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Old 11-18-2012, 09:39 PM   #1
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Can I use a breaker on the buss as the panel main?


Hi folks, I've got a lot of electrical archaeology in my place that I'm trying to figure out, even after a decade. Hereís the current stupid and scary situation brought to my attention as I contemplated adding a new subpanel: I think the main panel for my apartment is dangerously out of code. Itís a QO series L5, 6 circuit panel wired directly to the meter by #4 THW, and has no main on board. So it suddenly became obvious thereís technically nothing stopping me from adding another 60A 2 pole breaker, and being able to run way more than the 85A the #4 is rated. The next protection is the 150A building main, not good. Iíve looked at this thing for years without realizing this. Fortunately, with gas heat and range, there's nothing been pulling much serious power.

Iím now thinking the panel was probably swapped out for the original 2 pole main on the service by the buildings previous owners (who were not the swiftest) when they wanted to add some circuits. Another clue is the fact that itís upside down! Why this was done has puzzled me for years, my best guess is they didn't have enough wire from the meter to reach the main lug if it was right side up. So now you push them DOWN to reset!

Unfortunately a normal size load center with a built in mains canít possibly fit in the space, itís only 16Ē from the top of the meter pan to the joist above. Is there any reason I canít simply use an 80A 2 pole breaker on the buss as a main as long as I label it clearly? I recall seeing other panels set up like that. Then Iíd have room for 2 more 2 pole breakers for the subpanels. But maybe there was more to it on those panels that I didn't catch. Or if someone can suggest a small panel with a mains that will fit, that would work too. Iíve perused the Schneider catalog without success.

Thank for any thoughts.

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Old 11-18-2012, 10:25 PM   #2
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Can I use a breaker on the buss as the panel main?


GET A LICENSED ELECTRICIAN,,,,,, and no you cant do the breaker part ,, breakers only work one way it would be a hazardous setup.

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Old 11-18-2012, 10:30 PM   #3
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Can I use a breaker on the buss as the panel main?


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GET A LICENSED ELECTRICIAN,,,,,, and no you cant do the breaker part ,, breakers only work one way it would be a hazardous setup.


Not really!
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Old 11-18-2012, 11:02 PM   #4
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Can I use a breaker on the buss as the panel main?


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GET A LICENSED ELECTRICIAN,,,,,, and no you cant do the breaker part ,, breakers only work one way it would be a hazardous setup.

It's done all the time....but the breaker needs to be rated for that backfeed application. Many panels are designed that way.
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Old 11-18-2012, 11:04 PM   #5
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Can I use a breaker on the buss as the panel main?


GOt a picture of that panel? It might be a split-bus design ....
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Old 11-19-2012, 12:23 AM   #6
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Can I use a breaker on the buss as the panel main?


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GOt a picture of that panel? It might be a split-bus design ....
Thanks Sparky, but on your prodding for pics I found the answer I was looking for on the inside of the panel cover (duh!), and it's mixed. I can put on a main and make it right and safe, but it leaves room for only 1 double pole breaker. What a weird panel. Is there anything else out there this small that would do what I need?

While you're looking, can you comment about the 8/3 BX coming in from a (pro installed) subpanel. I thought it now needed to be MC with the ground, that using the armor for ground was now no-go.

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Old 11-19-2012, 07:03 AM   #7
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Can I use a breaker on the buss as the panel main?


Can you put in heavier service wires from this panel to the meter?

Then you could omit a main breaker here and install another double breaker for another subpanel. (This panel will stay as your main panel and is limited to six breaker handles.)
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Old 11-19-2012, 07:04 AM   #8
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Can I use a breaker on the buss as the panel main?


OK a couple of things:

First, that panel is a 6-space panel, and with 6 or less breakers in it, does not require a main. Each breaker is considered a "service disconnect" and you are allowed up to 6.

You would only be required to use a main if the number of connected circuits exceeded 6.

Second, so-called "BX" is a recognized wiring method. Even today. No violation here.

Lastly, that panel appears to be upside-down, unless your photo is uploaded backwards. That is a violation.
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Old 11-19-2012, 08:41 AM   #9
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Can I use a breaker on the buss as the panel main?


And to add to your problems, you said apartment building. Are you the owner of the building? Are you a licensec electrician? Apartment dwellers can't do their own electrical work.
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Old 11-19-2012, 12:21 PM   #10
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Can I use a breaker on the buss as the panel main?


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OK a couple of things:

First, that panel is a 6-space panel, and with 6 or less breakers in it, does not require a main. Each breaker is considered a "service disconnect" and you are allowed up to 6.

You would only be required to use a main if the number of connected circuits exceeded 6.
I guess I don't get it. That way you could easily have more load than the 100A box rating even if the feed was upgraded as Allan suggested. To do as you suggest "as is" wouldn't I have to keep the combined breaker load under the 85A #4 rating? Currently that sub to my kitchen is getting 40A and I was planning a 60A sub for the basement. In general I don't expect those kinds of loads, but I do have a 220V stick welder. Would the "round up" wire rating principle get me a 40 & 50?

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Second, so-called "BX" is a recognized wiring method. Even today. No violation here.
I guess I heard wrong! I thought it was now OK for equipment but not for subpanels
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Lastly, that panel appears to be upside-down, unless your photo is uploaded backwards. That is a violation.
As I suspected in paragraph 2 of my OP.

Missouri: Yes I am owner, no I'm not a licensed electrician, and I'm just planning this, not installing it. Please don't be insulted if you're a contractor, but as owner of several multifamilies I've hired all sorts of licensed contractors who even if they're capable of doing the work, are incapable of making the most efficient overall plan, rather than the one that's easiest for them, most profitable, or uses the most familiar hardware. I've even had to have thousands of dollars of work ripped out. Investing my time in this way seems reasonable, and the normal process doesn't always protect. That kitchen subpanel install was done under license & permit, the contractor never commented on the upside down main panel, and the city never looked at it, just the new panel upstairs!

Edit: This QO panel "looks" like the ticket, the Schneider site confirming it's OK to set up with a backfeed main. http://products.schneider-electric.u...countryCode=us

Last edited by dirtynails; 11-19-2012 at 01:22 PM. Reason: more info
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Old 11-19-2012, 07:11 PM   #11
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Can I use a breaker on the buss as the panel main?


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I guess I don't get it. That way you could easily have more load than the 100A box rating even if the feed was upgraded as Allan suggested. To do as you suggest "as is" wouldn't I have to keep the combined breaker load under the 85A #4 rating? Currently that sub to my kitchen is getting 40A and I was planning a 60A sub for the basement. In general I don't expect those kinds of loads, but I do have a 220V stick welder. Would the "round up" wire rating principle get me a 40 & 50?
...
You are confusing maximum branch circuit capacity with service capacity.

The service size is not determined by the sum of the ratings of the branch circuit breakers. If you were running everything at maximum rating as you are suggesting, I'd wager you could not afford the electric bill.

There is something called demand factors which are applied when calculating recommended service capacity. When you factor in total load demand, the service capacity is well within limits in most cases.

But, if it makes you feel good, go ahead and put in a "main" breaker. Be sure to install a breaker retaining kit when installing a breaker that is back-fed as a main.
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Old 11-19-2012, 08:32 PM   #12
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Can I use a breaker on the buss as the panel main?


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You are confusing maximum branch circuit capacity with service capacity.

The service size is not determined by the sum of the ratings of the branch circuit breakers. If you were running everything at maximum rating as you are suggesting, I'd wager you could not afford the electric bill.

There is something called demand factors which are applied when calculating recommended service capacity. When you factor in total load demand, the service capacity is well within limits in most cases.

But, if it makes you feel good, go ahead and put in a "main" breaker. Be sure to install a breaker retaining kit when installing a breaker that is back-fed as a main.
I understand what you say as it relates to a load center protected by a main: you can have 1000A of breakers on #6 as long as it's protected by a 60A main. But if you have no main and the amp capacity in the breakers exceeds the ampacity of the feed wire, it seems to violate everything logical about how the system protections are supposed to work, as in never letting you draw more than the smallest feed capacity, however unlikely it is to draw that much.

Anyway, so you don't see any problem with using that new panel. I saw the PK2MB retaining kit was specified for mains. I can use an 80A main, have no problems with 40A & 60A subpanel breakers, and still have 4 circuits free for the boiler such. Oh, and have it installed right side up.

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Last edited by dirtynails; 11-19-2012 at 08:38 PM.
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