Bx armor a neutral?

14 years ago

Hello,

Just bought a house, about 70 years old. Parts of the home have knob and tube wiring. some has been changed to bx quite awhile ago it seems. Today I opened an existing junction box on the closet cieling hoping to add a light. Contained BX with a white and black wire ...both hot and no swtiches to be found. They were just capped off. I hooked the black light wire to the black ...when touching the white light wire to the bx shielding everything worked. Is this a trick they used years back? I've never seen it before. Doesn't seem safe to me but I have no idea. Any help would be appreciated. Thanks

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Comments (5)

petey_racer
14 years ago
NO! It is in fact incredibly UNSAFE. The "BX" in your house is not BX like in newer homes. By this I mean 50's, 60's and 70's homes.

The sheathing is grounded at some point, but it is NOT a grounding conductor.
hexus
14 years ago
" but it is NOT a grounding conductor."

I believe you meant to say it is not to act as the grounded conductor (neutral)
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fixizin
14 years ago
... who thinks a pre-buy home inspection should've caught this? Seriously, you could spot this just by removing the cover of the main/sub panel (or upstream j-box) where this "BX" branch originated.

Buyer and lender were both short-changed by this inspector.
brickeyee
14 years ago
"... who thinks a pre-buy home inspection should've caught this? Seriously, you could spot this just by removing the cover of the main/sub panel (or upstream j-box) where this "BX" branch originated."

Asking a general home inspector to remove the cover frm every j-box and check wiring is well outside the scope of a normal inspection.

They manage to not understand what they are looking at in main panels, let alone other places.

The armor of BX (and AC and MC) are grounding conductors, so anything hooked to a hot and the armor should work.

You are NOT allowed to use a grounding conductor to carry regular circuit currents.

There may be nothing wrong with the wiring, since I doubt the OP tried hooking the light up correctly.

Many things measure as "hot" (especially in old wiring) if a digital meter is used.

Connecting a load from the hot to ground or neutral will often provide a path for the current leakage (and the bulb will not light).
petey_racer
14 years ago
I guess I was a bit vague there.

I did mean grounding conductor. BX from the 30's and 40's did not have the bonding strip and must NOT be used as a ground. Even more important is what Hexus said. It must NEVER be used as a neutral.