BX's took a bit longer, about 8 years for the tail lights, rest to follow by 10 years. I think this a symptom of cheap copper plated steel wiring. Electric current mainly flows on the surface of the wire so the bean counters hit on idea of using copper plate as the surface conductor and very cheap steel wire to support it. Sadly this sets up an electrolytic cell and the steel wire corrodes quite quickly from the exposed cut ends at every connector.
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