Zinsco circuit breaker & electrical panel identification guide:

How to Identify Zinsco & Zinsco-Sylvania & GTE-Sylvania-Zinsco Electrical Panels and Circuit Breakers. Identify Zinsco-like Sylvania Electrical Panels and Circuit Breakers. Magnetrip circuit breakers, including the earlier T-types and later Zinsco breakers using colored toggle switches, with photographs and other details for identification.

We include photos of Zinsco breaker labels and other markings that identify Zinsco and Kearney electrical equipment.

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.

5 Ways to Identify Zinsco, Zinsco-Sylvania, GTE-Sylvania-Zinsco, Kearney Electrical Panels & Breakers

To identify a Zinsco or Zinsco Sylvania or Kearney electrical panel look for the following:

1. The word Zinsco on the panel door tag,

on panel labels or data tags (Zinsco panel label photo above). [Click to enlarge any image]

2. The word Magnetrip embossed

in the steel electrical panel cover or on data tags in the Zinsco electrical panel. (Zinsco electrical panel photo below)

3. The characteristic colored Zinsco red, green, blue, gray & white toggle switches

on the circuit breakers in the Zinsco electrical panel. (Photos below)

Shown above in a very crowded collection of circuit breakers, we see two-pole Zinsco RC half-sized breakers in three different amperages. It looks as if some, but not all of these Zinsco RC38 breakers have their toggles tied together.

These Zinsco circuit breaker toggle or "handle" colors identify the ampacity of the individual circuit breakers as follows

• 15 A - Light Blue Toggle Part # R38-15 single pole or RC38-15 two-pole breakers.
• 20 A - Red Toggle Part # R38-20 or RC38-20 double pole
• 30 A - Light Green Toggle Part # R38-30 single pole or RC38-30 two-pole half-width breakers in a closer view in the photo just below.
  
• 40 A - Light Gray Toggle Handle Part # RC38-40

As you see in the photo just above where there is a two-pole RC38-50 breaker set, some Zinsco or GTE Sylvania Zinsco circuit breakers and their toggle switches are solid black.

Watch out: you will also find some 30A - Black toggle Zinsco breakers and 20A black-toggled GFCI breakers that, as you'll see illustrated below on this page.

So don't assume that all-black breakers can be excluded from this unsafe Zinsco circuit breaker group.

• 50A - Black Toggles, Part # RC38-50 - shown above
• 60A - White Toggle or handle, Part # RC38-60 (not shown in the photo above)
• 100A double pole - Black - shown above

Above is an example, a Zinsco R38 Tandem circuit breaker sporting light blue toggle switches. I saw this listed as 50A but am doubtful. It's probably a 15A Zinsco tandem circuit breaker.

• Tandem 15A, 20A, 30A, and occasionally larger amperage "cheater" circuit breakers by Zinsco were sold in the same colors as above.
  
  These Zinsco breakers squeeze two toggles and two circuit breakers into a single traditional circuit breaker width.
  
  Zinsco tandem circuit breakers included two breakers of the same amperage (above) but were also manufactured and sold providing two circuit breakers of different ampacity within the same case, like the Zinsco-Sylvania RC381520 circuit breaker shown below.
  
  These Zinsco tandem circuit breakers can also be readily identified out of the panel by the characteristic deep bus bar slot in the breaker side.
  

• Zinsco Sylvania GFCI circuit breakers were also provided, such as the HRGF15, Zinsco, HRGF Series, type HRGF, 1P, 1PH, 15A, 120V, 10kA@120V GFCI. (Obsolete, not recommended)
  
  Shown below, Zinsco HRGF30 circuit breaker recently (6/22) observed for sale by an online vendor, described as "refurbished". This 30A Zinsco shows a red toggle switch color.
  

Some Zinsco / Zinsco-Sylvania GFCIs follow the color conventions we show above, But others do not. Below is a Zinsco HQGF20 GFCI circuit breaker with a black toggle switch.

4. The unique vertical thin-edged bus bars

(aluminum, plated aluminum, or in older Zinsco panels copper bus bars (inside the panel accessed by a licensed electrician).

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. Photo courtesy Tim Hemm cited at references at the end of these articles.

5. The unique deep slotted circuit breaker connector openings

that press over the bus bars (inside the panel accessed by a licensed electrician)

Below is an enlargement of the the bus-connection section of a classic Zinsco circuit breaker - showing the difference between these devices.

Just below, the photo of a recent GTE Sylvania Zinsco circuit breaker burn-up is shown here courtesy of Jeff Weissman and observed, he reports, in a GTE-Sylvania electrical panel.

This gray circuit breaker may have been installed in a GTE-Sylvania electrical panel but is breaker did not use the Zinsco-design circuit breakers and/or may be of a different brand or manufacture.

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

Some Zinsco electrical panels include an embossed "Magnetrip" label in the panel cover (photo, above left). Other Zinsco electrical panel identification and information labels are included in this article.

[Click to enlarge any image]

• Zinsco Main Panel, note the embossed "Magnetrip" label at the top of the panel face
  
• "Magnetrip" closer view of this embossed label
  
• Zinsco blue/silver label in the panel, and the characteristic green, white, red circuit breaker toggles
  
• Underwriter's Laboratory Label, closeup of this yellow on black UL label in a Zinsco electric panel
• A Zinsco Electrical Panel, cover off: note the red and blue breaker toggles and the breaker removed to show evidence of arcing in this Zinsco electrical panel.
  
• Zinsco circuit breaker labels-1
  
• Zinsco circuit breaker labels-2
  
• Zinsco Main Panel Label, closeup of the red print on black "Zinsco Los Angeles label"

IDENTIFY Zinsco HD - 4032 400 Amp, 2 pole, 240V AC Electrical Panel

Above and below, courtesy of Richard Sims, we include photographs of a 400A 240V Zinsco Electrical Panel that was property of the Georgia (USA) Power Company, including identifying Zinsco labeling.

The Zinsco panel exterior is shown above and in close-up below.

The photo above shows the distinctive operating handle on the door of this Zinsco electrical panel.

Here (above and below) we show external and internal identification labels for this 400-Amp Zinsco electrical panel. The electrical panel is also tagged with the electrician's card, Jim Wise, owner, Wise Electric.

Below we show the interior of this 400Amp Zinsco electrical panel.

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

Zinsco 400A 120/240VAC DS-4564 DS-4564 Panel ID Photos

Question:

I'm looking for information on a Zinsco single-phase 400A, 240VAC panelboard with a DS-4564 designation. I'm looking for the AIC rating of the big double throw AC cutoff switch on the front. Can anyone help me? - Anonymous by private email 2019/01/30

...

Reply:

I cannot see anything of the main breaker in your Zinsco panel so it's ampacity could differ, but the panel label describes a 400Amp panel single phase, 120/240VAC unit.

Actually that top component labeled "Main" looks like it could even be a fuse pull-out. [Click to enlarge any image]

Watch out: the panel looks corroded, rusty, unreliable as a brand-independent hazard, and of course Zinsco breakers and panels are unsafe in any event.

Please see details at ZINSCO SYLVANIA ELECTRICAL PANELS

Other Sylvania or Sylvania-Zinsco Electrical Panels & Circuit Breakers

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

Frank Adam Electrical Panels - Frank Electrical Panels

Frank Adams Electrical panels were installed in buildings in the U.S. roughly between 1900 and 1970. Research is underway. Contact us if you have photos of a Frank Adams electrical panel or other details.

Identification photos of Frank Adam electrical panels are

at FRANK ADAM ELECTRICAL PANELS

and at HISTORY of ZINSCO ELECTRICAL PANELS

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Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

On 2023-08-04 by InspectApedia Publisher - Zinsco electrical panel shows burned, overheated electrical connections, risking fatal shock hazard

@Shana Duran,

This photo is definitely a Zinsco or Sylvania-Zinsco electrical panel - it has the characteristic on-edge bus bar that mounts into a deep slot in the circuit breaker. Compare what you're seeing in the panel with Zinsco photos above on this page.

Watch out: those exposed panel bus and wires are a fatal shock hazard.

Watch out: both of your photos show burned, overheated electrical connections - this electrical panel and breakers are unreliable and unsafe and should be replaced.

On 2023-08-04 by Shana Duran

Trying to verify the is not a zinsco but instead a unicorn..please and thank you

This is the breaker attached to the panel door

On 2022-10-28 by InspectApedia-911 (mod) - Arizona manufactured home shows Zinsco type circuit breakers

@Charles,

The last photo in your series shows Zinsco type circuit breakers.

If there were ANY circuit breaker that would be my top priority to replace it'd be the one providing the high-amp service entry like that 100A double pole Zinsco in your photo.

On 2022-10-20 by Charles

@InspectApedia (Editor),
That’s my understanding reading through the various forums and boards that have discussed the issue. However, in my case because I live in a manufactured home park, I don’t own the land or technically the utilities.

Also, since it’s a double sided unit, I’d have to get my neighbor on board to go 50/50 on replacing it as well as permission from management. My home was built and set here in 2019. It was a lease-only unit until my wife and I bought it earlier this year (2022).

For its age, it is in great shape. I guess one of the benefits of living in the desert in Arizona. I’ve done what I can to help the current draw by installing a soft-start on my AC unit. Not only will that help add years to the unit, but will also curb electricity usage.

On 2022-10-20 by InspectApedia (Editor)

@Charles,

Thank you for the photos and discussion. I hope you will read the articles in this series so that it will be as clear as possible that those Zinsco circuit breakers are fire hazard and that the safe solution is to replace the panel with one from a different manufacturer.

On 2022-10-20 by Charles

Pretty sure the electrical pedestal for my home is a Unicorn. This is a dual sided unit, both metered, and the rear side still has the original Unicorn breaker plus a 30 amp and 50 amp RV connections.

The primary reason I was looking into this was to add a breaker to a sub panel for my tiny workshop. The breaker part is easy, it’s the neutral connection I am struggling with. I believe I have figured it out and plan to move forward on making the connections since I’ve roughed in my electrical.

It’s so hard to find good information and why I’m posting my pictures, so others who have questions will hopefully get answers.

A view of the entire pedestal.

Here’s the back side.

On 2022-06-20 by InspectApedia (mod) - 5 ways to identify Zinsco breakers

@Joe Levis,

Your question is a good one and we answer it on this very page.

In addition to the many identification photos, we describe 5 ways to identify Zinsco, Zinsco-Sylvania, GTE-Sylvania-Zinsco, Kearney Electrical Panels & Breakers.

There is also a list of relevant recommended article for added information.

Please do take a look.

On 2022-06-20 by Joe Levis

How can you identify Zinsco Circuit Breakers with Pictures?

(reposted by moderator without disallowed link)

On 2021-08-30 by inspectapedia.com.moderator (mod) - History & Hazards of Zinsco-Design Unicorn Electrical Panels & Breakers

@Unicorn electrical products?,

The Pick M'Amp circuit breaker, designed based on Zinsco's problem circuit breaker and bus design, was produced by Unicorn Industries.

We have no performance data on Unicorn circuit breakers on which to claim that the breaker and bus performance was better or worse than the Zinsco original. Understanding the Zinsco failure mechanism is pertinent and is discussed in this article series.

It appears that the present Unicorn Industries has nothing to do with the old meter base in your photo; the current Unicorn describes themselves:

as providing "information systems for the European energy industry and utilities. " https://unicornsystems.eu/

Some history of Unicorn Industries circuit breakers is at

Kosup, Russell R. MULTIPLE CAPACITY CIRCUIT BREAKER [PDF] U.S. Patent 4,187,482, issued February 5, 1980. Application filed by Unicorn Industries Inc..
Excerpts:
This invention relates to circuit breakers, and more particularly, to a breaker in which the rated current level is preset by a removable cam element.
...
The present invention is directed to a relatively inexpensive circuit breaker of the type commonly used as the main breaker in a household electrical service unit in which the rated capacity can be preset by a plug-in cam element made of inexpensive molded plastic material. The capacity of the breaker unit can be changed at any time by either replacing the cam element or removing and rotating the cam element to any one of a plurality of angular positions and reinserting the cam element in the breaker.

An interlock arrangement insures that the cam element can not be removed without the breaker being automatically tripped. This is accomplished, in brief, by providing a breaker having a switch unit by which shunt current paths of different resistance can be selectively connected in parallel across the current path in which the current is sensed for activating the trip mechanism at a predetermined current level. The switch unit is set by a plug-in cam, the angular position of the cam when it is inserted in the breaker operating the switch unit to selectively complete one or more of the shunt current paths.

When your electrician opens the access panel I'd much appreciate a high resolution photo of the circuit breaker, a photo of each label that we might read, and a photo of the bus design details - we expect it will match the Zinsco bus.

Back in 2013 over at electriciantalk.com an electrician who was familiar with Unicorn Electrical products commented:

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Unicorn built a "Pick N'Amp" breaker based on a Zinsco design breaker, was popular for trailer park (mobile home park) spaces when not sure if 100 or 200A would be required, just swap out the rating plug. The idea is good but why use a garbage design? Since Milbank still uses a Zinsco design breaker, prefer to keep them on my "do not buy" list.

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Bottom line:

Your electrician simply needs to look at the connector bus and breaker to determine if it's a Zinsco design.

It's easy and unmistakable.

Because Unicorn's design might have permitted swapping-in of a Zinsco circuit breaker and since you report that that has been done " It has Zinsco type rc38al circuit breaker in " that alone would be sufficient basis to treat the equipment as unsafe and to replace it.

On 2021-08-30 by Unicorn electrical products?

Hi all what about unicorn electrical products? It has Zinsco type rc38al circuit breaker in it.

[Photo above]

On 2021-08-25 by inspectapedia.com.moderator (mod)

@Robert shaner,

Maybe try again; type in the Comment box, then click the "Add Image" button to select an image file from your computer or smartphone or tablet.

On 2021-08-25 3 by Mod

@Robert shaner,

Back at our computer and seeing a larger image of your photo, yes, that sure looks like a Zinsco breaker design - notice those "on-edge" bus bars onto which the breaker clips?

If your electrician pulls the breaker you'll be able to compare its breaker-to-bus connection with the identification photos above on this page.

On 2021-08-21 by inspectapedia.com.moderator (mod)

@Robert shaner,

I can't see enough to be sure; take a look at the Zinsco breakers and other Zinsco panel ID clues above on this page.

For example, the deep slot that cuts up into the side of Zinsco breakers and the "on-edge" bus bars are key details that will reliably identify Zinsco breakers and panels and can be easily seen in an electrical panel.

Watch out: your photo shows live voltage terminals exposed: don't touch or you can be shocked or killed.

On 2021-08-21 by Robert shaner

Is this 100 amp breaker from 1965 a zinsco breaker?

[Photo above]

On 2018-08-18 by (mod) - how to find the age of a Zinsco 200A panel

Thanks for an excellent question, Randy.

Estimating Electrical Panel Age

I'm sorry to say that I have not found a credible Zinsco electrical panel age decoder. Often the panel manufacture date is stamped on the panel labeling but not always and not in a consistent patterns. Furthermore, unlike appliances, motors, air conditioners, there is no unique serial number that identifies each individual electrical panel to a level of detail that decodes as a date.

If I were estimating an electrical panel age I would

1. Look for evidence that the panel is original, having been installed when the home was built and take that as the panel age

2. Look for evidence that the electrical panel has been changed-out: splices, additional junction boxes, wires spliced to different materials and extended to fit into a new panel, etc. - and then look for remodeling and renovation dates on the panel and in the home's documentation.

3. Look for an electrical inspector's stamp of approval of the installation - those, if present, are dated and signed.

4. Note the panel style and construction details and then see

HISTORY of ZINSCO ELECTRICAL PANELS at https://inspectapedia.com/electric/Zinsco_Electrical_Panels.php#ZinscoHistory

On 2018-08-18 by Randy lacy

How do I find the year my electrical panel was manufactured. It's a zinsco enclosed 200 amp issue no. 3057

On 2017-10-08 by Joe JRL Electric Supply

Re-posting without Joe's advertisement

Joe JRL Electric Supply said:

The replacements for zinsco do not make the 35 amp any more. It would have top be purchased used only.

Moderator comment:

Watch out: replacement circuit breakers that have been tested for these problem brands have generally performed no better than the originals. Joe's advice is in our opinion bad and unsafe.

On 2017-09-09 by John

Is a green Zinsco breaker 30 amp?

On 2016-11-12 6 by (mod)

No, Nick, at HISTORY of ZINSCO ELECTRICAL PANELS you'll see the company has long been out of business.

Third party vendors may produce "zinsco replacement" breakers but testing has shown they perform no more safely than the original ones. Replacement is not, in this case, recommended.

On 2016-11-12 6 by nick

zinsco still make 35 amp breakers? single pole, yellow handle

...

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

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