How to properly ground computer equipment when I only have 2-prong outlets?

January 5, 2004 8:10 PM

Is there any way to properly ground computer equipment when there isn't a ground available from the plug? (more)

I live in a very old apartment, with very old wiring. Many of my electrical plugs are three-prong, but a visit from a electrician confirms that none of the plugs are actually grounded.

Is there anything I can purchase (APC unit, etc.), or anything I can do to properly ground things? I obviously cannot get my landlord to replace the wiring, as that would entail replacing the entire electrical structure of the apartment (35 units).

posted by theNonsuch to technology (10 comments total)

Run the ground to a copper water pipe? I am not an electrician, though.
posted by carter at 8:21 PM on January 5, 2004

carter's suggestion sounds reasonable to me. Or - run the ground wire out the window and down to a metal stake pounded into the earth.
posted by troutfishing at 10:17 PM on January 5, 2004

You can buy adapters that accept three prongs on one side, and which on the other side have two prongs and a wire meant to be attached to the screw holding the outlet cover to the workbox. That assumes the box is properly grounded. It's probably not, in your case. That wire on the adapter is going to have to connect to something that goes all the way outside and into the earth somewhere. Some people find the nearest cold-water pipe (must be copper all the way to the main) and connect it to that. Here's some info on the dangers of using ungrounded appliances. Here's one solution that uses GFCI outlets to protect ungrounded circuits.

I am not an electrician. These are just starters for your own investigation. If you don't feel comfortable acting on your own research, consult with an electrician (about $40/hr.) about your problem.
posted by stupidsexyFlanders at 10:25 PM on January 5, 2004

GFCI outlets will protect the user against shock but don't protect equipment plugged into them, as explained here. You still need a true ground.
posted by TimeFactor at 3:58 AM on January 6, 2004

What are the ground plug laws in your state? Better yet, what state are you from?

(You could legally make the landowners install grounding, or tip off the local station)
posted by Keyser Soze at 4:52 AM on January 6, 2004

wow. surely your wiring is illegal. can't you send an anonymous letter to the local govt offices (or electricity supply co?) and get the landlord forced to fix things?

[stating the obvious:] if your ground isn't grounded and anything plugged into it shorts to ground, everything that's "grounded" will become live. that's not a good thing. if you've connected ground to your water pipes and they aren't grounded either (say there's a plastic pipe near the mains) then in the same situation all your taps become live. unhealthy.

hopefully if something like that happened you'd have a circuit breaker trip or have enough leakage to take out a main fuse (before a fire starts). i don't know how common residual current breakers are in the states (from the sound of things, that's what is called a GFCI above) - they're probably not present in an old building with bad earthing...

if you have access to the suply for your appartment, and can cut the supply there, i'd fit a (suitably rated - do you have an electric cooker in your kitchen or electric water heaters?) circuit breaker there. doesn't solve your earth problem, but ups the chance that you'll stay alive :o)

(curiously, the conversation i had just before coming to this site was about someone who died after receiving a shock from a bad earth.)

i don't know how people verify ground connections. connecting to the water supply is common, but i don't know how to reliably test it. maybe you can get the electrician back? i have heard that driving a stake into the ground isn't 100% reliable - depends on the local conditions.
posted by andrew cooke at 5:01 AM on January 6, 2004

My APC power surge/battery pack thingy had a light that went on if there wasn't a proper ground (In my old place I connected to the plumbing) - I'd assume a hardware store or electrical supply place would have a cheap tester...

Also, depending on the age of your place, if the lines going to the outlet are sheathed in metal MTX housings (is that the right term?) you can install a 3-prong box (or use the existing 3-prong) and ground it to the MTX housing. I'd still want to test it somehow to make sure.
posted by jalexei at 6:09 AM on January 6, 2004

I live on the fourth of seven floors in a seventy unit building built (and apparently wired) circa 1930. Everything is two prong, and running a ground wire to the ground would be pretty difficult. What do I do?
posted by cortex at 7:45 AM on January 6, 2004

andrew cooke, there are normally "grandfathering" provisions in most states/provinces for buildings with out of date wiring. It sucks, but it's true. As long as they never touch the wiring it'll probably stay like that forever. :-(

Do you have cable TV, cortex? According to most bylaws, all cable TV cables have to be grounded properly. It's not a thick cover, so it probably wouldn't save your life, but connecting the ground pin to there might be better than nothing.

Failing that, a cold water pipe of any kind is also better than nothing.

If you want to check if it's connected to ground in _any_ way, meter from it to the "hot" side of the plug... You should see 120 volts.

Hope that helps and don't hurt yourself -- call an electrician first.
posted by shepd at 9:57 AM on January 6, 2004

Just be aware that (as mentioned above), connecting any sort of electrical circuit to the plumbing can make it live if there is leakage to earth or if anything shorts out. In particular, be aware that this may make the plumbing in the whole building live, leaving you open to lawsuit oblivion if something goes wrong. A few years ago, an acquaintance of mine was killed by an electric shock caused by having an electrical earth attached to plumbing because, unknown to him, an electrical appliance had a short that went to earth and he touched the water pipe going down the outside of the house at the wrong time.

If you just want to drain off static from the computer, you could connect a wire from the case to a water pipe, which still leaves the possibility that you could electrify the whole building if your computer case became live, but this is pretty remote and probably safe enough.

Sometimes, it is best to leave well enough alone ...
posted by dg at 2:44 PM on January 6, 2004