How to ground an ungrounded electrical box

I have some outlet boxes that are fead with ungrounded wire due to the age of the house (when the house was built a ground wire was not required). Over the years new properly grounded circuits were added. Some of the newer boxes and the older boxes are along a crawl space. Can I run a ground wire from one box to another (yea sure I can- but is it a good idea?)? What would be the procedure to ground those boxes that I can get to but the wire feeding it or leaving it goes to where I can’t get to.

This depends dave. Are the new boxes already connected to the old boxes by metal conduit? If so, a simple grounding clip with a ground wire(use green insulated or bare wire for grounding) could be clip to the side of the box with a ground wire going to the outlet.

And what exactly do you mean by outlet? Do you mean the receptacles for plugging in appliances or a light fixture - these are both considered outlets.

Here’s a link to the National Electrical Code - hopefully you can find more info there if you don’t get what you’re looking for here.

the new boxes are not on the same circuit as the old. by boxes, I mean all electrical outlet, junction and light metal boxes. Also all wire used is Romex cable.

I will check you link tomorrow, too tired now.

I don’t know of any reason why you shouldn’t series-connect J-boxes to earth ground. Find the nearest earth grounded cold water pipe and clamp on to it. If you can’t locate any nearby point for earth ground that you can trust, skip merrily on down to the basement & clamp a #12 AWG to the conduit where the mains come in to the breaker/fuse box. Then take the other end of that to the nearest cold water pipe & clamp it there. If the house is as old as you say, all the pipes are metal (not PVC) and will provide a good earth ground network once you’ve done the grounding in the basement. I believe code allows earth ground wire to be uninsulated along its entire span.

When you’re all done, use this little gadget to verify the integrity of your hot, neutral & grounds.

(Don’t buy it from that site, for goodness sake. $27.60?? Radio Snack sells it for $3.99!)

I think another reasonable solution is to use a GFCI outlet – I don’t think they require a ground wire.

(This is based on a sort of fuzzy memory, so I’d check it out before going ahead.)

I’m still a little unclear on what the situation looks like, but here’s some general advice anyway:

If you have an ungrounded outlet & box, and you want to run a ground wire to it, then simply run a 12 gage, copper, un-insulated wire from the outlet/box to the neared valid earth ground point. The “valid earth ground” point may be another outlet/box which is grounded, a cold water pipe, metallic electrical conduit (which should be at earth ground), breaker panel, etc. I don’t believe there’s a problem with “daisy chaining” grounds, but you must be certain that each connection makes good electrical contact (clean, tight, and low resistance).

Finagle said, “I think another reasonable solution is to use a GFCI outlet – I don’t think they require a ground wire.” He is correct - in lieu of running a ground wire to an outlet, you can simply install a GFCI outlet. The same applies to outlets “downstream” from the GFCI, provided you apply a small label to each outlet that says “GFCI protected.”

There are two more things to consider if you go the GFCI route. There are a limited number of downstream outlets you can protect with a single GFCI (I don’t remember if it is 3 or 5), and on a practical basis you don’t want to protect an outlet on the second floor with a GFCI in the basement, if you have a “leaky” appliance plugged into the outlet you’ll be getting plenty of exercise running up and down the stairs. I also read on the board recently that someone lost a freezer full of food when the GFCI functioned properly and no-one noticed the power on that circuit was out.
There’s no problem with daisy chaining your ground wire, but use a pig tail at each box so you aren’t depending on the integrety of each connection to assure grounding downstream.

Thanks for the advise. I will go the daisy chain route. The GFCI route would prove too expensive and time consuming since I don’t know how many outlets are ‘down stream’ and can’t afford to replace all w/ GFCI’s.

Instaed of bare wire, I have 12 gauge stranded wirs in green insulation that I was thinking of using - I saw some clips that would allow attachment to the side of the box, or should I run it directly to the ground terminal on the receptical?

Also, there is one outlet that was upgraded to a grounded outlet, there is a 3 way wire (white, black, red, no ground) that only 2 wires are now used running to the next, can I use the 3rd wire to continue the ground to the next box? if so what color should I use?

You should connect both the box and the receptacle to the ground wire- that’s what I’d do in a commercial installation, if the boxes weren’t already grounded via conduit. If you were to only connect one, I’d do the receptacle.

If the the third wire in your cable isn’t used on either end, you could use that as a ground wire. Again, if it were me, I’d use red, leaving black and white for the normal hot and neutral colors. Put some green electrical tape on the red wire to indicate ground.


If you install the GFCI, you need to label it and any downstream three-prong outlets with “No equipment ground” in addition to the “GFCI protected” labels.

In my “Handyman” book, the answer to essentially this question is “Adding a ground wire to your existing outlets can be difficult and should be done by a licensed electrician.” Then they go on to recommend going the GFCI route. Maybe this is a clue…

As I recall, all grounds in your home wiring are required to originate at a single location (the breaker box), so the advice to attach onto the water pipes is a violation of the national electric code. Attaching to the ground wire of an outlet on a different circuit wouldn’t violate that aspect, but I am not an electrician, so I can’t say whether this is legal.

k2dave, I’d suggest reconsidering the GFCI approach. Electricity is something you don’t want to mess with. To find out how many outlets are downstream, you can disconnect the outlet you want to replace with a GFCI, make sure the wires aren’t touching anything, reset the breaker, and see how many outlets don’t work any more. Also, take note of how many amps the breaker is. There are 20 amp and 15 amp GFCIs (20 amps being more expensive, natch).

A couple more questions: Are your existing outlets polarized? If you aren’t going to have a ground, you at least better get the polarization correct.

Finally, why do you want/need to have three prong outlets, anyway? (I’m just wondering here. My personal confession: I once put in an ungrounded three-prong outlet so I could plug in a power strip for my stereo. None of the components had a ground plug, and I didn’t use it for anything else. But don’t you do this, of course.)

The polarization is correct. In hard to ground locations I might go the GFCI route but for that outlet only unless I know that there in only 1 or 2 boxes downstream. I am afraid that I might miss some critical outlets.

As for why I feel the need for grounding outlets, well my Pop always places great importance on that bare wire and taught me to respect it. I have seen friends not attach it and/or cut of the 3rd prong on ext. cords - that just makes me cringe.

Since I moved in to this old house I get a little nervious running my computer on an ungrounded outlet.

Thanks for the labeling tip

This may already be common knowledge to you, but I thought I’d throw it in just the same.
if you decide to replace the 2 conductor wire with 3, that would simplify running the wire through the wall, as you could just tape the end of the new wire to the end of the old wire, and as you pull out the old wire (from the other end), it’ll feed the new wire into place, as long as you keep the joint between the wires small enough to get through any holes in studs, and such…


The problem with running a the wire by pulling to other is that the old wire is tacked very well and very often. Also it doesn’t appear that the builders took the straight line approach to running them