Thread: Zinsco panel. Split bar?

Is this a split bus bar. Feeders come in from meter, no disconnect. Disregard the tank.

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I've never seen one of those before ...

That's not a split bus panel in the normal sense in that the 'mains' part of the panel is limited to 6 breakers and one of those 'mains' feeds the other bus section - that one is more of a 'double bus' panel ... weird, never saw one before.

Was the cover factory looking? If not, may have been someone's idea of taking an oversize enclosure and putting to panelboard interiors in it.

From what I can see the left bar is the mains and one of those feeds the right side. New to me but looks like it is just a slightly different layout from the traditional split buss panel.

Copy the never seen one of those before. Zinco's version of the "double wide". Based on the wires and C/Bs I can see; the entire right side is a, ( split ), bus. Looks to be fed by a C/B in the "main" section. There are already the maximum six allowed disconnects in the left side, but plenty of room for more ( ? ). As best I can determine, it's code compliant for the vintage, ( until another C/B is added to that left / main disconnect side ). Very unique !

Never have seen that in a 1Ø panel but the double row was common in Zinsco 3Ø panels for plug-in breakers, which are a weird beast all by themselves. 3Ø bolt-on Zinsco panelboards are "normal" in the way they are configured.

Edit: If you look closely at the picture, there are a set smaller lugs adjacent to the main lugs, I suspect there was a factory jumper installed to the right side section. It may even be old enough to have copper bus.

I thought is was just me, I told the buyer I had never seen one like this before.

Here is the cover

There is a 70amp breaker on the left side which feeds the right bar. The left bar is fed by the feeders coming in from the meter, there is no service. So you cant shut off the power with six or fewer. I am uning the usual reporting for zinso but would you identify the split bus as a hazard.

Double trouble!

I too, have never seen anything like that. But as inspectors, we get an easy out reporting it. Just write something like Zinsco panels have documented problems. Current industry recommendation is to replace the panel. Have a licensed electrician evaluate and/or replace the panel as necessary.

But for our edification as inspectors, knowing more about a beast like that is certainly worthwhile.

The restrictions on the labeled equipment likely prohibit use of the half-size 2-pole minis on the externally supplied Mains side when employed as service equipment (i.e. full-size only often by cat. number or type breakers). Apparently of a non-CTL vintage.

Non MCB, or six or fewer, is not an issue of issue since a its main power feeder-supplied and not a "service" supplied panel (as you said). Six are present (the five 2-P 120/240 need to be tied plus the lighting main).

Not unusual to have a back fed breaker feeding a "lighting mains" on a split bus. Its not the first vintage panel pictured on the forum to use conductors to the sub-buss on a split bus panel, nor the first zinsco.

Check the fine print on the labeling - the "stab rating" (max) for the "main" side likely limited (usually at the vintage to 60 A). There is also likely "max" as in cumulative total ratings (not load calculations) for the breakers attached to each set of busses.

Side-by-side split buss (often installed side-ways in vintage installations even with OFF "up" on half) also not unusual.

Sadly, the remodel of the area nixed any "grandfather" status - as the installation of the new cabinets which now encroach on the equipment space. Rip out the cabinets or move the location for the replacement panel. Installing cabinets in a new location might not have required permit - but violating the electrical code then and at the time of the newer cabinet's installation in a new, not previously occupied by cabinetry, location (note cabinet door swing direction) violated the electricl code at the time of (the cabinet's) installation. Hopefully the washer or electric dryer hookups aren't also immediately below the new wall cabinet (further encroaching - when installed - the equipment access zone) in what I'm guessing is the newly 'updated' laundry area.

Yeah, crazy looking. Not seen one before. Doesn't appear to qualify as a split-bus since the installation looks like it would allow more than six double pole breakers on the "main" side. If so, it should have been installed with a main disconnecting means. This looks like an expandable panelboard which allows the installer to put in a single panelboard or expand it to accept two. All split-bus panels I have seen are arranged with the six mains on top. One of the six feeds the bottom bus with the lower capacity breakers on the bottom.

Here is my canned comment for Zinsco Panels or Sylvania's with Zinsco breakers.

This property has a Zinsco brand main service panel and circuit breakers. These panels and circuit breakers are known to have a variety of problems including:

*Buss bars possibly made from aluminum alloy and are more likely to oxidize and corrode
*Breakers that don't trip under normal overload conditions
*Breakers that appear to be tripped when they're not

You should be aware that these panels do not offer the level of overcurrent and fire protection provided by most other electrical panels and circuit breakers. Becasue of this we recommend that the panel be updated and replaced.