brycenesbitt
Senior Member
- Location
- United States
I was asked to inspect because the CFL's blew up. The HO reported the lights had been flickering for days.
Sure enough, the meter showed 240 volts on the nearest receptacle. The open neutral was easy to find: it was the one with the melted insulation and that sort of brightly colored oxidized copper color. It snapped on touch, before I could take any measurements.
But here's the part I am confused about. This was a multiwire branch circuit with a common neutral. The two breakers were untied and on the same phase. That could account for the melted wire, especially since the neutrals in the panel were all shoddily installed and loose. 15 amp + 15 amp is 30 amp onto a 14 gauge wire.
---
But one of those breakers was tripped.
So where could the 240 volts have come from? What was the circuit path?
--
Background:
House was built 1935. The problem feed left the subpanel on bx cable, and disappeared into a closet, reappearing on the knob & tube running all the interior lights plus most of the outlets. The HO reports the closet used to hold a fuse box. But if so, could there have been only two fuses? Would four or six not have been more common?
The K&T had been hacked to death throughout the house: extension cord quality wires hand wrapped onto the k&t, a section of k&t wire removed and run through an empty section of bx during a remodel, dangling chopped circuits, failed vinyl electrical tape patches everywhere, and a particularly nice added ground wire thoughtfully connected to a 3 food section of copper water pipe dangling in mid air.
The original K&T, of course, was in perfect condition. Though I did find an 1935 error: one missing tube, and a period "hack" to provide a replacement with wire sheathing.
Sure enough, the meter showed 240 volts on the nearest receptacle. The open neutral was easy to find: it was the one with the melted insulation and that sort of brightly colored oxidized copper color. It snapped on touch, before I could take any measurements.
But here's the part I am confused about. This was a multiwire branch circuit with a common neutral. The two breakers were untied and on the same phase. That could account for the melted wire, especially since the neutrals in the panel were all shoddily installed and loose. 15 amp + 15 amp is 30 amp onto a 14 gauge wire.
---
But one of those breakers was tripped.
So where could the 240 volts have come from? What was the circuit path?
--
Background:
House was built 1935. The problem feed left the subpanel on bx cable, and disappeared into a closet, reappearing on the knob & tube running all the interior lights plus most of the outlets. The HO reports the closet used to hold a fuse box. But if so, could there have been only two fuses? Would four or six not have been more common?
The K&T had been hacked to death throughout the house: extension cord quality wires hand wrapped onto the k&t, a section of k&t wire removed and run through an empty section of bx during a remodel, dangling chopped circuits, failed vinyl electrical tape patches everywhere, and a particularly nice added ground wire thoughtfully connected to a 3 food section of copper water pipe dangling in mid air.
The original K&T, of course, was in perfect condition. Though I did find an 1935 error: one missing tube, and a period "hack" to provide a replacement with wire sheathing.