Unsure if licensed electrician correctly wired old Zinsco 100-amp panel to new Siemens 200-amp subpanel

Question

Our 1,572 sq. ft., 1972-built home in San Diego has a 100-amp Zinsco panel. We just learned that Zinsco busses and circuits are a known fire hazard. We talked to 4 licensed electrical companies, had two out to the house, and hired one. We made it VERY clear that the objective of our project was to get rid of the Zinsco fire hazard. The company that we hired said they would install a 100-amp subpanel and leave the Zinsco out of it.

Instead of a 100-amp unit, they installed a Siemens 200A SN Series Main Breaker Load Center, catalog #: SNW2040B1200. We do not know why. They put all new circuits in the new Siemens except that they did not install the Main 100-amp breaker in the Siemens. Those Main "slots" are empty and covered with "face plates".

In the old 100-amp Zinsco, they removed all circuits except for the 100-amp Main. They then added another, old-looking, Zinsco 100-amp circuit to the Zinsco, which they supplied, for a total of two 100-amp Mains in that Zinsco 100-amp panel. So their finished installation goes from the utility to the Zinsco, through a long conduit to the Siemens, and into our home.

We were distressed to find that the Zinsco was still part of the wiring because of the Zinsco fire hazard, which we had communicated to them. They repeatedly told us that the Zinsco was no longer a fire hazard because the Zinsco panel was there "only there now to power the Siemens subpanel". We do not believe that is true.

I online chatted with Siemens. The Siemens rep said, "I'm on board with removing Zinsco from the wiring, and can recommend a 200A enclosed circuit breaker or small breaker box to feed your panel, but definitely would have questions about the need for the feeder breaker to begin with - why was the upstream Zinsco product not also removed? Something seems 'off' about this to say the least, I'm just not sure where Zinsco products fit into this setup upstream if they are intended to be replaced entirely."

The city inspection is on Thursday, June 27. The inspector, the electrician, and we will be there for it. We are hoping to have a better idea if they did not did not wire and install correctly and safely.

We would greatly appreciate any input on the above as well as any questions that you think we should ask the inspector and the electrician.

Answer 1

They were lazy/cheap. The normal process would be to call this a "heavy up". That would typically involve:

• Replacing the feed from utility to meter with 200A wire.
• Replacing the meter box with a modern one approved by the utility. It would likely use the same actual meter (because most utilities replaced the original meters with smart meters years ago) but might, depending on local code, require an external disconnect, which usually makes the meter main the actual main panel.
• Replace the feed from the meter to the panel with 200A wire.
• Replace the Zinsco panel with a new 200A panel in roughly the same location.

Doing this has several advantages:

• More power available
• Zinsco totally removed
• Branch circuits in the same location as before so they don't need to be extended
• Branch circuits considered "the same as before" so AFCI and GFCI retrofit not required

They were correct to install a 200A panel - that's future proofing even if limited to 100A now.

Quickest fix is a 100A main breaker on the Siemens panel and replace the Zinsco with a simple junction between the 100A feeds. But inspector may want that 100A breaker near the meter, as is normally done.

Answer 2

It sounds like this is step 1 of a 2-step process.

First step, install a 200A bus rating panel to be the new "panel with all your breakers". Move all your circuits to that. Temporarily feed it with the old infrastructure and main breaker.

Second step, replace meter pan with a "meter-main" or "ranch/trailer panel" with a 200A breaker. Come off that with 4/0 wire to the 200A panel previously installed. This requires the power company to come out and remove the service drop. Alternatively, a new mast/weatherhead could be built right next to the existing one.

So I see where their "big picture plan" is, but obviously they've been doing a just terrible job communicating that plan with you.

And I think they were reluctant to do part 2 because that step involves interacting with the utility, who can be a stickler on permits and inspections.

Instead of a 100-amp unit, they installed a Siemens 200A SN Series Main Breaker Load Center, catalog #: SNW2040B1200. We do not know why.

It's like 130 MPH tires on a car only capable of 105. The subpanel breaker and bus rating don't matter, so long as they are >= the feeder wire. However, their choice was a wise use of your money, since it gives you an easy upgrade path to 200A service later.

I just find the work they did to be suspiciously specific, and they seem to be up to something which makes sense, but clearly have not communicated well with you.