Three-prong to two-prong plug adapter question

[tomkanpa]

I recently purchased some more three-prong to two-prong AC adapters. I know you are supposed remove the screw that holds the face plate on, plug the adapter in, and replace the screw through the "grounding" strap on the adapter. These adapters are also polarized, you can only plug them into the receptacle one way. And when they are plugged in the only way they can be, the "grounding" strap does not line up with the screw. It faces 180 degrees from it. What is the reason for these adapters seemingly not being manufactured correctly?

[Eric in North TX]

Probably a manufacturing error, but if the receptacle has only 2 wires, there is little point to attaching it to the screw anyhow. Most folks keep the adapter with the appliance anyhow.

[professorpaul]

It will line up correctly with ONE of the outlets in the pair. These adapters are designed as an expedient, and not for really permanent setups. If you are going to use 3 prong fittings, the outlets should be replaced accordingly. The problem is that in old installations, there might not be a ground line run, or grouding only through the conduit. Not sure what the code issue is on this.

[Doug Miller]

Plug it into the other half of the duplex outlet.

Operator error.

[David Nebenzahl]

Eric in North TX spake thus:

True that; if you look at 2-wire connections to outlets, the metal frame of the outlet isn't connected to *anything*. The only reason to use that screw would be if you wanted to attach the adapter to the outlet. It serves no electrical or safety function.

[lwasserm]

Are you for real?

[lwasserm]

Actually, IF the wiring is armored cable or IF it is in EMT or other metal conduit, and IF the conduit/metal sheathing is rated for ground use and properly grounded, and IF it is a metal outlet box, then the center screw that holds the cover plate to the outlet WILL be grounded.

[<aemeijers]

Not True. In this 1960 house, the boxes were grounded, via the bond wire being wrapped around the romex under the clamps. No, probably not to current code, but better than nothing. I replaced the 2-hole outlets with

3-hole, and the 15-buck Magic Meter lit up and pronounced them grounded. (Half of them were reversed polarity, and most were worn out, so I had to yank them anyway....) This was old stiff romex with no slack, so I wasn&#39;t about to try to uncoil the third wire to pigtail it to the outlets, and there was no screw hole in the box for a ground wire.

aem sends...

[Seth Goodman]

If you don&#39;t have screw holes in the box, you can use grounding clips that clip onto the edge of the box. You can get a bag of them for a dollar or two at any hardware store.

You can also buy "self-grounding" outlets that are specifically designed to ground through the yoke, though they are somewhat more expensive.

[Doug Miller]

It&#39;s also trivially easy to drill and tap a hole in the back of the box.

[mm]

I think he&#39;s standing on his head.