This is also known as a "three-prong/two-prong adapter." What is the electrical circuit symbol for this item?

Here is an example:
wikimedia image by user PleaseStand

EDIT: To be clear, I am not using, nor endorsing the use of this device. I am trying to convey that it is being used already by showing where it is in a wiring diagram. I understand that it is not encouraged, and I am not encouraging it either. But it already exists and I need to document it as such in my diagram.

Please restrict comments and responses to potential answers to the original question. Thank you.

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    \$\begingroup\$ Not everything has an electrical symbol, especially an accessory that can be removed and therefore is not really part of anything, and especially especially an accessory like that which should not be used to begin with. \$\endgroup\$
    – DKNguyen
    Commented Jul 23, 2022 at 21:57
  • \$\begingroup\$ What kind of electrical symbol you mean? At least such a component would not be a part of any standard schematic. A wiring diagram maybe. So if it has a symbol, for what type of diagram you need a symbol for? \$\endgroup\$
    – Justme
    Commented Jul 23, 2022 at 22:39
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    \$\begingroup\$ When DKNguyen says this device should not be used, he is right. The reason is that it is easy to install this device and not connect the ring terminal to a normally non-current-conducting ground line at all. Why not? Because the two-prong socket would not be used in any modern installation. If there were a non-current-conducing ground wire present, it would be attached to the ground socket of the three-prong circuit to begin with. And why is this a problem? Because if there is a fault, the fault current will not be conducted to ground and might, instead, be conducted through you. \$\endgroup\$ Commented Jul 23, 2022 at 23:37
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    \$\begingroup\$ This symbol would probably be most appropriate. \$\endgroup\$
    – brhans
    Commented Jul 24, 2022 at 0:28
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    \$\begingroup\$ This is probably the most appropriate, ☠ , U+2620 if it doesn't render for you large enough \$\endgroup\$
    – Neil_UK
    Commented Jul 24, 2022 at 10:35

2 Answers 2


There won't be a standard symbol for that adapter. I've never seen one at any rate.

The thing is that the pictured adapter is not a "cheater" or a "ground lift." It can be misused that way, but that is not its original intent.

The adapter is intended to be used where you have an outlet without a ground pin, but which is grounded.

The metal conduit in which house wiring runs is grounded. The metal junction box in the wall is connected to the conduit. The screw holding the face plate to the outlet goes into the metal frame of the outlet, which is screwed to the junction box.

The result of all that is that the screw on the face plate of the outlet is grounded.

The adapter has a metal tab connected to the ground socket. You remove the screw holding the faceplate, then screw the adapter in place with the faceplate.

The ground pin on the adapter is now properly grounded and safe to use.

Older models had a green wire with a fork (spade) connector. It was more obvious that you were intended to provide a ground connection.

Before using such an adapter, you are supposed to check and make sure that the faceplate screw is grounded. If you don't have a ground for the tab on the adapter then you should not use the adapter.

If you are using such an adapter intentionally without a ground as a "ground lift" or "cheater" then you are using it outside of its intended use - if anyone is killed or injured by that use, it is your fault.

It is unfortunate that such adapters are so commonly known as cheater plugs, as they were not intended for such unsafe use. They were intended to be a safe way to use equipment with three pins in a two pin outlet.


There will be no standardized symbol for a cheater plug, because this will not be used in anything that is planned using plans. If you're using a proper ground adapter (for plugs/outlets that have different, but functional, means of ground connection), then that's essentially just an outlet.

(As you already know, using a cheater plug is somewhere between bad idea and criminally negligent; there's also no symbol for the chemical engineer that signifies "duct tape repair on explosive gas pipe".)

Had I to document a cheater plug (e.g. to prove I'm not the one who installed this in case someone later tries to make me liable for any damage), I'd probably use the usual outlet symbol (depends on the framework/standardization your symbols come from, make two diagonal lines through the line next to it, put a triangular Warning sign next to it and a text box that clearly describes that the user connects a ground-needing device to an ungrounded plug through a cheater plug.

(Seriously, by the way, cheater plugs cannot exist in any wiring plan. For example, in German workplace buildings, that includes offices, kitchens and labs, it's mandatory that in regular intervals, a certified electrician comes through and tests all devices for proper isolation and earthing. This includes extension cords and similar devices. A cheater plug would end up in the "earth connector not reliable" bin, not get the approval, not be allowed to be plugged in (it would have been unplugged by the electrician for testing, either way). The electrician would need to document it in the report that such a device was seen, removed, and not given approval. Plugging the cheater plug back in would be a direct violation of workplace safety regulations and could get you in trouble with your employer.)

  • \$\begingroup\$ I understand, after reading your answer, that the depicted plug is only a cheater plug if abused. I think I should rephrase my answer to be clear about applying to actual cheater plugs, not to ground adapters. \$\endgroup\$ Commented Jul 24, 2022 at 9:22
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    \$\begingroup\$ @JRE is that better? \$\endgroup\$ Commented Jul 24, 2022 at 9:24

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