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Old 10-08-2019, 02:00 AM   #21
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Originally Posted by HertzHound View Post
If the long 100amp breaker was always there with the wires looped around and down to feed the lower buss, and the short 100 amp breaker is now the Main for the whole panel, is it possible that someone came in and didn’t understand how a split buss panel works?

In other words a home inspector or inexperienced electrician saw the original set up and said “this is an illegal setup”. “It needs a main breaker”. Not realizing that the top breakers grouped together were all main service disconnects. By the way, is there anything marked on the cover as a main disconnect? Usually the “Main service disconnect” is a sticker on the breaker, and the circuit directory has the loads description. I only see a furnace sticker.
This is my guess too.

Most likely it was yet another incompetent home inspector who doesn't know anything about split-bus panels and panicked when he saw the wire from the meter connected directly on the main lugs.

But even as it is, it's not code-compliant, there's no hold-down on the new 100 amp main.
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Old 10-08-2019, 08:35 AM   #22
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My take is that this is a split bus panel that has been converted into a main breaker panel. Other than being a little confusing to the uninitiated, I think it's a good way to avoid ripping out what is otherwise a functional panel. All the split bus panels I've ever seen had no way to disconnect them besides pulling the meter and needed to be ripped out. This little workaround was a money saver.
To disconnect a split-bus panel, you throw the top breakers. I'm sure you know this, but work with me.

That's the point of a split-bus, as far as I understand. It complied with the 6-throw rule while not needing a large main breaker.

There would be 6 2-pole spaces at the top for 5 large loads and 1 60-100A+ breaker that feed the bottom part of the panel full of the branch circuits.

Installing a main breaker would serve no purpose other than being able to disconnect the small top bus. Seems odd to do.

I still think someone added those new #4 feeders/service conductors and felt they needed a smaller 100A breaker to protect them. Look at the size of that GEC, it's a #4 which would be for 200A. That, along with the giant 2" pipe that those #4 feeders are swinging in tells me that someone definitely lowered the feeder size to this panel.

We will never know. Just like I will never know why in 1950 someone took a piece of BX cable out of the left side of a 3 gang switchbox and brought it back into the right side, instead of just using a pigtail inside of the box

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Old 10-08-2019, 12:16 PM   #23
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I don't know if this was ever done in your area, but during the Medallion Home Era the LADWP used to provide 2 electric meters, one fed only the electric heating elements, and they charged you a lower rate. The bus was split so one side fed the furnace (more likely under plaster heating wires), water heater, range, dryer. The other circuits were supplied from the second meter. Many homes still have the same panel but the Utility pulled the meter years ago.

Not saying that this is necessarily the case here, but it's not completely unknown in the San Fernando Valley. Many tract homes built back in the 60's had them.
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Old 10-08-2019, 09:04 PM   #24
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What was common here was the water heater meter and special breaker. The meter was a time clock. It heated the water off peak. Not that we have peak rates for residential. They gave you a better rate. The line came in through the other meter as #10s and landed on a breaker that had a line and load. It had plastic feet and snapped onto the bus, but didn’t backfeed it. Maybe it came in as #8s. It’s been a long time since I’ve seen one. Most of the blanked off meter sockets are gone.

I zapped a co-worker once when I told him I pulled the meter. I wasn’t used to pulling the long time clock one.
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Old 10-08-2019, 11:56 PM   #25
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I don't know if this was ever done in your area, but during the Medallion Home Era the LADWP used to provide 2 electric meters, one fed only the electric heating elements, and they charged you a lower rate. The bus was split so one side fed the furnace (more likely under plaster heating wires), water heater, range, dryer. The other circuits were supplied from the second meter. Many homes still have the same panel but the Utility pulled the meter years ago.

Not saying that this is necessarily the case here, but it's not completely unknown in the San Fernando Valley. Many tract homes built back in the 60's had them.
True.

It was a 1960'- 'thing' when Pocos -- nationwide -- were seeing load growth of 7% a year. They needed customers to absorb the new capacity they were building. In that bygone age, the cost of juice kept DROPPING. That turned around in the mid-70s -- and every Poco ran away from such metering schemes.

However, on Oahu, the Poco still had the split rate scheme for Commercial accounts. I should know -- I had one.

On the economics, the reason for their scheme is that their gear sits largely idle at night. It REALLY IS cheaper for the Poco to have rock steady loads.
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Old 10-09-2019, 03:34 PM   #26
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I just wanted to jump in and thank everyone for the input - glad I could provide some nostalgia in return. My takeaways are:

1. Both 100amp breakers should be considered the main breaker... when I want to shut off electricity to the house, flip both.
2. Get an experienced electrician over to my house to assess this setup a bit closer.

Cheers
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Old 10-09-2019, 03:35 PM   #27
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I just wanted to jump in and thank everyone for the input - glad I could provide some nostalgia in return. My takeaways are:

1. Both 100amp breakers should be considered the main breaker... when I want to shut off electricity to the house, flip both.
2. Get an experienced electrician over to my house to assess this setup a bit closer.

Cheers
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Old 10-09-2019, 03:44 PM   #28
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Originally Posted by sl0flyer View Post
I just wanted to jump in and thank everyone for the input - glad I could provide some nostalgia in return. My takeaways are:

1. Both 100amp breakers should be considered the main breaker... when I want to shut off electricity to the house, flip both.
2. Get an experienced electrician over to my house to assess this setup a bit closer.

Cheers
Your panel is old enough that it is a good idea to replace it. A new panel with more spaces and the wiring cleaned up.

When talking to an electrician about it, mentioned the things we said here, about how it seems like someone reworked it and possibly lowered the ampacity down to 100A.

Maybe when he replaces the panel with a new one, he can replace those feeder conductors in the large conduit with larger feeders, giving you more than 100A.
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