Quick question for you guys,

This question is for a home that was built in the 1970's and uses AC cable. I know that the cable armor functions as the ground and works just fine as long as it is clamped down properly. It appears that back in the 70's when they installed all of the original outlets they did not use any ground wires to ground the outlets to the electrical boxes themselves. I assume this is because the screws holding the outlets complete a ground path into the box, which is bonded to the AC cable armor. Is this method still acceptable? If I install a new outlet, or GFCI for that matter, do I have to do anything to ground it, or are the screws holding the outlet enough? :confused: Somehow I think I already know the answer, but the 1970s electrical boxes don't have grounding screws, so clamps would be needed I assume..?

There are receptacles and other devices that are rated to be grounded by the two supporting screws, called "Self Grounding", see this for example:

http://assets.twacomm.com/assets/pdf/14935.pdf.

These do not require a jumper to connect the green screw on the device to the metal box.

If the device you have is not rated "Self Grounding" then a jumper is needed to connect the device to the box. You can find premade jumpers in the electrical dept of hardware stores, 6 inch or so, #14 and #12, with a green screw to attach to the metal box.