[sci.electronics] Need help grounding an old electrical outlet

rubin@function.mps.ohio-state.edu (Karl Rubin) (08/09/90)

I have just moved into the third floor of an old house with very old
wiring, and I would like to be able to plug in my computer.  None of
the outlets are grounded, and none of the outlet boxes are grounded.
   Question:  How can I ground an outlet so that it is safe both for 
   me and my computer?
I will only be renting this place for a year, so I am not interested in
major rewiring.  It has been suggested that I could connect the ground
wire to the neutral wire in the outlet.  Will this be safe?  Does anyone
have any other suggestions?  Thanks for your help.

dbell@cup.portal.com (David J Bell) (08/09/90)

>I have just moved into the third floor of an old house with very old
>wiring, and I would like to be able to plug in my computer.  None of
>the outlets are grounded, and none of the outlet boxes are grounded.
>   Question:  How can I ground an outlet so that it is safe both for 
>   me and my computer?
>I will only be renting this place for a year, so I am not interested in
>major rewiring.  It has been suggested that I could connect the ground
>wire to the neutral wire in the outlet.  Will this be safe?  Does anyone
>have any other suggestions?  Thanks for your help.

ARRRGGHH!!   DON'T just use the Neutral as a ground - one reason for
providing a safety ground is in case of loss of the Neutral. The easiest
thing that comes to mind is to go to the local hardware store and get
one of those grounding adapters for each outlet you need. For the
computer system, I'd suggest a power/surge supressor strip for all
the power cords, and one adapter plug for the strip to plug into.
Check to determine if the steel box of the outlet is grounded; most
are, even in non-grounding outlet (old) systems. If so, the metal tab
on the plug side of the adapter goes under the cover screw and completes
the ground. If not, you'll have to run a wire, at least 14 ga., to
the nearest cold water pipe and clamp it on with either an electrical
grounding clamp made for the purpose or an automotive hose clamp.

Dave       dbell@cup.portal.com

adams@swbatl.sbc.com (Tom Adams - 235-7459) (08/09/90)

>ARRRGGHH!!   DON'T just use the Neutral as a ground - one reason for

>the ground. If not, you'll have to run a wire, at least 14 ga., to
>the nearest cold water pipe and clamp it on with either an electrical
>grounding clamp made for the purpose or an automotive hose clamp.

You should also be aware that new copper plumbing in old houses is often 
electrically isolated from the older galvanized iron plumbing.  This is done
to prevent corrosion problems between the different metals.

For a years rental you're probally just as well going with grounding adapters
unless the outlet is particularly hazardous (e.g. a washing machine outlet
in a damp basement).

-- 
uunet!swbatl!adams or adams@swbatl.sbc.com     
Tom Adams: 314-235-7459: Southwestern Bell Telephone Advanced Technology Lab
BOOKS WANTED: pre-1930 radio, electrical & scientific topics

dya@unccvax.uncc.edu (York David Anthony @ WRPL Wadesboro, NC) (08/10/90)

In article <1990Aug8.213846.20482@zaphod.mps.ohio-state.edu>, rubin@function.mps.ohio-state.edu (Karl Rubin) writes:
> Can I connect the ground wire to the neutral wire?


	No, no, no, no, no, no, no, no, no, no. NEUTRAL IS NOT
GROUND. 

	The whole point of a safety ground are 1) to place the
chassis of the equipment at the bonding potential of local
earth (e.g. water pipe) 2) to prevent RFI/EMI from being a hassle
(sometimes a problem where mutiple feeds have large inductive
loads on some of them) and 3) TO SAFELY CONDUCT A FAULT CURRENT
FROM THE MAINS TO THE CHASSIS OF THE EQUIPMENT LONG ENOUGH
SO THAT PROTECTION DEVICES CAN OPEN THE CIRCUIT.

	The proper way to do this is to have a licensed electrician
rewire the outlet PROPERLY for Class I use. Period.

	I almost lost my wife this way because some asshole
installed 3-wire outlets and depended on the metallic armour
in my aincent house to conduct the fault current.  The frame
of the refrigerator rose to line potential when the defrost
heater shorted to its frame.  Can you say "let go potential"
Sure. I knew you could.
	
	Even if the neutral were to short to the equipment 
chassis, there is almost always a potential between neutral
and ground because of the resistance in the neutral circuit.

	Screw the computer. It's your life we're talking about,
man.

York David Anthony
WRPL (FM) Wadesboro, NC