Square D, Westinghouse, Cutler-Hammer, I‑T‑E, GE, Federal Pacific, Zinsco: the names on home panels, who started them, who bought whom and when, and who owns them now. Tap any name.
Open almost any electrical panel and you’ll find a name on the door. Many of those names have changed hands several times. This tree follows them, using company histories, catalogs, newspapers and public records. It is history, not a recommendation: IES isn’t affiliated with any of these companies.
How to read it: each line starts the year a company or brand began. Where a line curves into another, it was bought or merged. Lanes group names by who owns them today. Tap or click a name for its story; use the slider to watch the tree grow.
Company or brandOwner along the wayBought or mergedLicense or asset dealProduct line beginsNo longer madeKnown problem panelSwipe sideways to see the whole tree →
Brand details
Every name, in words
The same tree as a list, grouped by who owns each name today. Each entry lists its sources.
Schneider Electric
Today’s home lines: QO and Homeline (Square D brand)
Pittsburgh. George Westinghouse’s electric company was building AC generators by 1886.
Who has it now
Eaton
Line names today
BR
1886 The Westinghouse Electric Company is developing constant-voltage AC generators.
1929 Licenses Square D to make circuit breakers.
Jan. 31, 1994 Eaton completes its purchase of Westinghouse’s Distribution and Control Business Unit, which made Westinghouse’s breakers and loadcenters. Some of its assets went to Thomas & Betts as part of the deal’s antitrust approval.
1995 Eaton combines the product lines; loadcenter production moves to Lincoln, Illinois.
Challenger Electric. We could not confirm its founding date, so we don’t give one.
Who has it now
Eaton (through Westinghouse)
Owner’s lines today
BR and CH loadcenters and breakers
1988 Westinghouse buys Challenger Electric, redesigns the product and moves production from Bridgeport to Jackson, Mississippi. (Eaton’s catalog gives 1988; other accounts say the late 1980s.)
1994 Comes to Eaton with Westinghouse’s distribution business.
Jan. 18, 1897 Founded in Syracuse. The partners started out making electric panel boards, switchboards and Hinds’ own patented switch, then trolley headlights, and later traffic signals and airport lighting.
1981 Becomes part of Cooper Industries.
Nov. 30, 2012 Eaton completes its purchase of Cooper Industries, bringing Crouse-Hinds along.
Not a home breaker-panel brand today; it is here because of its early panelboard history and its place in the Eaton family.
Philadelphia, 1888, Henry B. Cutter’s company. The name stands for “Inverse Time Element,” a breaker trip idea.
Who has it now
Siemens
Owner’s lines today
QP breakers; PN and ES Series load centers
1888 Henry B. Cutter’s company starts in Philadelphia.
1928 Takes the name I-T-E Circuit Breaker Company.
1954 BullDog Electric Products becomes a division of I-T-E.
1968 Merges with Imperial Eastman to form I-T-E Imperial.
1976 Becomes part of Gould.
1983 Gould’s electrical distribution and control business goes to Siemens-Allis, a Siemens and Allis-Chalmers venture; Siemens later owned it outright (reported in 1985).
Federal Pacific Electric’s Stab-Lok panels went into millions of homes from about 1950 to the mid-1980s. We could not confirm a founding date for the company, so we don’t give one.
Who has it now
No longer made
c. 1950–1985 Stab-Lok panels and breakers installed widely in homes.
1979 Reliance Electric acquires Federal Pacific Electric.
1983 The CPSC closes its investigation of FPE breakers (see “Known problem panels” below).
2002 A New Jersey court finds FPE violated that state’s Consumer Fraud Act over its UL labeling (see below).
Two panel families come up again and again in home inspections. Here is only what the sources below document, in plain words. If you have one, it does not mean something is wrong today, but it is worth having a licensed electrician look at it.
Federal Pacific Electric (FPE) Stab-Lok
In June 1980, Reliance Electric, which had bought FPE in 1979, reported to the U.S. Consumer Product Safety Commission (CPSC) that many FPE breakers did not fully meet UL requirements. CPSC testing confirmed that these breakers failed certain UL calibration tests, the tests that check a breaker holds its rated current and trips in time on an overload.
In March 1983 the CPSC closed its investigation. It said the data it had did not establish a serious risk of injury, that it could not link the test failures to a hazard, and that a full study would cost more than it could commit. A note added to that release in 2011 stresses that the CPSC closed the matter without deciding whether the breakers are safe.
On August 15, 2002, in a class action, the Superior Court of New Jersey (Middlesex County) ruled on partial summary judgment that FPE had violated the state’s Consumer Fraud Act by putting UL labels on breakers it knew did not meet UL’s test requirements.
An insurer’s risk guide sums up later testing by the CPSC and independent engineers: certain Stab-Lok breakers did not trip as UL requires and in some cases could jam in the “on” position, and overheating has been found at internal bus connections. It says millions were installed between 1950 and 1985, and it calls replacement the safest course.
An insurer’s loss-control guide describes the problem: each breaker clips onto the bus bar, and over time that connection can lose good contact and arc. The heat can damage the breaker and even keep it from tripping.
Zinsco breaker production stopped in the mid-1970s, so these panels are now decades old. The same guide says damage is not always visible and recommends an inspection by a licensed electrician.
What to do: don’t open the panel yourself. Have a licensed electrician evaluate it. They can check for heat damage, loose breakers and wear, and explain your options, which can range from leaving it alone to replacing it.
Use the breakers the panel’s label lists. Each panel has a label (usually inside the door) naming the breaker types it was tested with. The electrical code says listed equipment must be installed and used following its listing and labeling instructions.
“It fits” is not the same as “it’s approved.” A breaker from another line can snap onto a bus and still not be a tested match.
Classified replacement breakers exist. UL has a separate “Classified” category for breakers made to go in certain panels from other makers. Each one comes with a compatibility list naming the exact panel catalog numbers, and is limited to 120/240-volt panels where the available fault current is no more than 10,000 amps.
We don’t list which brands fit which panels here. Those lists change and depend on exact catalog numbers. An electrician can match the label to the right breaker.
We used company histories, product catalogs, newspaper archives, SEC and trademark records, the National Register of Historic Places, safety agencies and insurers’ risk guides, and we link them on every entry. Corporate family trees are messy: names get licensed, divisions get sold in pieces, and dates differ between an agreement and a closing. Where sources disagree, we show both or leave it out. Brand names belong to their owners; we use plain text, not logos. Spot a mistake? Let us know.
What we left out or softened
Murray’s pre-Siemens ownership path (sources disagree or are weak): left out.
A claimed Zinsco-to-Challenger link: left out.
Federal Pacific Electric’s founding date: not given.
Challenger’s founding date: not given; the Westinghouse purchase is shown as 1988 per Eaton’s catalog.
Cutler-Hammer to Eaton: shown as 1978–1979 (agreement vs. completion in different sources).
Square D’s first home breaker: 1930 (Schneider catalog) and 1935 (encyclopedia) both shown.
Westinghouse founding: worded as “by 1886” from ETHW, not a founding date.
Lutron’s 1959 patent is not called solid-state (it describes a diode and autotransformer).
Brand-to-panel breaker compatibility: not listed at all.
Westinghouse profile: no founding date for the company; it is worded as “by 1886.”
Federal Pacific profile: founding date and founders not given (not verified).
Zinsco profile: early family history is labeled as a family member’s account.
Murray, Pass & Seymour / Legrand and Kohler: not profiled (not verified well enough yet).
Powerwall 2’s 2016 unveiling: left out (only secondary sources); Tesla’s own 2017 production date is used.
Generac’s “first automatic home standby generator” (1989) is shown as Generac’s own claim.
Zinsco’s origin: told as a family member’s account, not as settled fact.
Lutron ownership: “privately held and family-run” is stated as of the 2015 reports, not as a current fact.
End dates for Federal Pacific and Zinsco are shown as “mid-1980s” and “mid-1970s,” as the sources word them; the line ends in the chart are approximate.
Murray’s end: Siemens describes phasing out the brand over 2019–2020; no single date is given.