ECN Forum Forums General Topics of the Trade General Discussion Area dimming lights

Your power company customer service will have to explain the rules they enforce. This is generally a published document, and may be available online. The rules vary widely from company to company, even localities within one company can vary.

The Los Angeles area that you are in will have an AHJ (Authority Having Jurisdiction). You will have to contact them for the permit and to have the work inspected. This is not changing a light bulb.

The wording of your questions causes me to suspect that if you are an electrician, as you claim in your ECN Profile, that you are very early in your education and experience. Perhaps one of your teachers can visit the site of your Zinsco panel.

Since you seem to be compelled to Do-It-Yourself, it is important to underscore that you are in the deep end of the pool. From your questions, it is also apparent that your Zinsco panel is in need of immediate attention. DIYers are responsible for educating themselves, and this includes contacting the proper authorities (the power company and the electrical inspector), pulling a permit and obeying the rules. Hire a local electrician to consult with you while examining your Zinsco panel. Record the conversation (with their permission). . .the amount a data you will receive will be large. No amount of note taking will suffice.

Lastly, review the first paragraphs of this site's [b]Rules, Policies and Disclaimers[/b]

Bjarney (and others): I remember seeing several of those Zinsco load centers about 30 years ago being installed in a church. It really was a weird bussing arrangement... three busses, covered with some type of thermoplastic insulation, I guess - black, red, and blue, that looked like it was literally woven into place. If memory serves me, the breaker jaws only had to be set in one position (they are removable in order to tap one or the other buss in a 1 phase setup, of course) in order to pick up each of the three phases.

The larger 3 phase Zinsco panels with the larger frame bolt-in breakers (in the case of this church, used as a MDP) seem to be better quality, but the smaller load centers with these cheesy plug-in Q frame breakers are really fraught with problems.

Mike (mamills)

Mike (mamills)

Mike — You nailed the description exactly. “Q-frame” was the one—I forgot about those triple-cheesy ‘swing-around’ bus clips. If aluminum bussing ever had a hope for switchgear, Zinsco did their level best as a prime example of how NEVER do it. They may have well been in cahoots with a few fire-insurance carriers for the extra premiums.

Another thing I remember from earlier decades was that they always had rock-bottom prices for their 200A meter/main/panelboard—they did it by always making the main breaker an added accessory, and it was a fine P-O-S in its own right. I think they led the pack in introducing one of the first plug-in 200A-frame breakers.


[This message has been edited by Bjarney (edited 10-02-2003).]

A number of years ago, a friend of mine called me because he was having problems with the lights in his house dimming/flickering, and even going out completely for a moment or two. When I went to his house, I was horrified to find a well-weathered Zinsco panel with a 150 amp plug-on main breaker (a really absurd idea, in my opinion), plus the usual numerous other smaller breakers. This 150 amp behemoth was hot to the touch, and generating the characteristic "bzzz" from the weak connection with the bussbars beneath. When I went to tap on it (the dead-front cover had long ago disappeared, I was told), the breaker popped off the busses into my hand, being supported only by the two hot legs coming from the meter! I could see how badly burned the buss bars were, and how the jaws on the breaker had lost their spring tension from the constant heating. My friend was not impressed when I told him what was going on, and that he was in the market for a new service panel. A day later, an excellent electrical contractor had replaced all this garbage with a brand new Square D panel, still working perfectly to this day.

drgnz23; I go along with the sound advice offered by electricAL. It appears that you have gotten all the "goody" out of your old Zinsco, and it's time to upgrade.

Mike (mamills)

[This message has been edited by mamills (edited 10-02-2003).]

Thank you guys for all the info...I wanted to get all the great knowledge that you guys could offer and i have suceeded . I appreciate it all

Bjarney's message caught my eye, and I wanted to add to it.


And, along the lines of Mamills' reply regarding the 3Ø Zinsco Bus:


I have dealt with quite a few of 3Ø Zinsco Subpanels with the mentioned type of Plug-On Bus Kit.
A "Weaved" and "Color-Coded" Bus is the best description that could be made!

The way the Breaker's termination stab(s) are positioned to terminate across opposite Phase Bus tabs was done by physically unscrewing the termination on the frame, then flipping it backwards from its current position.

Even more of an oddity was the 3Ø Split (or Dual) Bus type Subpanels. These had two seperate Bus Kits inside of one Enclosure (they were both the same type of "Weaved And Color-Coded" Bus Kits).
This resulted in a Zinsco Subpanel which had the similar "Left-Right" Breaker Spaces of other Panelboard types.

As known, the normal Zinsco layout has one "row" of breaker spaces - and if you number the circuits, they would go in step - "1", "2", "3", "4", etc. All on "One Side" (actually, there's only one row, so there is no real "Side" to reference!).

On the before mentioned Panel, the dual bus kits resulted in "Left: Odd, Right: Even" circuit numbering of spaces - similar to the "Normal" breaker space layouts of other brands.

(BTW: There were other makes of Panelboard Bus Kits with a single row setup. Square D's "XO" Panels are one such brand).

As to the rant about the Zinsco Plug-On Bus termination, I have thought the same as Bjarney!


Have dealt with SOOOOOOOO many fried terminations on misc. 225 Amp - 400 Amp sized Zinsco MCCB Frames, which were Plug-On.

Not all Manufacturers Plug-On frames are Immune! - Replaced lots of other brands too, just seemed to be a much higher percentage of Zinsco's (also, they were in Commercial Enviroments..the Zinscos and the others).

One particularly irritating event was during an Active Bank Branch remodel (Keep the Bank in full operation, remodel the entire building "around them").

Switch gear for both systems was Zinsco, and used Plug-On Busses.
(older area and building - services fed from a 4 wire Delta. One 3Ø service section, one 1Ø service section)

1Ø Gear Section had two - 200/2 frames, along with a few smaller ones. The 200/2's fed heavily loaded Subpanels.

During the preliminary stages of the remodel, odd behavior was observed in the operation of the existing Indoor Lighting - Transient dimming, fixtures going off then on; along with Motors running sluggish (bathroom exhaust fans).
Contactors of the EMS Control Panel I had installed previously were also effected - and were randomly opening and closing rapidly.

All these loads were on the same Subpanel.

Since we needed to keep the Branch in full operation (we worked the crucial remodel stuff during the branches "Off-Hours"...AKA Night Work!), and the problem had become increasingly worse over a 4 day period, it was agreed that I would shoot trouble on this ASAP.

Checked the entire Subpanel, found nothing wrong! (Subpanels just happened to be right next to the gear, too!).
Suddenly as I was replacing the Dead-Front, the lights started freaking out again - and the Subfeed Breaker was buzzing like crazy!

A simple Inspection of the breaker revealed the problem!
Next Evening after the branch was closed, I replaced the breaker + cleaned up the bus kit.
When I tried to unloosen the lugs for the Subfeed Conductors, the entire frame disintegrated in front of me!

Had things back up in about 1½ Hours.
No problems on that Subpanel after that.

Next one to fail was the Subpanel with the Computer Equipment on it!!!

About 10 days after the first scenario was rectified, it hit again - this time the problem was causing a greater deal of bad stuff!

Again, transient losses of power were experienced on...of course, ½ the computers each time! The server equipment was on UPS, which the power loss alarm could be heard once in a while.

The other affected Subfeed frame was located at the Upper Right of the bus kit, and this one was at the Lower Left.

I troubleshot the situation - except this time, began at the Gear.
Sure enough, the exact same thing was happening here, and the frame also disintegrated upon loosening the lugs.

Prior to final commissioning, both bus kits on both Gear sections were replaced, along with the remaining existing frames. (Bank's Const. & Dev. staff weren't hesitant in the least to authorize this C/O!!!)
They had sent numerous techs out prior to the remodel to fix the problem (staff calls for service), along with sending out IBM to verify things on the machines.

Can only imagine the money lossed on this!
Losses from the service calls, the IBM support calls, the loss of data, all that stuff!

Having dealt with these types of situations really drives home the idea of NOT using Plug-On devices in Designing of Electrical Systems for Commercial Enviroments!!!

Hope this story is enlightening and interresting!

Scott35

Scott — That is a very lucid account. To hear about loss of critical business data caused by cheap, sleazeball power systems is so sad. ;-) ;-) ;-) ;-) ;-)

When institutional and commercial buildings are fitted with gear that is substandard even for a housing tract, all the “We just cannot stand for this!” junior-assistant-trainee office manager or snot-nosed MBA whining is mildly entertaining.

First. Aluminum has no memory. Tighten the neutral lug as it gets loose...DIM !! and second.. Yard out that old zinsco panel and re-wire the house up to code ! You will feel alot safer and be able to sleep at night ! Smoke det. in each room, ect.. ya know !!! Electrical services dont cost much and can save your life ! whyrag

This post reminds me of an installation I did years ago as an apprentice.

A pottery person had two kilns on an old service, and kept blowing fuses.
She had a 100A service, with two 30A kilns on fused disconnects. She knew she could only run one kiln at a time, but would blow fuses when the elements shorted during an explosion in a kiln.

She wanted breakers instead of fuses. They didn't make them anymore for her panel. She couldn't afford a main panel replacement. We couldn't find a 60A breaker for a sub-panel. We did find a 60A main breaker that would fit her panel. It was a screw-in as opposed to push-in.
We talked to the local inspector, called the national onsite approval people, drilled and tapped her existing bus bars, and installed the 60A to feed a sub-panel.
All authorities agreed and passed it because they estimated her 'old' bus bars capable of 300A.