You Should Replace Obsolete Main Service Panels

"What?  I have to replace my main electrical service panel when installing a solar system?" exclaimed the homeowner.

We visited a home the other week to conduct a solar evaluation and found that the main electrical service panel needed replacement.  The homeowner was surprised!  Most people believe such an important part of a house would generally be reliable for a very long time.

We found the house had an obsolete electrical panel.  There have been lots of articles published about the safety of these panels but when it comes to installing a solar photovoltaic system in the house, why take any chances of problems?

The first bad boy is a panel made by Zinsco, who have been making panels since the early 1930s.

Zinsco electrical equipment is considered obsolete, due to a design flaw in which the circuit breaker's connection to the bus bar becomes loose, causing arcing and subsequent overheating. Long term exposure to this heat can cause the breaker to fuse to the bus bar, making it impossible to remove. Even worse, it can cause the breaker's contacts to fuse together, thus preventing the breaker from tripping even in an over current situation, thereby causing a potential fire hazard.

Zinsco sold to GTE-Sylvania who kept the design and continued to make panels and circuit breakers under the GTE-Sylvania brand.

zinsco circuit breakers
Federal Pacific Electrical Panel

The second panel to avoid is made by Federal Pacific and it has a brand name of Stab-Lok. Known to start fires, it is recommended that you replace these panels, even if you don’t install solar.

Inspectapedia, (the Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair) states:

Federal Pacific Electric "Stab-Lok® " service panels and breakers are a latent hazard and FPE circuit breakers can fail to trip in response to overcurrent, leading to electrical fires. The breakers may also fail to shut off internally even if the toggle is switched to "off." Some double-pole (240-Volt) FPE circuit breakers and single-pole FPE Stab-Lok® circuit breakers simply do not work safely.

There are other FPE panel-defects independent of the breaker problems, panel and panel-bus fires and arcing failures in some equipment. The failure rates for these circuit breakers were and still are significant. In some cases failure to trip occurs 60% of the time - a serious fire and electrical shock hazard.

You can read the whole Inspectapedia report here.

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