Different panelboard

steve66

steve66

Senior Member
Location
Illinois
Occupation
Engineer
Is this a split bus panel?

At first it looks like a regular panel, except the service is a high leg, so the single pole breakers in 25, 27, 29, and 31 don't make sense.

And spaces 26 & 28 have something similar to a breaker, but with no handle. It's labeled "Sub Feed" on the schedule, and it also has a factory label that warns about the terminals being live unless the panel is de-energized.

Spaces 14-16 is a 40A/2P breaker that is also labeled as a "Sub Feed".

So it seems like the 40A/2P might sub-feed phases A & C down to the bottom bus via. the device in 26 & 28.

Can anyone confirm that's what's going on here?
 

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No, I don't. I had no idea it was anything unusual while I was on site, and we didn't have an electrician on site either.

However, I realized that's exactly what the original drawings (1991) indicated - a panelboard with a 3 phase section above a 50A single phase section supplied by a 40/2 breaker.

I think that's gotta be what it is. I've just never seen one before where there wasn't an obvious break between the upper and lower buss. And there is another panel on the same site with the same basic configuration.
 
That panel can be built with thr bus connection fingers in a custom configuration. That panel appears to have the breaker spaces1-18 as 3-phase while spaces 19-42 are 1-phase only.
 
>Spaces 14-16 is a 40A/2P breaker that is also labeled as a "Sub Feed".
Is there a sub-panel somewhere?
 
robertd said:
>Spaces 14-16 is a 40A/2P breaker that is also labeled as a "Sub Feed".
Is there a sub-panel somewhere?
Click to expand...
14-16 and 26-28 were both labeled sub feeds. So I assumed it was sub-feeding two other panels.

But it is a split buss panel, so 14-16 supplies single phase down to 26-28, which powers the lower single phase section of the panel.

So, no, there aren't any sub panels.

First time I have ever seen anything like this.
 
I agree with Jim. I've seen just a few QO and other panels with special bus configuration for high-leg distribution. You get some 3ø, ABC spaces and the rest is bussed with only the non-high-legs.
 
Electromatic said:
I've seen just a few QO and other panels with special bus configuration
Click to expand...
The breakers are the QO family, but special bussing is not available in QO loadcenters you have to go to NQ panelboards like NQO, NQOB, or NQOD.
Most major panelboard manufacturers offered similar custome bussing.
 
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