220 recepticle with 110 current to metal box
 

Today I wired a single-phase 20 amp 220V 3-blade receptacle. After testing as expected, I got 220 V when both hot receptacle slots were tested. Also got 110 Volt from the ground receptacle slot to each of the hot wires slots individually. I have a metal receptacle box and happened to notice it registers 110 V when I touch a single hot receptacle slot and the metal box. I thought this odd since my ground is insulated and not a bare cooper wire. Is this normal? Does the female receptacle ground to the metal box? (no neutral was wired)

Yes this is normal if you grounded the box properly. The ground is to give you a low impedance path back to your panel so the breaker will trip if there is a short to ground, and so your body would be a higher impedance and not go back through you. :thumbsup:

Thanks. I wouldn't have noticed except I just happend to touch the box while testing. Appreicate the info.

All metal boxes should have a ground pigtail from the device (receptacle) to the metal box. There will be a 10/32 threaded hole in the box. Take a green or bare wire and a green grounding screw from this connection point to the grounded terminal of the receptacle. Yes, is the answer to your question.

Note: There are exceptions to this rule. But to be on the safe side, just install the jumper.