Identification guide
Zinsco and Sylvania-Zinsco panels: how to identify one, and what the evidence actually supports
Zinsco is written about with the same confidence as Federal Pacific Stab-Lok. The evidence behind the two is not the same, and a homeowner deciding whether to spend a few thousand dollars deserves to see the difference.
Written by HyreElectrical Research Desk Primary-source research and fact checking
The direct answer
You identify a Zinsco panel from the label and the breaker type code, not from the color of the handles.
If the nameplate or breaker faces read Zinsco, Magnetrip, Sylvania-Zinsco, GTE-Sylvania or Challenger, or the breakers carry type codes Q, QC, QCB, RC, T or catalog numbers beginning R38, you are looking at the Zinsco design.
Then the harder half. There is no CPSC recall of Zinsco panels or breakers — we queried the federal recall database on three fields and publish the search below.
There is no closed CPSC investigation of Zinsco, as there is for Federal Pacific, and no consumer-fraud judgment.
The hazard case rests on field-inspection consensus and on insurer underwriting rules — both real, both costly, but not the same standard of evidence.
Anyone who tells you Zinsco panels were recalled has told you something that did not happen.
Identification comes first, because most panels blamed on Zinsco are not Zinsco
Zinsco, Federal Pacific Stab-Lok, Pushmatic, Wadsworth and Challenger get confused for one another, and the advice for one is wrong for the next. Everything below is read from the outside of the panel.
Look for Zinsco, Magnetrip/Magnatrip, Sylvania-Zinsco, GTE-Sylvania or Challenger. The same design was sold under all of these as the business changed hands, so door and breakers may not match. Photograph both.
Types Q and QC (the “thick” series), RC and catalog numbers beginning R38 (the “thin” series), T, and QCB for the bolt-on commercial version. Source fact: those designations are how Connecticut Electric, the one firm currently manufacturing new replacements, indexes its Zinsco line.
Almost every consumer page identifies Zinsco by red, blue, green and black handles. We could not trace that to any primary document — no patent, no catalog we could open, no standard. If label and type code disagree with the color, believe the label.
A Stab-Lok panel says Federal Pacific Electric, FPE or Stab-Lok, and carries a CPSC investigation that closed in 1983 without a safety determination — a federal record Zinsco does not have. See replacing a Federal Pacific panel.
Sylvania was a large electrical brand. A Sylvania label is a reason to check the type codes, not a diagnosis.
A phone photograph of the nameplate and breaker faces is enough for a licensed electrician to identify the panel without anyone opening anything.
Where you stop
Everything on this page is done with the dead front on. Behind that inner metal cover the main lugs are energized at line voltage even with the main breaker switched off, and that is true of every panel, not only these.
Do not remove it, do not pull a breaker, do not tighten anything, and do not test a breaker by loading the circuit until it trips. If the identification stops at the door, that is the correct place for it to stop. The next step is a licensed electrician.
Find a local electrician to look at the panel
Free, with no obligation. A person at HyreElectrical reads it and replies. Matching with electricians is not live yet.
Every name this one product was sold under
Taken from patent assignee records only, because that is what we could actually open. Commonly repeated dates we could not trace are marked as such.
- Zinsco Electrical Products
- The Los Angeles manufacturer. Patents assigned to it run from at least 1950 (US2502537A) to the mid-1970s, including the bussing patents quoted below.
- Magnetrip / Magnatrip
- The breaker trade name on many Zinsco faces. We could not verify it in a trademark or corporate record — the USPTO trademark search API was not publicly reachable on 6 September 2026. A label to look for, not a sourced fact.
- GTE-Sylvania / GTE Products Corporation
- Source fact: patents in the same panelboard family are assigned to GTE Products Corporation, granted 1982 and 1983 (US4366528A, US4369484A). HYRE analysis: that establishes GTE ownership by the early 1980s. The repeated “acquired by GTE-Sylvania in 1973” date is not asserted here; we found no primary record of it.
- Challenger Zinsco, Inc.
- Source fact: US4500863A, granted 19 February 1985, is assigned to Challenger Zinsco, Inc. The design outlived two changes of owner, which is why the door brand is a poor guide to what is behind it.
- What the recall record says about Challenger
- CPSC did recall a Challenger product — 9,000 type HAGF ground-fault breakers made February to April 1988, because a mechanical part could detach and disable the ground-fault function. That is not a recall of Zinsco panels.
The asserted failure mode, in the manufacturer’s own words
Inspectors claim the breaker-to-bus connection degrades, the joint heats, and in the worst description a breaker appears off while the circuit stays energized. We went to Zinsco’s own patents for what the connection physically is. The patents establish the construction. They do not establish a failure rate.
The connection is a clip that slides onto a blade
Source fact. Zinsco patent US3389307A, “Mating circuit breakers with spaced bus clips”, filed 30 January 1967 and granted 18 June 1968, describes a U-shaped clip formed as “a unitary piece of conducting metal with the external bus clip formed integral therewith”, which “slidingly grips a bus blade”.
HYRE analysis. A sliding spring clip is a pressure connection, only as good as the pressure it retains — the physical basis of what inspectors describe, but not by itself a defect; the same approach is used industry-wide.
The bus plates are aluminum, by specification
Source fact. Zinsco patent US3995103A, “Electrical bussing and jumper assembly”, filed 11 December 1975 and granted 30 November 1976: “A suitable material for the bus plates 2, 4 and 6 is aluminum (1/8 in. thick)”, with the flat pad sections “preferably plated with tin”.
HYRE analysis. The most-repeated Zinsco claim is the one part documented by the manufacturer. What the patent does not say is that the alloy was defective or that joints failed at any rate; plated aluminum busbars remain in ordinary commercial use.
The claim that is asserted rather than documented
The strong version — a breaker welded to the bus still passing current with its handle off — is reported consistently by inspectors and electricians.
We could not locate a controlled test, a federal investigation or a published failure-rate study specific to Zinsco that we could open and read.
That absence is not proof the reports are wrong; it is why this page prints no number.
Every CPSC circuit-breaker recall since 1988 — and the search that found no Zinsco
HyreElectrical queried the CPSC recall database directly through the public SaferProducts REST service on 6 September 2026. ProductName=Zinsco, RecallTitle=Zinsco and Manufacturer=Zinsco each returned empty.
An empty result is only meaningful if the query works: ProductName=Circuit Breakers returned the 12 records below and ProductName=Load Centers returned the 2022 Schneider recall of about 1.4 million Square D QO load centers.
| Recall | Date | Units | The hazard, as CPSC stated it |
|---|---|---|---|
| Schneider PowerPact J-Frame | 18 Dec 2014 | 62,500 | “The circuit breaker will not trip during an overload condition.” |
| Square D F and K Frame | 18 Mar 2014 | 28,400 | “The circuit breaker can fail to trip when an overload occurs.” |
| Siemens breakers — bus connection | 23 Sep 2010 | 2,200,000 | “A spring clip that can break during normal use, leading to a loss of force to maintain a proper electrical connection in the panelboard… excessive temperature, arcing or thermal damage at the connection point.” |
| Counterfeit Square D (Miami Breaker) | 2 Aug 2010 | 43,600 | Counterfeit; “can fail to trip when they are overloaded.” |
| Counterfeit Square D (Specialty Lamp Int’l) | 27 May 2008 | 371,000 | Counterfeit; “can fail to trip when they are overloaded.” |
| Counterfeit Square D (North American Breaker) | 27 Dec 2007 | 50,000 | Counterfeit; “can fail to trip when they are overloaded.” |
| Counterfeit Square D (Connecticut Electric) | 30 Oct 2007 | 64,000 | Counterfeit; “could fail to trip when they are required to.” |
| Counterfeit Square D (Scott Electric) | 16 Nov 2006 | 30,000 | Counterfeit; “might not trip when they are overloaded.” |
| Square D — lug torque | 9 Aug 2002 | 40,000 | “Incorrect torque load applied to the lug mounting screws… could overheat.” |
| Siemens GFCI for hot tubs and spas | 7 Oct 1998 | 144,000 | “Could overheat and lose their ability to prevent injury or death.” |
| Challenger HAGF GFCI | 12 Nov 1988 | 9,000 | Electrocution / electric shock. A mechanical part could detach and disable the ground-fault function. |
| Square D Series 1 GFCI | 13 Apr 1988 | not published | Electrocution / electric shock. No unit count published in the record. |
CPSC recall records, SaferProducts REST service, 6 September 2026. Chart and table are generated from the same array; the 11 recalls with a published unit count cover about 3,042,500 breakers.
Federal Pacific returns nothing from this database either — consistent with the 1983 CPSC news release, which closed the FPE investigation without a determination. Neither product was ever recalled by CPSC.
What it looks like when this exact failure mode is proven
Source fact. On 23 September 2010 CPSC and Siemens recalled about 2.2 million circuit breakers.
The stated hazard: a “spring clip that can break during normal use, leading to a loss of force to maintain a proper electrical connection in the panelboard”, which “can lead to excessive temperature, arcing or thermal damage at the connection point”.
HYRE analysis. That is, almost word for word, the mechanism asserted about Zinsco. The system is not reluctant about panelboards. On Zinsco it has no record at all — most likely not because Zinsco was cleared, but because nobody with subpoena power and a test budget ever looked.
The honest ledger: documented on the left, asserted on the right
Documented, with a source you can open
The construction. A sliding U-shaped bus clip (US3389307A, 1968) and aluminum bus plates with tin-plated pads (US3995103A, 1976), from Zinsco’s own patents.
The absence of a federal record. No CPSC recall on any of three query fields, against a database returning 12 other breaker recalls and the 2022 Schneider panel recall.
The insurance consequence. Orion180’s Texas Flex homeowners program, dated 13 January 2025, lists as ineligible “unsafe electrical panels, including but not limited to… Zinsco/GTE Silvania”. Quoted in full in our hazard-era research.
The disclosure law. California Civil Code §1102.6i, added by SB 382 (Stats. 2024, ch. 443), applies to sales on or after 1 January 2026.
Asserted, and you should know that it is
The failure rate. No controlled test specific to Zinsco was retrievable. The “29 percent of 111 breakers” figure on contractor pages could not be traced to any document we could open, so it is not printed here.
The off-but-energized breaker. Consistently reported by inspectors; not established by any test report we could read.
The handle colors. Universally repeated, primary source not found.
“Zinsco panels were recalled.” False. No CPSC recall exists. Where an underwriting guide groups Zinsco with panels “subject to a recall”, that is the insurer’s classification, not a federal finding.
“California now requires an electrical inspection.” Also false — the next section quotes the statute.
What California’s new disclosure law actually says
Source fact. California Civil Code §1102.6i, added by SB 382 (Stats. 2024, ch. 443), requires that on or after 1 January 2026 the seller of residential property subject to the disclosure article deliver a statement reading, in full:
“In a purchase of real property, it may be advisable to obtain an inspection by a qualified professional of the electrical system(s) of any buildings, including, but not limited to, the main service panel, the subpanel(s), and wiring.
“Substandard, recalled, or faulty wiring may cause a fire risk and may make it difficult to obtain property insurance. Limited electrical capacity may make it difficult to support future electrical additions to the building(s), such as solar generation, electric space heating, electric water heating, or electric vehicle charging equipment.”
Buildings sold within three years of their certificate of occupancy are exempt.
HYRE analysis. It does not require an inspection, and it names no brand. Pages telling California sellers the law compels an inspection are describing a statute that does not exist.
Can you still get breakers for it?
Source fact. Connecticut Electric of Anderson, Indiana publishes that it is “the only manufacturer of ‘NEW’, UL 489 safety agency tested, ETL listed replacement circuit breakers for these panels”, that its UBI line covers “Pushmatic, Federal Pacific, Challenger, Zinsco and Wadsworth”, and that the breakers “are always new, never refurbished or remanufactured”.
“The only safe choice” is marketing, quoted as such.
What “ETL listed to UL 489” means. ETL is Intertek’s certification mark; UL 489 is the product standard for moulded-case breakers. HYRE analysis: a real certification, and a different question from whether the breaker is listed for your panel.
NEC §110.3(B) requires listed equipment to be installed per its listing — and a 1968 panelboard label names the original manufacturer’s catalog numbers. Whether a third-party breaker satisfies that is your authority having jurisdiction’s judgment, and inspectors differ. Ask before you buy.
The used-breaker market is the part to be careful about. A breaker pulled from a fifty-year-old panel carries no current certification whatever marks are moulded into its case.
Counterfeits are a documented problem too: five of the twelve CPSC breaker recalls above are recalls of counterfeit Square D breakers, one of them — 64,000 units in October 2007 — issued to Connecticut Electric itself.
That recall concerned counterfeit Square D product, not the UBI line; we note it because a page quoting a company’s safety claim should also show its record.
Recommendation. If one breaker has failed and the panel is otherwise sound, a new certified replacement is a legitimate repair to discuss. If it is undersized, or you are adding an EV charger, heat pump or solar, you are having the panel upgrade conversation anyway.
Insurers, and the age of the house
The financial consequence usually arrives through insurance rather than through a fire.
Source fact: Orion180 Insurance Company’s Texas Flex Program Underwriting Guide, dated 13 January 2025, lists as ineligible “unsafe electrical panels, including but not limited to: Fuse boxes… Federal Pacific Electrical (FPE)… Zinsco/GTE Silvania… Challenger.”
That document, a second carrier’s guidelines, and the caveat that two published guides are not a market survey, are set out in The electrical panels insurers won’t cover.
The same research carries HyreElectrical’s analysis of the installation era: 67.1 million US housing units, 47.1 percent of the stock, were built between 1950 and 1989, computed from US Census Bureau ACS 2023 5-year table B25034.
That is a construction-era figure, not a panel count. Nothing in the ACS records a panel. Era tells you whether to look; it never tells you what you will find.
How to get a second opinion that is actually independent
The person diagnosing your panel is very often the person selling you its replacement. A structural conflict, not a personal one — but manage it as you would any large quote.
Photographs sent to two firms separately settle the brand question for free. If they disagree about what the panel even is, that matters.
A licensed electrician or independent inspector paid a flat fee to look and report, with no bid attached, has no stake in the answer.
Useful answers are observable: heat discoloration at a breaker position, a breaker that will not reseat, evidence of arcing, double-tapped conductors, no equipment ground. “Zinsco panels are dangerous” is a category statement, not a finding.
Is this panel eligible, and what would restore eligibility. A written answer converts a vague worry into a priced decision.
Our license lookup points at the state board’s own register. Panel replacement is permitted work almost everywhere, and a quote proposing to skip the inspection is telling you something about the firm.
HyreElectrical does not perform, supervise or warrant electrical work, and has no financial interest in whether your panel is replaced.
What this page could not verify
The closest peer-reviewed source — Aronstein and Carrier, IEEE Access vol. 6, pp. 10062–10068, 2018 — is real and open access, and its abstract states that the worst-performing brands failed the 135 percent trip requirement “in the order of 50%” for both used and newly purchased breakers.
The abstract names no brands, and IEEE Xplore refused the full text to this desk on 6 September 2026.
Our search establishes that CPSC has no Zinsco record. It does not establish that the panels are safe — “never assessed” is a different sentence from “assessed and cleared”.
Near-universal in the field literature; neither traceable to a primary document by this desk.
They prove the rule exists, not how many carriers apply it.
Assignee data gives ownership by the early 1980s, not an acquisition date, and we did not print one.
Questions
Were Zinsco panels ever recalled?
Is a Zinsco panel as dangerous as a Federal Pacific Stab-Lok panel?
How do I tell a Zinsco panel from a look-alike without opening it?
Does California’s SB 382 require me to have my panel inspected?
Written and audited by
HyreElectrical Research Desk
Primary-source research and fact checking
We read the model code, the federal safety notice, the municipal fee sheet or the utility tariff ourselves, and we publish the figure with the document it came from and the date we retrieved it.
Where a number cannot be traced to a primary source, we publish the shorter page and say what we could not verify. HyreElectrical does not perform, supervise or warrant electrical work. Authorship is organizational: this desk, not a named persona.
- 16
- original research studies published
- 5
- states with verified license records
- 16,369
- electrical companies in those records
- 74%
- of the store is Florida — disclosed first, not footnoted
How this desk works
- Primary sources only. Code statements come from NFPA 70 as the model code. Safety statements come from CPSC. Permit fees come from the city or county fee sheet. Utility charges come from the filed tariff. We do not cite a blog that cites a source; we open the source.
- Our contractor store is five states, and 74% of it is Florida. Any figure built on that store is titled to those states and names the concentration in the first screen. It is not a national sample of electricians.
- Load calculations on this site are a published simplification in the shape of NEC 220.82 — first 10 kVA at 100%, remainder at 40%, HVAC at 100%, EVSE at 125%. They are labeled as not a stamped calculation. A licensed electrician using the adopted edition does that work.
- No national price for a panel upgrade is shipped. Labor rates, the adopted code edition, whether the utility is involved, and the state of the existing wiring move the invoice too far for a roundup to help. The cost pages publish named permit fees and the variables that move the price instead.
- We do not perform electrical work, and we take no payment for placement, ranking or a favorable mention. Nobody buys a position on this site.
Data as of 6 September 2026. Authorship on this site is organizational: the analysis belongs to the desk rather than to a named individual, and we do not publish credentials we do not hold. Our editorial policy sets out how we source, date and correct what we publish.
Sources & retrieval dates
Think you have one of these panels?
Photograph the label and the breaker faces with the cover closed. Then get an opinion from someone licensed — ideally one that is not attached to a quote for the replacement. Tell us what the label says and where the house is, and we will connect you with licensed electrical companies in your area.
HyreElectrical does not perform, supervise or warrant electrical work, and takes no payment for placement, ranking or favorable mention.
This page is research and identification guidance, not advice about a specific property, and nothing on it substitutes for an inspection by a licensed electrician.
We have no commercial relationship with any insurer, panel manufacturer or breaker manufacturer named above, including Connecticut Electric.