tymish

Well, some minor diffence of opinions. Seems like without a bonding wire if the sheaths get pulled apart into a spiral or there's a poor connection with a lot of resistance it becomes like a toaster element if there's a short from hot to the sheath and a breaker fails. Guess I'll put a load circuit analyzer and at least get some impedance/resistance numbers for the ground and check for weak connections in the old wiring and install those GFCI/AFCI breakers. I found this info on another board so I'm quoting someone else. Appears to be as accurate a reason as I could find. So since there grounded outluts on the old BX are not to code do I need to replace with 2 prong or label the three prong GFCI-No equipmanent grouind?

Okay thanks for the reply. Looks like there are a couple GFCI outlets installed in the bath and kitchen. What about installing combo AFCI/GFCI breakers and keeping the 3 prong outlets grounded to the boxes? Maybe the ground may not be ideal but would the AFCI/GFCI breakers cover safety issues?

Have a house built in 1939 with the original armored cable wiring. The breaker box is relatively new Square D. Everything looks to be wired tight to the box as far as the sheaths etc. Recently someone installed 3 prong receptacles in a lot of outlets and grounded with wires screwed to the boxes. Testing with a pocket LED tester looked OK. Haven't had a chance to test with a meter yet. From what I've read it may or may not be OK to use the boxes/sheaths for ground. Can't tell yet if there's a bonding wire in the cable. Any ideas? Would replacing the breakers with GFCI breakers and keeping the grounds wired to the boxes work?