Power and ground in old houses

I routinly get asked to work on computers in buildings that have pre-war wiring. Two prong receptacles, not many of them, and who-knows-what behind the walls. Of course everything the user wants to hook up requires 3 prong outlets.

When I take the wallplate off I find rubber and fabric-insulated wire that can crumble if I disturb it. There is no way I'm going to try to put a modern grounded receptacle here.

I can scrape the paint off the plate and put a 3-wire adapter with a ground tab in with an OK connection to the ground tab. A wiring test gadget shows that hot/neutral/ground is correct. (or not, in one case.)

What's acceptable practice here ?

I'm not going to do any electrical work. I'm asking if anything short of getting a new run from the panel is acceptable practice.

It depends on local code. AFAIK, the NEC allows two wire service to be converted to 3 prong plugs by replacing the recepticle with a GFI recepticle.

Those cover-plate screw ground adapters are only suitable where armored cable has been run, grounded at the panel and bonded to the outlet metal box. The cover screw is then part of a tortuous ground path.

In any case, a knowledgeable electrician should be involved.

-- Robert

Back when I worked for a telecommunications company, we told the client what power was required. It was their responsibility to provide it. Advise the client what you've found and have them call in an electrician. Any attempts to bastardize the power cables can bring you a lot of grief, should problems develop. The only legal way to use a grounded plug on two wire circuits, is to use a GFI. Then again, unless you're a licenced electrician, you've got no business touching a clients AC wiring.

That's not your concern. It's the customer's responsibility to provide a safe power source. Make sure you use an outlet tester, should a "grounded" receptacle suddenly appear. It's always a good idea, to carry one of those testers in your tool kit.

The customer is asking _me_ for advice.

Al,

Everyone here seems to be singing pretty much the same tune. You don't want to get involved in the outlet or any other part of the electrical situation. Your responsibility ends at the end of the power cord to your equipment. If the proper receptacle is not present, tell the customer what is required and walk away. That way it is not your responsibility if any and we mean _ANY_ problems arise that can be traced back to the circuit or outlet where your equipment was connected to the power lines.

Rodgers Platt

My advice would be -- it is likely possible to do something without replacing the run, but that local codes vary and he need to consult a licenced electrician. Of course you don't know any, because cabler hate electricians, and vice versa :)

You don't want to give him _any_ inkling of solutions like GFI or grounded-box screw taps because should something go wrong, you most certainly will be liable "He told me X would work". _You_ are seen as the expert, and consequently have additional responsibilities.

-- Robert

And the only answer, is "fix it".

Al Dykes posted for all of us...

The only way to test a ground is with an Ideal Industries "Sure Test". The 3 light testers are a wishing and a hoping.

Are you certified in your AHJ for high voltage?

Wiremold/Panduit makes surface mount raceway with this situation in mind. Has a divider between the low & high voltage. Get with an electrician and confab what to install. He/she will be familiar with the area & requirements. Look out for an "electrician" who does low voltage also; he will not be your friend. Provide a package solution to the customer by one of you possibly subbing to the other.

In which case the best advice you can give the customer is "Get an electrician in. Your computer/network/PBX/whatever is not going to work well and could be dangerous without a proper electricity supply."

By the sound of things the existing stuff is not fit for connecting