Zinsco Panels
- Thread starter augie47
- Start date
- Status
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
The connection of the breakers to the bus was problematic and the breakers tended to not trip when they needed to. The bus is aluminum and the breaker clips can corrode, then arc. Or if the breaker fails to trip, the clips can fuse to the bus and the entire panel would have to be replaced.
Other than that Mrs. Lincoln, I thought the play was lovely…
Other than that Mrs. Lincoln, I thought the play was lovely…
ramsy
NoFixNoPay Electric
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
In my experience residential Zinsco end-of-life is typical to most UL-tested equipment.
* Breakers found to fail in open position
* Handle not indicating trip position
* Non-copper bus contacts pitted or burnt with dissimilar alloys at breaker contacts.
* Lasts forever if well cleaned & maintained
Also typical with first generation circuit breakers, was more extensive wiring damage & burned up boxes, before magnetic trip function was added.
I believe Mag Trip breakers became available for Zinsco by the 1970's
* Breakers found to fail in open position
* Handle not indicating trip position
* Non-copper bus contacts pitted or burnt with dissimilar alloys at breaker contacts.
* Lasts forever if well cleaned & maintained
Also typical with first generation circuit breakers, was more extensive wiring damage & burned up boxes, before magnetic trip function was added.
I believe Mag Trip breakers became available for Zinsco by the 1970's
Old Zinsco plug in panels had plated copper buss bars, the aluminum buss in later panels was more problematic, but considering they were obsolete by the early 1980's means the time to replace them was even before the panel was removed from the factory packaging.
The original Zinsco were additionally branded as "Magnetrip", (1950's to 1960's)
ramsy
NoFixNoPay Electric
- Location
- LA basin, CA
- Occupation
- Service Electrician 2020 NEC
Does that mean Thermal-Magnetic breakers were around since the 1950's?
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Since at least then.
I believe ITE introduced them in the 30s, the Square D MO series were thermal magnetic back in the 40s.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Today’s electrical history lesson:
ITE stood for “Inverse Time Element”, the concept of a “thermal” trip whereby the trip action acts faster as the current increases, ie the trip curve is the inverse of the current curve. The ITE element dates back to the late 1800s used by a company called Cutter Electric (not Cutler) in Philadelphia who eventually renamed themselves to ITE because it was so popular. But that ITE element was a “dash pot” mechanism (oil in a sealed chamber) and was thermal only.
The “Thermal-Magnetic” trip came along in the mid 1920s from a German electrical contractor named Hugo Stotz, who sold his contracting business to Brown Boveri (who eventually became ABB) so that he could pursue his dream to invent a way to get rid of fuses. He combined a bi-metal strip to mimic the dash pot ITE action, with a magnetic plunger to trip instantly on a short circuit. He sold his patent to BBC as well, called the Stotz Circuit Breaker, which was made in the same case as a fuse so that it could directly replace them. BBC had a patent in the US as well, but since BBC didn’t market much here, the Thermal-Mag breaker concept didn’t take off until that patent expired in 1940. That’s why you don’t see T-M breakers older than that here. Once the BBC patent expired, everybody got on the T-M bandwagon, including ITE.
Side note on Hugo Stotz, although he did not invent the neon lighting tube, he was the first to make it into an electric sign, for his contracting business in Mannheim Germany.
ITE stood for “Inverse Time Element”, the concept of a “thermal” trip whereby the trip action acts faster as the current increases, ie the trip curve is the inverse of the current curve. The ITE element dates back to the late 1800s used by a company called Cutter Electric (not Cutler) in Philadelphia who eventually renamed themselves to ITE because it was so popular. But that ITE element was a “dash pot” mechanism (oil in a sealed chamber) and was thermal only.
The “Thermal-Magnetic” trip came along in the mid 1920s from a German electrical contractor named Hugo Stotz, who sold his contracting business to Brown Boveri (who eventually became ABB) so that he could pursue his dream to invent a way to get rid of fuses. He combined a bi-metal strip to mimic the dash pot ITE action, with a magnetic plunger to trip instantly on a short circuit. He sold his patent to BBC as well, called the Stotz Circuit Breaker, which was made in the same case as a fuse so that it could directly replace them. BBC had a patent in the US as well, but since BBC didn’t market much here, the Thermal-Mag breaker concept didn’t take off until that patent expired in 1940. That’s why you don’t see T-M breakers older than that here. Once the BBC patent expired, everybody got on the T-M bandwagon, including ITE.
Side note on Hugo Stotz, although he did not invent the neon lighting tube, he was the first to make it into an electric sign, for his contracting business in Mannheim Germany.
Interesting, thanks! When did the hydraulic magnetic breakers come around? Was heinneman (sp?) the first to make those?
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Yes, Heinemann invented the magnetic-hydraulic breaker in the late 1920s in response to the ITE breakers being sensitive to ambient heat. The Heinemann breaker is not thermal at all, the trip is based on magnetic field strength, dampened by a hydraulic cylinder. They are still used a lot in shipboard and aircraft applications because of being ambient insensitive. I built some panels for a yacht once, all Heinemann for the breakers. They were super expensive and I had to know why they were insisting on them. It was because in the tropics, the engine room where this was going gets super hot and you don’t want breakers nuisance tripping, leaving you with no power. Made sense.
we also see hydraulic magnetic breakers on portable power distribution used in film&television. They like to be able to pull 20 amps all day long from a 20 amp circuit who's breaker is in a black box sitting on black asphalt baking in the sun.
What is interesting is Gould Inc. sold a division of ITE to the then Brown Boveri Electric, when they were divesting of most of what was ITE Imperial Corp., the only division they kept was the Shawmut fuse div. (Formerly Chase-Shawmut)
- Status