I am replacing my old dishwasher which was hardwired but the problem is that the old wiring is just Hot, Neutral, and Bx cable therefore there is no reliable ground. THe new dishwasher comes with a 3 prong cable so i need to install a new outlet but my concern is the grounding. Some one please tell me what to do. can i get grounding from the nearest outlet which is about 4 fee above the one that im am trying to install.
Actually, it is code that a dishwasher must be hard-wired. It calls for a separate 20-amp circuit. I would suggest removing all the old BX cable for your dishwasher circuit, and replacing it with 12-2 romex, all the way back to the panel in the basement. The cord does not need to be installed, and can easily be removed and the junction box converted to a hard-wire box. Use a romex clamp and orange wirenuts to connect the 12-2 wires to the dishwasher wires. Black-to-black, white-to-white. Connect the ground wire to the green ground terminal. If the breaker was 15-amp, replace it with a 20-amp of the same brand.
If you use a metal clamp type connector in a metal box the outer casing of the BX will serve as a ground. Not to current code but if that is all that is available it will have to do. Use a continuity tester and see if you get a reading from the neutral to the casing. If so you have a ground path that you can use to ground the box. Then you install a ground wire to the back of the box and attach it to the receptacle. By code this receptacle should be a Single not duplex type. If not try the same thing at the other box. If you get a reading there fish a wire down to the new box. Other wise install a polarized 2 prong receptacle. Use copper pipe to connect the plumbing not plastic
