my service and two main lug load centers. I looked in 230 and 408 and I cannot find where it says I can't do it. Something in my gut though says it is illegal.

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#9803 - 05/14/02 07:33 AM Re: Feeding two load centers from one disc.
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
As long as the OCPD at the disconenct protects each panel at or below its rated ampacity, I see no problem with this. You just can't use a 400 amp OCPD to supply 2 200 amp MLO panels. You would have to use a 200 amp OCPD to supply the 2 200 amp MLO panels.
Don(rsqcapt19)
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#9804 - 05/14/02 02:20 PM Re: Feeding two load centers from one disc.
DLinton Offline
Member

Registered: 03/19/02
Posts: 19
Loc: Holcomb, KS. USA
I may be in left field. But you can use one disconnect for two panelboards as long as the panel has LESS than 10% of its branch circuits hooked to a neutral (lights and appliances). For example panelboards supplying 480, 220 or 208 loads (Welders in a shop). But the main must not be rated more than the panelboards. Again maybe I'm in left field but that is what I get out of 408.
Dan

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#9805 - 05/14/02 04:45 PM Re: Feeding two load centers from one disc.
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
Dan,
I don't agree. I don't see anything in 408.16(A) or (B) that requires the panel OCPD to be in the panel. It only requires that the panel be protected on [b/the supply side[/b]. In my opinion a remote disconnect is on the supply side and, provided that the disconnects OCPD has a rating equal to or less than that of the panel, meets the rule in 408.16.
Don(resqcapt19)
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#9806 - 05/14/02 07:41 PM Re: Feeding two load centers from one disc.
Electric Eagle Offline
Member

Registered: 04/20/02
Posts: 928
Loc: Alpharetta, GA
How many extra circuits do you have? If you have enough to just about fill up 2 -200 amp panels, then I think you should use a 400 amp service or at least 300, but if you are only say 15 circuits over full, I would put in a 100 -24 circuit amp sub panel.

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#9807 - 05/14/02 08:38 PM Re: Feeding two load centers from one disc.
The Watt Doctor Offline
Member

Registered: 12/23/01
Posts: 443
Loc: Mont Belvieu, TX
"Nurse, hand me that medical journal please. Yes, the one that says "NEC" on it." Notice the following:
384-16. Overcurrent Protection (a) Exception No. 1: Individual protection for a lighting and appliance panelboard shall not be required if the panelboard feeder has overcurrent protection not greater than the rating of the panelboard. If the disconnect is fusible, you can set two MLO panels, and feed thru one of them. Just make sure that you order feed thru lugs for one of them. There is a great picture of this in the "Handbook" on page 390 figure 384.3.
Remember, good electric today, keeps The Watt Doctor away.

Wattological Regards,
Doc
_________________________
The Watt Doctor
Altura Cogen
Channelview, TX

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#9808 - 05/15/02 09:26 AM Re: Feeding two load centers from one disc.
DLinton Offline
Member

Registered: 03/19/02
Posts: 19
Loc: Holcomb, KS. USA
Don,
You are right. I thought that is what I said one disconnect for two panels the 10% was to qaulify what a power panelboard was. (Disconnect) meaning: disconnect means inside or outside of the panels. 408.16B The overcurrent protective device shall be located within OR at any point on the supply side of the panelboard. 408.15 States that one panelboard will not have over 42 overcurrent devices inside it, not counting those provided for in the mains. This restricts how many overcurrent devices in a panel not how many panels. So since the NEC does not state you CAN NOT have more then one panelboard, the limit then falls to the size of the main overcurrent protective device supplying the panelboards based on thier amperage size. For example 1 or more panelboards with a rating of 200 amps must have a 200 amp main. 1 or more panelboards with a couple of 400 amp and 1-200 amp must be served by a 200 amp main.
Dan.

Doc,
I believe 408.16 in the 2002 NEC is the same as 384-16 in the 1999 NEC except for one line stated above about where the overcurrent device shall be located.
Dan
(Remember I'm not a doctor or inspector just an instructor which is probably the lowest on the "telephone/power pole" uhh totum pole)

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#9809 - 05/16/02 08:48 PM Re: Feeding two load centers from one disc.
The Watt Doctor Offline
Member

Registered: 12/23/01
Posts: 443
Loc: Mont Belvieu, TX
Mr. Linton,
You'll have to forgive me. I have a copy of the 2002 NEC, but the AHJ in my city won't adopt the '02 NEC until the end of the year. So, even though the new code is out, I still use the '99 code. I have discussed on this forum the subject of "lighting and applicance" panelboards, and "power" panelboards, and I still believe that what the NE code classifies as a power panelboard should have a main disconnect in it. IMHO, if the panelboards that Mr. aryton is refering to, are "lighting and applicance" panelboards, then he can "feed thru" one to the other with a "remote" fusible disconnect. I am still refering to the '99 code. If the rules have changed in '02, just let me know and I'll crawl back under my rock.
Always remember that good electric today keeps the Watt Doctor away.

Many Watts to All,
Doc
_________________________
The Watt Doctor
Altura Cogen
Channelview, TX

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#9810 - 05/17/02 06:32 AM Re: Feeding two load centers from one disc.
JBD Offline
Member

Registered: 07/12/01
Posts: 599
Loc: WI, USA
The answer to the original question is Yes. A single disconnect (OCPD) can feed multiple panelboards. The OCPD may be located anywhere on the supply side of the panels. The only restriction is; as each panel must be the same ampere size, or larger, as the OCPD.

Doc,
I agree with you that all panels which contain a neutral conductor, except for Service Entrance equipment, must have a main OCPD.

NEC99 384-16b) Power Panelboard Protection. "... a power panelboard with supply conductors that include a neutral ...shall be protected on the supply side by an overcurrent protective device ..."

However I disagree with your statement "disconnect in it". One of the differences in the '99 and '02 codes has to do with the location of the OCPD. The '02 codes clearly allows "remote" mounted main OCPDs.

.

[This message has been edited by JBD (edited 05-17-2002).]

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#9811 - 05/17/02 07:50 AM Re: Feeding two load centers from one disc.
resqcapt19 Offline
Member

Registered: 11/10/00
Posts: 2209
Loc: IL
JBD,
So a remote OCPD is "not on the supply side" of the panel? I find nothing in either the '99 or '02 code that requires the OCPD for any panel to be in or even near the panel itself.
Don(resqcapt19)
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Don(resqcapt19)

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