Most BX is neither safe or acceptable for use as an equipment grounding conductor.
Only BX which includes a bonding wire or bonding strip may be used as ground. Most "BX" style AC cable installed in the 30's-60's does not have the required strip.
Using BX as a ground is extremely dangerous, because it is not a low impedance path to ground. Rather than clearing a fault, the spiral jacket (especially in places where it might have some corrosion) will heat up like a toaster element. I've witnessed this several times. The cable clamps in the original boxes also were not typically listed for use as a grounding electrode conductor. equipment grounding conductor (it was late). -- ...because I care.
Most BX is neither safe or acceptable for use as an equipment grounding conductor.
Only BX which includes a bonding wire or bonding strip may be used as ground. Most "BX" style AC cable installed in the 30's-60's does not have the required strip.
Using BX as a ground is extremely dangerous, because it is not a low impedance path to ground. Rather than clearing a fault, the spiral jacket (especially in places where it might have some corrosion) will heat up like a toaster element. I've witnessed this several times. The cable clamps in the original boxes also were not typically listed for use as a grounding electrode conductor.
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