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Zinsco Electrical Panel & GTE-Sylvania-Zinsco Circuit Breaker Failure Reports
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Zinsco or GTE Sylvania Panel Failure Reports:

This article describes field failure reports of Zinsco or Sylvania-Zinsco or Kearney electrical panels: overheating, failure to trip, fires, other defects.

We [J Simmons] see damage in about 25% of the Zinsco/Sylvania panels that are checked. The problem occurs mostly on circuit breakers feeding circuits that have a steady heavy load on them (like heaters, hot water tank, dryer), and on circuits that are often overloaded such as circuits that supply the kitchen or bathroom.

In houses with Zinsco/Sylvania electrical panels and circuit breakers, I [Simmons] have tested these circuits with up to 30 amps on a 20 amp circuit breaker.



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Zinsco® & Sylvania Electrical Panel Field Failure Reports

The Zinsco circuit breaker will carry the overload for a long time without tripping. This causes the connection to heat up and start arcing to the buss bar. The problem is primarily in the panels with aluminum buss bars, but also has been seen in the ones with copper buss. Moisture seems to accelerate the process.

Zinsco main breaker failure (C) J Simmons D Friedman

The following anecdotal reports describe observations of failures in Zinsco and Zinsco-Sylvania electrical panels, buses, circuit breakers.

Since most home owners and electricians are more focused on immediate electrical repair and safety needs than in taking photographs and writing failure reports, our opinion is that number and frequency of these electrical failure field reports are the "tip of the iceberg" of actual occurrence.

(Above, the photo of a burned Zinsco main circuit breaker and burned greased Zinsco electrical panel bus was provided by Washington state electrician J. P. Simmons)

We estimate that only 2% to 5% of electrical failures are recognized and reported to the U.S. CPSC or to researchers such as Daniel Friedman or Jess Aronstein. This opinion is supported by a US CPSC study of failed electrical receptacles.(1).

  1. 05/09/2010 - Stanford CA: Zinsco field failure report: blinking lights, loose Zinsco breakers, corrosion, arcing main breaker connectors:
  2. Zinsco panel sketch (C) D Friedman JH 2010

    I could hear arcing and my lights were blinking, so I reset all the breakers. Many of the breakers were loose, so I pulled them and tighten the clips. The problem continued, so finally I pulled the "main" breaker (125 amp) to find corrosion and arcing on the crossbars.

    The question is whether this box can be retrofitted as you suggest on your website, or will I need to replace the whole panel.

    My Zinsco panel is aligned vertically (~30" tall by 14" wide) [Drawing at left, provided by the owner.]

    The top third contains the breakers arranged horizontally on parallel aluminum crossbars; the middle third had the service meter; and the lower third is enclosed so I guess it covers the supply wiring from the street.

    Also, the panel is outside on an exterior wall, installed around 1967.

    - Jerry

  3. 03/25/2010 - Opinion: Milestone Electric, Dallas: owner Gus Anton reports during our discussion of FPE, Zinsco, & Aluminum wiring that in his company's experience, they find the need to replace more Zinsco electrical panels than other brands in that city. - personal communication, GA to DF 3/25/2010. Also see Zinsco_Class for Electricians - Summary for licensed electricians, requested and sponsored by this company.
  4. 02/19/2008 - J.P. Simmons: Just got these pictures [more photos were provided and are on file] of a badly damaged Zinsco main that failed. In this case the failure damaged the main wire to a mobile home also (you can see the melted wire to the left of the main). This is a good example of why I do not like to see anyone remove these breakers. You can not tell how bad they are damaged by looking at them.
  5. Zinsco no trip wiring burnup (C) D Friedman J Shuma

    2/20/2007 - Jim Shuma Zinsco no-trip, wiring burn-up report: I had some wiring burn through in my home.

    The circuit was overloaded, but the Zinsco panel didn't trip.

    Note the burned insulation, the burned outlet cover, and the wire that burned through. (See photo at left).
  6. Zinsco main no trip, wiring burnup (C) Daniel Friedman J  Bolton
    03/06/2007 Zinsco Main No-Trip, wire burn-up report, Jon Bolton, a professional home inspector in central Florida (see photo at left).

    Notice the burned wires connected to the bottom double-pole Zinsco circuit breaker?

    At ZINSCO OVERHEAT IR PHOTOS we provide additional photographs of this Zinsco no-trip overheating failure documented by Mr. Bolton. Mr. Bolton wrote:

    I have done 2 inspections in this complex, ironically (or not)  both had issues.  One had a complete side blow out.  Sent a letter to management, no response, hmmmm.

  7. 01-08-2006 06:59 PM -- Since I started this, now I'll put in my 2 cents. I am a master electrician (obtained license while still working in the field), a certified electrical inspector and a CBO. I'm with Ryan! And I have a FPE panel in my bedroom closet (oops, Ryan just disclaimed me). PG and Tanky, do you really think you can condemn my house for having a old panel??

    My parents house has a Zinsco from the 50s, split bus. You're gonna go after mine in a closet but say their's is OK because its in the garage (with paper files stacked around it). I think a change out should be allowed to stay in the closet, but with so many people having concerns, maybe I should find a way to CYA or at least strongly encourage the HO to move his panel.

    One thing to think about is how many homes have panels in garages and have cardboard boxes stacked around it and in front of it. That's a violation but we don't require the garage floor to be marked "no combustibles in this area". (Oops again, I probably gave someone an idea.) Thanks to everyone for participating, but if you're gonna zing somebody, do it backhanded with sarcasm, its funnier than the in your face stuff.

    From: garland, TX (near Dallas) | Registered: Jan 2005 http://www.iccsafe.org/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=11;t=000888
    01-09-2006 02:36 AM -- jboren, Yes I could and would condemn your home if I knew it was a fire or safety hazard. I believe if your parents service was a fire hazard you would have already fixed it. There are way too many government dollars available out there for someone to use the excuse it cost too much.
    [DF NOTE: This is from the ICC bulletin board - ICC is the International Code Council]
  8. May 04, 2005 - Susan R. Olympia, WA: Customer called to have a burnt up outlet in their bathroom repaired. When I arrived on site I found the outlet completely burnt up, and the wiring badly damaged. The circuit was 12 gauge on a 20 amp Zinsco breaker.

    After some tracing I found the circuit also had kitchen outlets on it. The refrigerator and microwave they were using added up to 20 amps exactly, but they also had 2 bathroom outlets and lights on the same circuit. The owner had two portable heaters they used for the bathroom and bedroom area, and also used the typical hair dryer and curling iron, all on the same circuit! I asked the owner if the circuit ever tripped and she said that it had when she used the hair dryer while the heater was on, and the microwave was being used at the same time.

    This would be at least 36 amps on a 20 amp circuit! They did not have a problem using the smaller heater (1000 watts) and the microwave and hair dryer at the same time (about 30 amps), or when using the larger heater and the microwave at the same time. - Jim P. Simmons
  9. January 28, 2005 - Zinsco panel, meter clip short circuits to panel?? Dear Mr. Friedman, Have you ever run into a situation with an 70's era Zinsco panel wherein upon removal of the panel face cover, the meter can be moved in such a manner that the lower meter clip contacts short to the panel housing. I have recently seen a panel with this condition and was wondering if this is a known problem with some Zinsco panels. Thanks, - Phil
  10. 3-21-2004 Kory

    I am a 12 year veteran electrician with a new business in hand. I am seeking hard data on the Zinsco and FPE panels, I have a few personal experiences that make me personally aware of the dangers these brands but sound to a customer as self serving when I make my warning "I would consider replacing that panel as soon as possible".

    Most consumers look at the panel as something that has existed for many years without harm and I feel consider my words as money making. Truth is even if they choose another contractor I still want them to be better informed!

    Any direction you could pass to me would be appreciated. I have spent many hours searching the web and seem to find forum type input more then hard fact

  11. 9-2-2003 Split Bus Zinsco: Thought you might like to see some more Zinsco panel damage pictures. I have this panel in my possession. This panel was badly damaged in the whole top section (above the sub main) where it is not possible to shut the power of because it is a split-buss panel with no main breaker. The really scary part is the customer did not know they had a problem.

    I was at the site to do an estimate and noticed the Zinsco panel. I asked the customer if it was alright to check it for him, and he agreed. He said the only trouble he knew about was the water heater didn't always give them real hot water. I pulled the panel cover off and everything looked OK. I checked the breakers with a volt meter and had proper voltage at all the circuits.

    Then I started (carefully) removing breakers and found the top (water heater circuit) breaker had welded itself to the buss and came apart when I tried to remove it (this could be very dangerous for a homeowner or home inspector). I removed several other breakers and found them to be badly damaged, and the bussing was burnt in several locations. After seeing the situation it was not hard to convince the owner that it was time to replace the Zinsco panel. -- J Simmons
  12. 8-29-2003 Zinsco: Thought you might like to see some more Zinsco panel damage pictures. I have this panel in my possession. This panel was badly damaged in the whole top section (above the sub main) where it is not possible to shut the power of because it is a split-buss panel with no main breaker. The really scary part is the customer did not know they had a problem.

  13. May 15, 2003 - Zinsco/Sylvania breakers and panels - Dan P. Olympia, WA

    I was asked to look at this customer's home to give them an estimate to replace a Zinsco/Sylvania panel. The panel is the split buss type 200-amp with no main breaker. The panel looked OK but when I removed some of the breakers to check the bussing I found that the 100-amp 2-pole that fed to his shop had signs of degradation on the buss. The 2-pole 30-amp breaker next to it also had started deteriorating. They had not failed yet or caused the customer any noticeable problems.

    I then tried to remove the 60-amp 2-pole sub feed breaker (it feeds the bottom section of a split buss type panel) and it would not come out. I went to my truck and got my large screwdriver to use (carefully because there is no way to shut off the power to it) as a prey bar. I tried to remove it again and the breaker was welded onto the buss so bad that the buss started to come out with the breaker.

    I pushed the breaker and buss back into place and let the customer know that he had a serious problem that needed to be addressed as soon as possible. I will get him a price to replace the panel ASAP.
    Pictures 1,3 ,5,6 are of this panel. - Jim Simmons

  14. April 25, 2003 - Ken W., Olympia, WA - Lacey, WA

    We had recently removed a Zinsco panel that was causing some problems for Ken Woehl. The bussing was damaged in a couple places (the problem was identified on a home inspection that I did for him) where the breakers plugged onto it. We got a call from our customer today about a problem he was having with the new Cutler Hammer panel we just installed for him (to replace the Zinsco).

    His complaint was when he ran his furnace and his microwave at the same time the circuit tripped. He said the breaker never tripped before (when the Zinsco panel was in place). Code requires the furnace to be on a separate circuit, but evidently the wiring had been altered so the kitchen microwave was on the same circuit. The circuit load with the furnace and microwave both on was over 26 amps.

    Now that we installed a good quality circuit breaker panel the breakers are doing what they should - shutting off when there is an overload and protecting the house. The Zinsco panel has bussing damage in it caused by a circuit that was overloaded for a long period without the circuit tripping. I have this panel in my possession for confirmation and the pictures here are from this site. - Jim Simmons
    Zinsco failure photo Photo 8: A Zinsco main panel,

    and GTE Sylvania Zinsco failure photo Photo 9: A Zinsco burned circuit breaker. - updated by J Simmons 3/8/2006

  15. 4/15/03 - Black Lake Park - - Re: Zinsco Breakers: I was called out to bid a job for the Black Lake Community Park. I checked the panel for circuit capacity and noticed it was a Zinsco brand. I asked the customer if it was OK if I checked it, and proceeded to pull the cover off. The breakers and panel looked to be in great shape. No obvious heat damage or signs of conductor damage.

    I proceeded to pull off the breakers and found the top 3 - 30 amp breakers all had serious damage to the breaker and the bussing. One was so bad that the part of the breaker that pushes onto the bussing had become welded to the buss. The breaker actually broke apart (with the connection staying on the buss and the rest of the breaker coming out) when I tried to remove it. The panel did not have a main breaker (split buss type) so there was no way to shut off power to the top (main) section.

    This could be extremely dangerous if a homeowner, or a home inspector had tried to remove the breaker to replace it, or check it. (I have this panel in my possession because they had us change it). -- Jim Simmons

  16. 3/22/03 - May G. Olympia, WA

    Re: Zinsco Split Buss Panel, about 40 years old: On 3/22/03 I went out on an emergency call - The customers friend was removing baseboard electric heaters for her that were no longer needed (she had a gas furnace installed). He turned off the circuit breaker that was marked "Main" and proceeded to cut the wires loose on the heaters.

    He thought he had the power off, the only problem was this panel was a older type that did not have a main. It is called a split buss type panel (it does not have a main breaker) and you have to turn off all the breakers to kill all of the power. He proceeded to cut the wires from the back of the baseboard heaters, and shorted out one circuit when he cut it.

    He had bright flash and loud bang which scared him so bad he dropped his wire cutters. He went to the panel expecting to find a circuit breaker tripped, but and none were tripped. He was concerned so he called us for some expert advice. I confirmed that none of the breakers had tripped even though he had shorted across a 240 volt circuit!. We recommended that they change the panel to a new one to get rid of the Zinsco panel.

    Unfortunately this is not a isolated incident. The circuit breakers are very poor quality and do not provide a safe level of over current or short circuit protection. - Jim Simmons

  17. March 2003 - John A., Seattle WA:

    This message is in response to your request for descriptions of problems with Zinsco electrical panels. Our panel (in a 1922 Seattle house) was installed in December 1960, based on the city inspection tag we found stuffed into the wiring.

    In early March 2003, on a day when we were about to leave the country on vacation, we noticed that some of the incandescent lights in our living room were flickering slightly. At the same time, we heard the squeal of the UPS that protects the computers in our home office (a noise it makes when it detects bad power). It was a very windy day, and we attributed the problem to a tree branch hitting a wire. We shut off the UPS and left on our vacation.

    Upon returning, we discovered that the circuit for those areas of the house was completely dead. The circuit breaker had not tripped, but it had failed and no power was being delivered to that circuit. Resetting the breaker had no effect (although it did cause a sizzling noise and, after the panel cover was removed, a visible sparking).

    We called an electrician to fix the problem, and he filled us in on the Zinsco problems. we have one other circuit with a flickering incandescent light (all other lights on the circuit are fluorescent, and don't show the flickering), and we suspect that the problem is another bad breaker. We are currently in the process of having the entire panel replaced.

  18. The citations below are representative of comments observed at Mike Holt's Page on Zinsco Breakers - http://www.mikeholt.com/forum/Forum1/HTML/005092.html as of 3/8/2006. Holt's page contains additional information. Emails were deleted from the text here for privacy.
    Also see FLICKERING LIGHT DIAGNOSIS - causes of flickering or dimming lights

  19. December 28, 2002 - Don Walker, Location: Georgia, Electrician: In Trade Since: 1982, Registered: Dec 2002, here's the situation.... customer complained that breaker would not trip...5 year old stuck a fork in receptacle ....sparked for several minutes...had to take broom handle and knock fork out of receptacle. heard a lot of negative about Zinsco breakers ...should I... tell customer to manually turn each breaker on and off several times (once a year) replace all breakers with new Zinsco ...replace Zinsco panel(200 amp) with a more name brand (square d...Siemens...etc) house has all aluminum wiring.
  20. December 28, 2002 - Name: Tim Hausmann Location: Illinois Title: Electrician In Trade Since: 1982 Registered: Apr 2002 -- Once saw a Zinsco breaker not trip when my amp probe showed 34 amps being pulled. Scared the hell out of me. By the way, it was a 15 amp breaker.
  21. December 29, 2002 - Name: Allen Wayne, Location: Florida, Title: Electrician In Trade Since: 1975 -- I haven't seen many Zinsco breakers recently but just like a stab lock fpe you can almost arc weld with them,Home depot sells a replacement for them about $25 a single pole breaker.It would be more cost efficient to just replace them with an available and affordable breaker/panel
  22. December 30, 2002 - Name: Todd Yetter Location: Delaware Title: Electrician In Trade Since: 1988 -- Has anyone ever seen the Zinsco breakers that don't have a set screw on the terminal lug? just a pressure terminal like on the back of stereo equipment

    RESPONSE: Paul W. Location: Washington Title: Electrician In Trade Since: 1991 -- Has anyone ever seen the Zinsco breakers that don't have a set screw on the terminal lug? just a pressure terminal like on the back of stereo equipment? Yes, I have.

    They have a tab underneath where the wire stabs in, to release the wire from the breaker. Note that there is a reason that UL pulled their listing from Zinsco breakers....THEY DON'T TRIP!!! FPE also has the same problem. Bulldog Push-o-matic's, I believe, also have the same problem. But hey, on the plus side you don't have to deal with any nuisance tripping, either
  23. Submissions of Zinsco or other electrical component field failure reports and failure photographs wanted. Contact Us with field reports and photos. We are pleased to credit and link-to contributors.

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Or see ZINSCO CIRCUIT BREAKER TEST REPORT for a summary of Zinsco and UBI-Zinsco-Replacement circuit breaker test results to date.

Or see ZINSCO FAILURE REPORT PROCEDURE to homeowners when a Zinsco Sylvania electrical panel is observed by a contractor, home inspector, or electrician.

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Zinsco Electrical Panel Article Series

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