Have a shorted section of Bx, melted anti short bushing. Was the connection of new romex wiring to old knob and tube lighting and replaced base board outlets. The white wires had the insulation melted together and thats why there is a spot where the white conductor has a hole in insulation.....this was found as a result of circuit not working and shorted after a space heater shut off power in adjacent breaker. but this one circuit could not be reset...looks like the return wire could have been melted through at bx jacket and anti-short was not doing its job. I believe this install has been like this for 6+ years, Would all the new base board boxes be subject to damaged romex.... there is not enough connected load to cause overload under normal conditions.
