GTE Sylvania Zinsco breaker & panel identification:

How to Identify Zinsco-Sylvania & GTE-Sylvania-Zinsco Electrical Panels and Circuit Breakers.

Here we provide text, labels, and equipment photographs used to help identify Zinsco and GTE-Sylvania-Zinsco electrical panels and circuit breakers, and we include photographs of a Zinsco look alike marketed by Kearney.

Discussed: GTE-Sylvania-Zinsco Electrical Panels that used Zinsco circuit breakers and bus design & may involve similar electrical panel failures and safety concerns as Zinsco.

How to Identify GTE-Sylvania-Zinsco Electrical Panels and Circuit Breakers

This website discusses the electrical, fire, and shock hazards associated with Zinsco electrical components, circuit breakers, electrical panels, including certain Sylvania electrical panels and breakers which are in fact of the same product design and origin.

[Click to enlarge any image]

Article Contents

• IDENTIFY GTE SYLVANIA-ZINSCO PANELS
• GTE SYLVANIA ZINSCO ID PHOTOS
• GTE SYLVANIA ZINSCO PANEL LABELS
• GTE SYLVANIA ZINSCO PANEL MODELS & CIRCUIT BREAKER CODES
• GTE SYLVANIA ZINSCO ARC FLASH FAILURE REPORT
• CEB, COMMANDER, GTE, SYLVANIA PANEL BRAND RELATIONSHIPS

GTE-Sylvania / Zinsco Panel Identification Pictures

Below is a close-up of the bus connection end of a classic Zinsco circuit breaker - showing the difference between these devices.

Zinsco electrical panels were distributed in the United States, primarily in the Western states.

Photo of a recent GTE Sylvania Zinsco circuit breaker burn up courtesy of Jeff Weissman.

Some Sylvania brand electrical panels are essentially a "Zinsco in Sylvania's clothing".

The panel labels may identify it as "Sylvania", Sylvania-Zinsco, or GTE-Sylvania-Zinsco.

But the circuit breaker colors and other external details permit the inspector to identify the problem Zinsco-design electrical panel bus and circuit breaker materials.

Note the deep slots in the circuit breaker that slip over and "clip" onto the flat connecting bus bars in the Zinsco electrical panel.

Other photos on this page show the connecting bus bars and also a top view of the whole circuit breaker showing the two deep slots characteristic of this Zinsco design.

Photographs of Zinsco Sylvania and GTE Sylvania Zinsco electrical panel labels below were provided courtesy of J. P. Simmons.

Watch out: do NOT try to open up your panel nor to remove circuit breakers yourself. There is live voltage in the panel interior - you could be shocked or killed. Never insert any tool nor your fingers into the interior of an electrical panel.

Electrical panel interior access should be by a licensed and trained electrician.

An expert who opens the electrical panel or performs further disassembly (DANGEROUS STEP) can further identify the characteristic circuit breaker details but the circuit breaker toggle switch colors and unique labels should be sufficient for most inspectors and owners to identify this equipment.

• Sylvania Zinsco Main Panel, note the blue and silver foil "Sylvania" label
• Sylvania Zinsco Main Panel, main breaker and Sylvania label
• Sylvania Zinsco Main Panel, close up of the blue and silver Sylvania label
• Sylvania Zinsco Main Panel, Sylvania label and pale green double pole breaker
• Sylvania Zinsco Main Panel, close up of the blue and silver Sylvania label
• Sylvania Zinsco Main Panel, double pole green Zinsco circuit breaker in a Sylvania-labeled electric panel
• Sylvania Zinsco

Zinsco-Sylvania Electrical Panels Labels

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Some Sylvania brand electrical panels are essentially a "Zinsco in Sylvania's clothing".

The panel labels may identify it as "Sylvania", Sylvania-Zinsco, or GTE-Sylvania-Zinsco, but the circuit breaker colors and other external details permit the inspector to identify the problem Zinsco-design electrical panel bus and circuit breaker materials.

Photographs of Zinsco Sylvania and GTE Sylvania Zinsco electrical panel labels courtesy of J. P. Simmons.

An expert who opens the electrical panel or performs further disassembly (DANGER) can further identify the characteristic circuit breaker details but the circuit breaker toggle switch colors and unique labels should be sufficient for most inspectors and owners to identify this equipment.

Readers should also

see IDENTIFY ZINSCO SYLVANIA METER BASE and

see GTE-SYLVANIA-ZINSCO FAILURE MECHANISM,

as well as ZINSCO FAILURE REPORTS.

CONTACT US with field reports and photos. We are pleased to credit and link-to contributors.

Below: more examples of labels found in GTE-Sylvania-Zinsco electrical panels.

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GTE Sylvania Zinsco Electric Panel Model Number & Circuit Breaker Codes

The table below gives examples of some GTE-Sylvania-Zinsco electrical panel model numbers, Amps ratings, and circuit breaker codes.

Notes to the table above

Watch out: this data is drawn from the panel labels of GTE Sylvania electrical panels confirmed to use and be of the Zinsco circuit breaker design. But it is by no means an exhaustive listing. Still, if your electrical panel uses the circuit breakers listed here it may be a Zinsco design. Proceed to complete the identification your panel by having its main bus design examined by your electrician. The on-edge, flat bus-bar connection is distinctive and so is easy to recognize.

Relationship among CEB, Commander, GTE, Sylvania Electrical Panel Brands

Be sure to also read HISTORY of ZINSCO ELECTRICAL PANELS

Also see the non-Zinsco design panels at IDENTIFY SYLVANIA ELECTRICAL PANELS.

The following remarks from a licensed electrician were provided to us courtesy of Al Carson, Carson Dunlop Associates, a Toronto home inspection and home inspection education firm.

No-Trip Complaints involving Sylvania, GTE-Sylvania, Older Commander & CEB Electrical Panels

Pending research citations the following quote is opinion:

The Sylvania, GTE Sylvania, older Commander and CEB are really the same panel and it is was a very popular panel in the 70’s and 80’s. They have a reputation as the breaker which doesn’t trip. I have personally experienced it over 20 times for overcurrent situations and about 5 times in fault current situations.

It is also the panel which had several 100 ampere main breaker fails which led to fires. As a consequence of this, in Ontario we had to mount drywall behind panels for years. The issue was that the bolt on breakers were not firmly seated allowing a good contact surface.

This was because the threads on the bus bar were poorly manufactured and the electricians installing them would tighten it down, but not realize that the bolt was carrying the main current due to the gap

. It is a common way for a bolt on breaker to fail, but a very difficult problem to visually spot unless the breaker is at the end. Infra-red scanning on a loaded breaker would be the best way to spot it. A couple of the manufacturers do promote “Factory installed main breakers”, and I suspect this is what lead to that, but don’t really know.

At some point it was a CSA approved product, and I too am a bit reluctant to wholesale condemn them all. I am always very careful what I say as many people quickly jump to conclusions that I am “upselling” or “Fear marketing”. But I would rather live in a house full of knob and tube than one of these panels.

I should point out that the new Commander panels appear to be a good products. I should also point out that the 200 ampere mains are mounted differently and as far as I am aware had no problems like this. ... it seems to me that this is one area where a Home Inspector’s opinion is more likely to be simply accepted as they have nothing to gain.

I have never heard of Kearney [see IDENTIFY KEARNEY PANELS]

and was not aware that Zinsco made combination residential panels

[see ZINSCO SYLVANIA ELECTRICAL PANELS].

Although sometimes brand names change at the border. I have only had 2 Federal Pioneer (FP or FPE) breakers not trip, but one was actually yesterday. One of my staff accidentally cut the wrong wire. Lots of sparks and a hole the size of your pinky in his pliers and neither the branch nor the main opened under a few second long fault. We are changing the panel Monday.

It appears to be less than 10 years old, but with some older breakers in it….still the main should have tripped. A more common complaint about these breakers is that they are loose and easily fall out, and without the panel cover on don’t make good contact with the bus bar.

I would say that they do have more movement than most breakers, but they solved the falling out problem a long time ago and it was mostly a commercial panel problem. They have stopped making Federal Panels anyway.

I’m not sure what the best policy is here, but this much is true:

• Breaker technology is constantly improving and new is better than old
• Electricians are reluctant to “approve” installations by others or any old products. Most would encourage home owners to change the panel.
• To unseat every breaker and check it and redo every other connection would likely cost about $300 - $400 less than a new panel installation which would come with a warranty.
• When a female thread is poorly manufactured it is almost always due to excessive wear on the threading tool during manufacture.
  
  Almost always a tap can quickly be run through this hole and the problem solved. But when the female thread is located on a bus bar with insufficient space to run a tapered tap tool through it is tough to fix and in some panels rivets are used to mount the bus bar.
  
  I had a full panel years ago, and had this problem on the very last breaker. I ended up deliberately breaking the tap tool as a desperate measure at the end of a long day. Since then I have tried to always use push on breakers unless it is an industrial or vibratory environment.

I should simply say yes change these panels, but I know for sure someone will challenge that and it would be better to have reasons. I’m copying other Langstaff & Sloan Inc. staff in case they have any additional thoughts.

- Anonymous (pending author wish to be identified) to A.C. to D.F. 20 March 2015

Watch out: removing and replacing circuit breakers or "exercising" them by turning them on and off can in some cases actually increase the risk of a future failure because of scoring of a plated panel bus bar or because some breaker brands such as FPE show an increased failure to trip after being switched on and off.

Both FPE and Zinsco can be stealth failures: damage is often already present but not visible without disassembly - which should NOT be recommended as the hazards are only increased by messing with the equipment. - Editor

Editorial Opinion on the above

There is among electricians an endemic problem common to everyone working in contracting: an unfamiliarity with solid technical research sometimes leads folks to assert that nothing was wrong with product X except that it was the nature of the times in which it was made or installed.

Sometimes that's true. But other times not. Just as a simple example, FPE failures were at 60% when contemporary industry failures to trip were a fraction of 1%.

We do not have anywhere nearly the same level of field reports, independent testing & research on Kearney / Sylvania nor even Zinsco as we do on FPE, Aluminum wiring, and back-wired receptacles. Some of these such as FPE involved outright fraud by people who knew perfectly well that the product did not perform properly.

We have published articles on these other panels in part to solicit field reports & research information. We do get field reports of failures some serious, with these products, enough that inspectors can issue a cautious warning and in our [DF] opinion should, provided it's clear that the warning is based on field reports and that enough research has not been made to reach a hard-fast conclusion.

See GTE-SYLVANIA-ZINSCO FAILURE MECHANISM

But watch out: there are surely plenty of other GTE panels that are a completely different design and don't have the GTE-Sylvania panel issues.

Also it was interesting ... that a New York Electrical Engineer performing independent tests on samples of used circuit breakers of a variety of brands found in very preliminary testing was that there were a few other contemporary panel/breaker products that appeared to have high (compared with overall industry) no-trip rates.

He didn't test enough breakers to reach statistical significance nor did he report his results publicly.

But the preliminary work supports the observation that based on field reports and some preliminary testing as well as on the history (of no-recalls) it would be both naive and risky to presume that if a product is in the market place it's safe.

Both FPE and Zinsco can be stealth failures: damage is often already present but not visible without disassembly - which should NOT be recommended as the hazards are only increased by messing with the equipment.

and I am watching carefully Challenger as well as the others you name.

And I would give strong consideration to replacing any panel that had

1. Aluminum bus bars
2. Plated aluminum bus bars that get gouged-through when a breaker is inserted (mounting a breaker cuts through the plating and we see corrosion, overheats, failures)
3. Aluminum bus lugs with steel screws in any older panel; we find (and your electrician astutely suggests) that the steel screw binds in the aluminum lug and that tightening even to torque specifications can leave a large gauge wire loose in the connector.
   
   I [DF] have personally investigated a few such cases that led to serious hazards.
   
   See LOST NEUTRAL SHOCKS HOMEOWNER

I would not replace ANY of these panels in a hysterical call to an electrician - doing so doubles the cost, but I would move with all deliberate speed.

For people who are too poor to make their homes safer by replacing questionable electrical equipment, we suggest some initial or temporary hazard reduction measures:

1. working properly located smoke detectors
2. mobile home doors that open properly - all buildings need safe functional fire exit passages
3. Turning off any strangely behaving circuits (flickering lights) with the caveat than in an FP/FPE case, "turning off" may actually leave the circuit on, as the breaker may not switch off internally.

Reader Question: Are These Sylvania Electrical Panels the Zinsco Type? What are the Sylvania-Zinsco Points of Identification

I was reading information on your website about Zinsco panels but I can't determine if my main panel and sub-panel inside the house are the affected panels. Are you able to determine this from the attached pictures?

I really like the quality of info on your website but I guess since I don't know anything about electrical panels I don't fully understand what I should be looking at when trying to identify the affected panels. Victor [by private email] 10 September 2015

Reply: Red Arrows Indicate Points of Zinsco Identification in Your Sylvania Electrical Panel Photos

Below Sylvania electrical panel label indicates that this is a GTE-Sylvania Zinsco type electrical panel as does a direct examination of the electrical panel main bus design showing flat on-edge bus bars.

[Click to enlarge any image]

Above: Sylvania electrical panel Catalog No. ML12(12-24)C (Indoor) - Mod. 2, Type 1 Enclosure, 125A Max..

This Zinsco-Sylvania-GTE electrical panel label specifies

Use GTE Sylvania Circuit Breakers Type Q, QC, R38, RC38,and HRGF.

Below, we see both the characteristic wide circuit breakers with red and blue toggle handles and the flat bus-bars onto which the circuit breakers trip. Arrows point to points of identification characteristic of Zinsco breakers. Clockwise from upper left:

• Red and blue breaker switches with visible colored base
• Oblong opening at wire connection terminal
• Flat electrical panel bus bars in parallel fitting into two slots on each breaker
• Oblong opening in plastic receiver of bus bar ends

Compare these to other circuit breakers or to other Zinsco breakers in this article series. The details to which we point are unique to Zinsco.

Below at left:

• Vertical arrows point to the flat electrical panel bus bars of a Zinsco electrical panel
• Horizontal arrows point to the two long slots that appear in the Zinsco circuit breaker. Often you will see evidence of arcing or burning at this location.

Below right: a badly faded Sylvania electrical panel sticker.

Below: a combination Electrical Meter Base and Outdoor Zinsco Electrical Panel:

note the same flat electrical panel bus bars (to which the breakers clip) and identical circuit breakers as those detailed above.

At IDENTIFY SYLVANIA ELECTRICAL PANELS we describe other Sylvania brand electrical panels that do not use the Zinsco electrical panel bus and breaker design.

Field Failure Report: Arc-Flash Damage in a GTE Sylvania Zinsco-type Electrical Panel

Reader reports arc flash burn & asks about GTE/Sylvania panel recall

I'm dealing with this problem in my home currently, I have both my HVAC and an electrician here. It turns out as I'm reading your article, you cite someone named James Simmons from Mr Electric.

Completely by coincidence I happen to have gotten my hands on a Mr. Electric electrician today. He was recommended to me by a friend who's in contracting locally. He's doing a great job.

He did not know about the Zinsco/Sylvania problem. I discovered it by coincidence doing a search on line during the eight hours they've been here so far.

There were problems found with our air handlers and they were wondering if that is what caused this Ark. Once I found your website we started to take a different path.

If you're interested in more information or details please let me know.

Thank you for your information. Also is there a place where I can research to find out if my panels were officially recalled? - Anonymous by private email, 2017/02/16

Reply:

Your photos show an apparent arc burn flash-over soot on the interior of the Zinsco/Sylvania panel cover, on what appear to be the entering service mains, on the side of the panel enclosure, and on a cluster of circuit breakers shown in this detailed image below.

Without more investigation of the breakers, panel bus, and circuit involved one cannot say for certain if this arc-flash damage was due to a defect in the circuit breaker, panel bus, connections, or some other issue.

OPINION: a look by your electrician at the condition of the circuit breaker-to-bus connection might show the same arcing and burning illustrated above in this article. That would argue for an occurrence of the bus-connector defects and hazards we've described.

In any case, I would replace this electrical panel.

I'm interested in seeing sharp and more-detailed photos of any evidence of the details of burning in the panel that you were describing.

That would be useful additional information to document.

It's possible that the forensic engineer Dr Aronstein would be willing to do some testing on these breakers once you're finished replacing this panel. I'll check with him.

There is no and was no GTE-Sylvania Zinsco electrical panel recall that would help you out with replacement costs.

 

Question: is this an unsafe Zinsco electrical panel?

2020/04/22 Ben said:

Hi this seems to be a really helpful site, thanks!

I am also wondering if my box is one of the hazardous ones. I'll attach a picture of the Sylvania sticker and also another one of the whole box.

Thanks so much, this is a great service you are providing!

Reply: - colored circuit breakers characteristic of Zinsco not seen in this unusual Sylvania electrical panel

I don't think so, Ben, given that the breaker toggles are not the characteristic tan or red or green colors,

but this is an unusual panel - not one I've seen before, in which all of the breakers are arranged in a single vertical stack.

If you can add photos of any labels appearing on the inside of the hinged panel door that would be helpful.

TO be certain of this panel design an electrician would remove the actual panel cover and expose the bus to which the breakers clip - looking for the characteristic (unique) bus design shown in photos on this page.

Reader follow-up:

Again you guys are great for helping out! REally appreciate your feedback
(wow, and quick too!)

Well I am in the middle of Working From Home in this crazy time! Will snap
more pix when I can drag myself away from computer.

Thanks again *and* in advance after I get more pix!

Ok got pix of the stickers -- will add the images.

Thanks again! Interesting detective-work ....

Moderator reply: this is an unsafe Zinsco electrical panel

Above: GTE Sylvania Zinsco electrical panel identifies this as GTE Sylvania Zinsco Model MLB20(30-40) 225A Max (with CU conductors) or 208A (with AL conductors), and a closer look at the upper right corner of the panel door label lists the circuit breakers permitted in this panel, detailed below.

Good Going, Ben

I sit CORRECTED.

The panel label specifically says to use Zinsco circuit breakers.

This GTE Sylvania Zinsco panel label states

• Use Zinsco circuit breakers type Q, Qc, QCN, Q24, Cat. No. Q242... [illegible] and continues, stating
• Use Z I N S C O QFP24 Circuit breaker LK-15, LK-15 or LK-22 for MAINS as indicated. Rating with LK-15 150 Amps, LK22 225 AMP.

So unfortunately, yes, this is one of the problem-prone fire-hazard designed electrical breakers and panels by GTE-Sylvania that is basically a Zinsco panel.

You should replace it.

I expect your electrician to be able to confirm the design by removing the panel cover and noting the classic Zinsco bus details.

Can you tell us

The age of your home ?

I see it's in Fairfax Virginia (my home for many years) and I'm guessing from the electrical inspector's tag that the home or at least the panel is from 1976.

Reader follow-up:

Yes, this house is indeed in Fairfax. It is from 1975. I think that is
fairly common around here.

Ok, I see, the panel label has the language you spotted. Guess I had better

talk to our electrical contractor :(

Thanks again for your help and eagle eyes! For a minute I thought we were
good! At least I am aware though.

Really appreciate your help!

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2022-08-28 by InspectApedia (Editor) - Sylvania panel seems to have Zinsco type breakers

@Rosario Roman,

Those colored breakers look like the Zinsco type.

The word "Zinsco" may not appear on the panel or breakers.

On 2022-08-28 by Rosario Roman

I want to buy an interruptor for my circuit breaker box have the number 15 and the the box name is silvania have

On 2022-05-27 by InspectApedia-911 (mod) - Zinsco breakers are distinctive even if Zinsco is not printed anywhere on them

@Jeremy,

Those colored breakers look like the Zinsco type.

Those vertical or "on-edge" bars are an un-mistakable Zinsco design feature, as you'll see on the page above.

The word "Zinsco" may not appear on the panel or breakers.

On 2022-05-27 by Jeremy

Hello, I’m looking to install solar. I’ve had 4 quotes. One guy didn’t ask to see my panel. The second guy looked at the beaker switches and the “Sylvania GTE” label and said I need to replace it. The other 2 guys each sent pictures to a “colleague” who replied and said the panel does NOT have to be replaced.

I don’t see the words “Zinsco” anywhere, but I removed the internal switch cover and I appear to have the “vertical” bus bars.

On 2022-03-25 by Inspectapedia Com Moderator - what does a 'failed' inspection mean?

@Joyce todd,

Sure, this won't be difficult:

1. OPINION: First: "failed" by an inspector sounds a bit unprofessional to me. Home inspectors don't, can't, or have no business passing or failing buildings. The inspector's job is to find and report things that are unsafe, causing rapid expensive damage, or that don't work. So "fail" is a bit over the top. Certainly considering the price of homes, the cost of a new main panel switch, even if that were recommended, is hardly a fraction of one percent of the home's value, so would, in no rational mind, be a reason for someone not to buy a home.


2. Objective data is needed: Why was the main switch "failed" by the inspector? Rust, damage, overheating? Perhaps - as I see some rust on the panel cover. Did he or she actually remove the cover and inspect the panel interior as is required by home inspection standards?

In short, the "failed" is improper reporting. What's needed is a clear statement of what's wrong.

3. SO perhaps what the inspector found as "wrong" or "unsafe" is that the main breaker is a Sylvania-ZINSCO design - an unsafe circuit breaker that is prone to burn-ups and failure to trip: an important safety hazard.

It's trivially easy to identify the Zinsco design - and not all Sylvania Panels are of the Zinsco type. The breaker design is distinctive, can be easily shown to you by your electrician who removes the panel cover to show the bus and breaker design details.

Details of what Zinsco's look like are at

IDENTIFY GTE SYLVANIA-ZINSCO PANELS

and at

IDENTIFY ZINSCO SYLVANIA METER BASE

On 2022-03-25 by Joyce todd

I’m trying to sell my home, inside electrical box and breakers are 4 yrs old and fine, but inspector failed me because my outside box is a Sylvania 390-205-09, he says it’s recalled and must be replaced, my electrician disagrees with him, so he won’t do it, help! Please advise or give me some documentation, thanks

On 2022-03-23 by Inspectapedia Com Moderator

@LisaT,

Looks like Zinsco in your photo.

Please read the article and see my earlier post so as to confirm and make a reliable determination.

On 2022-03-23 by LisaT

@Inspectapedia Com Moderator,

So you aren't able to tell from this photo? Thanks!

On 2022-03-23 by Inspectapedia Com Moderator - How do I know if this is actually Sylvania or if it's Zinsco?

@LisaT,

The article above gives details.
Please take a look.

The breaker design is distinctive.

Your electrician can open the panel and show you the side view of a breaker.

The toggle switch colors are also indicative.

On 2022-03-23 by LisaT

How do I know if this is actually Sylvania or if it's Zinsco?

On 2021-12-28 by Inspectapedia Com Moderator

@Fraser Westerfield,

Apologies but I've not found an authoritative Sylvania panel model number list that works to answer the Zinsco question.

However you can easily identify the Zinsco design as we explain in the article above on this page. Do take a look and let me know if that leaves you with any questions or suggestions.

On 2021-12-28 by Fraser Westerfield

Is Sylvania panel model MTMB20(20-40)F; MTMB20(20-40)S one of the Sylvania-Zinsco models that needs to be replaced?

On 2021-08-31 by inspectapedia.com.moderator (mod)

@Cindy,

those circuit breakers are quite distinctive as Zinsco; your electrician can confirm, without the slightest doubt, by removing the panel cover to show the circuit breaker design and the panel bus-bars to which the breakers connect. Example photos are above on this page.

On 2021-08-31 by Cindy

Hello - I bought my home new in 1983. I've never had any issues with my breaker box. My home had a fire (from attic wiring) in 1997, and after the rebuild, including ALL inspections including electrical, I moved back in.

Now, I need to have a Whole Home Surge protector installed & an electrician told me this is a SYLVANIA-ZINSCO PANEL based on pics, and it needs to be replaced. Estimated at $2,200.

Could you please let me know if this is in fact the Zinsco panel that is dangerous? I'm attaching pics. Thank you in advance for any help you can provide.

Question: verify the bus rating of this Sylvania-GTE Electrical Panel?

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I would like to verify the bus rating of my house panel the only label that I have is what is attached in the photos
Hopefully you can help

The reason I need to verify the buss rating is I am looking to possibly get a solar system and would like to use my existing panel.

Anonymous by private email Feb 7, 2022

Moderator reply: 3 safety hazards seen at GTE-Sylvania Electrical Panel - Rule of 6, Rust, Zinsco-Design

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The amps rating of the panel box is often on a label on the inside of the cover or on occasion on the sidewall inside of the electrical box - something your electrician can find if it's still there.

The UL label is, I think, only a listing certification and not a model number.

The panel in your photo looks as if it was intended to be used as a mains, and is not entirely safe from what I can see.

Concerns raised simply by inspection of your photos include

• Electrical panel rust that can impair safe circuit breaker operation - explained
  
  at
  
• A violation of the rule of 6 that has 7 breakers in the panel - explained as the "Rule of Six Circuit Breakers"
  
  at MAIN ELECTRICAL DISCONNECT
• This is probably a Zinsco-circuit breaker & bus electrical panel design - GTE-Sylvania Zinsco that is unsafe
  
  Watch out: Given the burn-up and trip hazards of these breakers I can't advise connecting a generator to it as really the panel should be replaced.
  
  In general you would never connect an electrical generator, such as a backup generator, directly to an electrical panel period. Doing so risks killing an electrical worker outside the building as well as overloading the generator and other lesser concerns.
  
  Details are also at GTE-SYLVANIA-ZINSCO FAILURE MECHANISM

Please see ELECTRIC PANEL AMPACITY for more detailed help in answering your question.

I'd be grateful if you'd post your photo and question there.

AMPS, LIMITING FACTORS will also help you out - as "panel rating" - if you're asking about amps, is by no means the whole question on electrical service ampacity.

Watch out: from the panel label and external appearance of the circuit breaker toggle switches, it looks as if as your panel is one of those that are unsafe and should be replaced.

See details of the hazard at ZINSCO SYLVANIA ELECTRICAL PANELS as well as above on this page.

- Feb 7, 2022

On 2020-12-04 by (mod) - do not hook up a generator to this GTE Zinsco Sylvania panel - replace it

Typically that panel is arranged as a "split bus" design - which adds additional safety concerns to its continued use.

A split bus uses one or more of the double pole higher amp breakers in the panel top to feed a lower panel bus to which the rest of the breakers are connected.

[Click to enlarge any image]

In your panel there are two red stickers with arrows: one pointing "up" indicates that the upper portion of the panel contains multiple (Two in this case) main disconnect breakers and the lower portion of this split bus panel contains individual circuit breakers.

The upper and lower "Do not Remove this K.O." white stickers telling you not to remove those "knockout" pair of opening covers. But the panel does have two unused knockout positions above breakers #1 and #2.



Instead the generator is connected to the panel THROUGH a transfer switch - an "either-or" type switch that makes certain that both power systems are not ever turned on simultaneously.

A good place to start reading about proper generator hookup is

at BACKUP ELECTRICAL GENERATORS

where we discuss, among other topics,

HOW TO WIRE UP an ELECTRIC GENERATOR and ISOLATION SWITCH REQUIREMENTS

On 2020-12-04 by BW Simmons - I want to add a 30 amp breaker to the panel to add a portable generator

My Missouri home was built in 1978. It looks like I have the unsafe Sylvania GTE panel.

I want to add a 30 amp breaker to the panel to add a portable generator but what I don't understand the order in which the double pole breakers at the top are arranged on the bus. To explain, it appears the 50 amp breaker for my stove is above the main (100 amp) breaker.

Makes no sense to me how I could add a 30 amp breaker with this set up. Not sure what amp panel I have either - looks like maybe 150 amp.

What are your thoughts about this panel set-up? What advice can you give me for connecting a generator. Panel info: 20-5X(10-20) C Mod. 1. 225 amps max

Question: Is this a Zinsco Sylvania electrical panel?

...

[Click to enlarge any image]

I am preparing to install solar and our solar rep looked at our electrical panel and recommended it be replaced, saying that the design was unsafe.

I was skeptical, figuring he was trying to upsell me. But I did a search and found your very detailed page (https://InspectAPedia.com/electric/GTE_Sylvania_Zinsco_Identification.php) on the topic.

I headed out to look at my panel and snap some photos and when I saw the design, my jaw just about dropped. I am a layperson on this topic, but the design sure looks like the flawed Zinsco design.

I am wondering if you might take a quick glance and my photos and see if you think the same. I have put them into a gallery here…[link deleted]

I would GREATLY VALUE your opinion. Thanks!

Reply: Yes, and there are additional interesting things to see in this GTE-Sylvania Zinsco main electrical panel

Yes your electrical panel is indeed the Zinsco-Sylvania design, that we can see in both labeling and in the unique Zinsco breaker and bus design that shows deep slots into the breaker that slide over vertical edges of the bus bars in the electrical panel.

Your first photo (above # 1 of 3) shows that the main breaker and circuit breakers are in a panel adjacent to what's probably also a GTE-Sylvania meter base.

Your second photo above shows cardboard inside of the electrical panel, perhaps stuck there to hold a neutral or ground cable to one side in the enclosure. But in my OPINION this is an unsafe situation: it's not a great idea to include fire-kindling inside of an electrical panel!

Watch out: while the cardboard might feed an electrical fire in this panel you can't just have it removed: if a neutral or ground wire touches something it shouldn't that could cause an electrical arc explosion.

An electrician needs to look with care at this panel for any immediate safety hazards, pending its replacement.

In the third photo above I mark with red arrows the distinctive deep notches into the side of a Zinsco-design circuit breaker and the vertical or on-edge aluminum bus bars to which the breaker clips. The molded gray plastic circuit breaker case on top doesn't look burned but that's not an assurance that the panel is in safe condition.

For example we often find burned breaker-to-bus connections that are not visible until the breakers have been removed. (Don't try it.)

In that photo I also circle characteristic light green GTE-Sylvania-Zinsco circuit breaker toggle switches.

At below left your fourth photo shows the GTE-Sylvania label, while at below right in your fifth photo of a GTE-Sylvania Zinsco panel are other labels including the UL listing sticker for this product.

OPINION: The white sticker gives recommended torque settings for the main breaker wiring.

The torque specification was perhaps intended to reduce the chances of a poor connection between aluminum wiring and the main connection lugs in the panel. Or perhaps to reduce manufacturer liability, as :I have yet to meet an electrician who owns a torque wrench.

...

If this were my electrical panel I'd replace it. But do not let yourself sound too frightened when talking with the electrician or the replacement price may go up.

 

Reader Question: are these Zinsco Electrical Panels & Breakers? I was told I had to remove them.

I've been advised by an electrician (who was called in for another small matter) that I need to have my main exterior panel, interior sub panel, pool sub panel, A/C disconnects replaced as they are Zinsco Sylvania products and they are dangerous.

...

I have searched the web and cannot find any of the identifying marks of a Zinsco panel on the panel I have.

It does day Sylvania and has what I assume is the model number: 390-205-09 on a label which has the bottom left corner torn off. Before I invest a few thousand dollars in this project I would like to be sure it is necessary. Can you assist with that?

I went to those sites and still cannot determine if mine is a Zinsco. I am sending you a picture, can you tell if it needs to be replaced? Thank you so much for your help.

Reply:

Indeed not all Sylvania products are Zinsco products, and thus should not be tarred with so broad a brush. Zinsco circuit breakers and the buss connections they use are easily identified regardless of the loss or absence of panel labels. But in your case we can see the familiar label in your photographs.

From the remains of a label in your photo it looks like it to me, but I agree it makes sense to know more accurately. To know with confidence what the breakers are in the panel an electrician will remove the cover, pull a breaker and compare it with the breaker designs illustrated as characteristic of Zinsco.

Or if your electrician doesn't know how to look at the Zinsco breakers we've illustrated, have her take some sharp photos of all sides of the breaker and email them to me.

Reader follow-up:

My electrician told me they were Zinsco and had to be replaced. I wanted corroboration so I could be sure I wasn't buying something that I really didn't need. - P.G.

Reply:

"Had to" is a technical opinion with which I agree. It is not a law. Your electrician agrees that the circuit breakers are a latent hazard - risking failing to protect your home from a fire or injury should an over-current hazard occur, so he or she recommended replacement.

I agree with that advice, but I acknowledge that the data base of tested Zinsco equipment confirming the failures is smaller than that of the FPE Stab-Lok hazard discussed elsewhere at InspectApedia.

Reader Question: is this Sylvania™ MLB20 (15-30)C Indoor Electrical Panel a Zinsco Product?

I have an MLB20 (15-30)C indoor mod 2 breaker box, is this prone to problems?
I [will] send pictures ...

... ...

Sylvania Electrical Panel Catalog No. MLB20(15-30)C Indoor 225A MAX. This panel, in photos above, uses a Zinsco type bus design.

Reply:

I'd indeed like to see photos of the breaker panel you cite, in total, its labels, its bus bar design and its breaker details and labels.

But Watch out: opening an electrical panel, if you touch what you shouldn't means dead Larry (or Dead Daniel if I do it).

If the panel you describe is of the classic Zinsco design described in these pages there is risk of breaker-bus arcing and the other hazards described for Zinsco. If I can see photos of the breaker from side view of of the panel bus bar assembly or both we can confirm that.

Follow-up:

Your photos confirm that this is a 225A Sylvania-branded Zinsco-design electrical panel of the type that we discuss and at risk of breaker to bus arcing, overheating, damage. It would be prudent to replace it.

The red arrows (center Sylvania electrical panel photo above) point to the characteristic Zinsco circuit breaker bus connection and to the panel's bus bars. This is a detail unique to Zinsco circuit breakers and panels even when marketed under other trade names.

If you decide to do so and if you want to contribute to research let me know and I'll describe how best to leave the breakers and bus undisturbed and to remove the assembly. I can ask Dr Aronstein if he can test this Sylvania - Zinsco electrical panel before we disturb conditions by actually pulling breakers.

On 2020-08-26 by Jason SPS

Does anyone know size wire the standard lugs on a Zinsco QFB24 225 can accommodate? It is a 3 Pole 225A breaker and we would like to run 250MCM

On 2020-07-11 - by (mod) -

No, Mary all of your photos were quite tiny, but nevertheless we reach the same conclusion:

Those red and light blue (?) circuit breakers are characteristic of Zinsco-design breakers.

Bottom lien:

It is a Zinsco type electrical panel and should be replaced.

On 2020-07-10 - by (mod) - is there is a way to tell if this is a Zinsco brand

Mary c

Your panel photo so tiny I can't see much, but those red and light blue (?) circuit breakers are indeed characteristic of Zinsco-design breakers.

Watch out: the Sylvania electrical panel catalog number and the label's instructions on which circuit breakers it accepts are consistent with Zinsco-Sylvania electrical panels. That's probably what you've got.

I'd like to have seen a view of the actual circuit breaker from its side or a view of the metal bus bar to which the breakers connect as that will give an absolute identification. Try posting a larger photo of that detail.

Watch out: you've got the electrical panel cover off completely. Do not touch anything inside the panel. Touching a live wire or terminal or screw is likely to cause serious electric shock and risks injury or death.

Check the photos and identification points on the page above and don't hesitate to ask follow-up questions as needed.

On 2020-07-10 by Mary C

I am wondering if there is a way to tell if this is a Zinsco brand. I have a buyer that wants me to put in a new panel because it might be.

• Sylvania electrical panel Catalog No. MLB20(12-24)C (Indoor) Mod. 2, 225AMPS Max.
• Use GTE Sylvania Circuit Breakers type Q, QC, AFP, R38, RC38, and HRGF.

I will do another post with another picture. Thank you

On 2020-07-04 by (mod) - Vertical or "on edge" electrical panel bus bars identify a Zinsco design

Sean

Unfortunately, yes, that's a Zinsco-Sylvania panel design. Notice those two vertical strips that connect to two deep slots in the circuit breaker?

That identifies this as a Zinsco design. Here I'll post a closer-view excerpted from your photo.

On 2020-07-04 by SeanN

Here's a pic of inside panel

Hello,
Thank you for all the information - I don't think this is a Zinsco panel, but would you be able to confirm?
Model# is MT12MBB and House was built in 1977 in San Mateo County, California, USA.

I'm looking to upgrade to 200A with solar system in future but trying to decide if I should replace it now if it's unsafe.
Please see attached - Thanks!
Sean

...

Continue reading  at IDENTIFY ZINSCO SYLVANIA METER BASE or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see IDENTIFY GTE SYLVANIA-ZINSCO PANEL FAQs - questions and answers posted originally on this page.

Or see this

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