How can I get ground from a NEMA 5-15R wall socket without electricity?

Question

I have some network equipment that I want to connect to ground (they come with 2-prong wall wart PSUs and have a separate screw hole for a grounding pigtail) - but where would I get ground from in a regular home?

For me, the obvious choice would be an existing wall outlet (regular USA 120V 15A NEMA 5-15R). But I don't need the 120V, I kinda just want to get the ground, connect it to a copper grounding strip or bus bar, and then connect grounding pigtails to that.

If that is sane, then I wonder: How would I get the ground out of the wall socket? I guess I could just jam a banana plug or something into the grounding hole, or cut open a power cable and make sure the +/- electrical plugs aren't connected. But that seems hack-ish and dangerous.

But there also don't seem to be "simple" NEMA 5-15R-ground-taps available (kinda the exact opposite of this), which makes me wonder if a) this approach is actually the correct one and b) whether there might be a much simpler/better way to get ground from somewhere in a regular home. (A non-corrosive steel post outside isn't an option really here, no good way to run a wire into the room)

Answer 1

I have seen adapters that are exactly what you want. On the side that plugs into the wall they have one conductive prong for the earth connection and two plastic dummy prongs to fit the live and neutral. On the other side they present the earth connection either as a single banana socket or a screw terminal.

So they do exist, but I'm not going to try to find a specific part number for you to order because shopping questions are off-topic. Keep hunting and try using "ESD" as a keyword since these are often used to hook up electrostatic discharge prevention equipment.

Answer 2

You have two common options:

1) A plug that is some variation on the left image. They come in many different designs and price points. Be aware that they may also have resistors on some/all of the sockets which could potentially make some unsuitable for your purposes.

2) Use/install a wall plate with an exposed ground screw as shown on the right. You can then simply screw your pig tail(s) to the socket. This should be the cheapest option for you.

Cheaper would be of course to just make your own plug. There are a lot of options as to how you could build one. Personally I would buy a $2 plug with removable type prongs, take out the live and neutral prongs and replace them with plastic. I would 3D print them, but you could use the removed prong as a stencil and just cut a piece of similar thickness plastic into that shape.

Answer 3

The first question you need to ask is what sort of ground do you want and why?

If you want the ground purely for electrostatic discharge protection then ESD grounding equipment is appropriate. ESD grounding equipment contains large resistors to prevent it from passing large currents.

On the other hand if you want the ground for safety* or EMC reasons the ESD grounding equipment will be useless. If what you want is a low impedance safety ground then harper's suggestion of buying a rewirable plug and connecting your wire to the ground terminal is the way to go.

*Either because you don't trust the supposedly class 2 PSUs to actually be class 2 or because you are worried that the leakage currents from multiple PSUs while safe individually could add up to be hazardous.

Answer 4

you're on the right track with safely making use of the ground pin from a standard outlet. I just did the same search within the last couple months and was surprised at how few options there are -- but keep searching and you will find them. I was also surprised at how quickly you can empty your bank account for such a simple device. Follow the advice from pericynthion and search for ESD related hardware. Here is a small collage photo of solutions I investigated. The last image could be easily modified with a banana jack or ring terminal as needed.

Answer 5

• Go to the hardware store and buy a 3-prong NEMA 5-15 plug for $4
• Wire your ground wire to it. Wrap the other terminals with tape.
• Double-check that your receptacle is wired properly
• Profit!