Zinsco Electrical Panel & GTE-Sylvania-Zinsco Circuit Breakers Failure Mechanisms & Failure Photos

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How & why do Zinsco breakers or electrical panels fail? Here we describe & provide photographs of the apparent failure mechanism involved with Zinsco and GTE-Sylvania-Zinsco electrical panels and circuit breakers. We include field photographs of Zinsco equipment failures from a variety of sources.

This website discusses the electrical, fire, and shock hazards associated with Zinsco electrical components, circuit breakers, electrical panels, including certain Sylvania electrical panels and breakers which are in fact of the same product design and origin. Our page top photo of a burned Zinsco main circuit breaker and burned greased Zinsco electrical panel bus was provided by Washington state electrician J. P. Simmons

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FAILURE MECHANISM - Failure Mechanisms for Zinsco or Zinsco-Sylvania Electric Panels and Circuit Breakers

Zinsco Sylvania panel bus burnup (C) J Simmons D Friedman

Our photo (left, courtesy of J. P. Simmons) shows the typical Zinsco or Zinsco-Sylvania electrical panel main bus damage from arcing.

  • Arcing and/or overheating (see ZINSCO OVERHEAT IR PHOTOS), or a similar failure process occurs at the connection of the circuit breaker to the electrical panel bus damage the bus, the breaker, and the connection, making the electrical contact unreliable and leading to equipment failure.
  • Circuit breakers become damaged by arcing or overheating. Damaged circuit breakers are unlikely to perform properly in response to an overcurrent condition.
  • Aluminum electrical panel components appear to be an important factor in failures in this equipment
  • Moisture exposure appears to be a factor in failures in this equipment.

Types of Zinsco Panel and Circuit Breaker Failures

  • Circuit breakers may fail to trip in response to an overcurrent condition. This is a fire and shock risk.
  • Circuit breakers may "blow out" the side casing of the device in an electrical "arc explosion"
  • Circuit breakers may fail to drop power even when they are switched off [remains to be verified--DF] - that is, the breaker may appear to be switched to the "off" position but internally it may still be conducting power to the circuit.

At OK to USE ZINSCOS? we report on a different viewpoint from a vendor who continues to market this equipment and feels that at its price point in the market this product is reasonable to use, and who opines that when Zinsco equipment fails (burnups, failures to trip) it is because it was "over-used" at too-demanding an amperage draw. Our view is that it is just under that condition that a circuit breaker should trip off.

FAILURE PHOTOGRAPHS - Zinsco Sylvania Electric Panel and Breaker Field Failure Photographs

Clicking on any of the thumbnails at left will display a larger photograph of field failures of Zinsco electrical panel components & circuit breakers.


Zinsco burnup bus (C) D Friedman J Weissman Zinsco burnup bus (C) D Friedman J Weissman

Note: this breaker photo (below) was submitted to us from a purported GTE-Sylvania photograph - it may have been collected from a GTE-Sylvania electrical panel that did not use the Zinsco-design circuit breakers and/or may be of a different brand or manufacture.

At below right is a close-up of the bus-connection portion of a classic Zinsco circuit breaker - showing the difference between these devices.

Zinsco burnup bus (C) D Friedman J Weissman Zinsco circuit breaker close-up showing bus connection (C) Daniel Friedman

Notice: besides the Zinsco & Zinsco-Sylvanial field failures illustrated in this article, additional field failure reports and more photographs of Zinsco circuit breaker failures are found at ZINSCO FAILURE REPORTS



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