How old is your house? Does it have 2-prong or 3-prong outlets? It may not be a grounded system, in which case the box may not be bonded to a ground, so attaching the ground wire to the box won't do anything for you.

Hi! House was built in 1953. Has 3-prong outlets.

They have the fancy test/reset options, if that makes a difference....

Somebody just suggested getting an ohms reader and if resistance on the neutral wire is high, the box isn't grounded and screwing a grounding wire to it won't make a difference anyways.

If this is original 1953 wiring to the house, most likely it isn't grounded. Even if it is, the grounding is likely to be through the shield of old BX cable, an unsatisfactory and possibly unsafe ground.

Bravo for someone PROPERLY installing GFIs to replace the 2-pin receptacles in an old house with ungrounded wiring. If they also marked them "No Equipment Ground," triple bravo.

You can indeed use an ohmmeter (get a cheap digital multimeter from the cheap tools place) to test for a ground at your ceiling box. This must be done with the power off. I strongly recommend opening the main, not just a branch breaker.

Measure resistance between the white wire and the metal box. If it's on the order of a few ohms (less than 10), the box is grounded. If it's high (over 1000 ohms), it's not.

There's also a way to test for ground with the power on. Ask if you're interested.

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If your wiring is not grounded, you have a couple of choices.

One is to have the circuit rewired.

The other is to coil up the bare ground wire from the fixture, insulate it with electrical tape, and just leave it there in the box (the way the old one was done, but a little better). I guess that would be theoretically a code violation, since you're not following the fixture's installation instructions. (Ron?)

If your wiring IS grounded, or if you want to play dumb and follow the fixture instructions as if it is, again you have a couple of choices.

You can use a grounding clip. Get a wire nut and a 6" long piece of green #12 solid wire from the same place you get the clip.

Strip about 3/4 inch of the plastic insulation from each end of the green wire. You can use a knife if you're careful.

Hammer the clip onto the edge of the box with one bare end of the green wire under it.

Using the wire nut, connect the bare wire from the fixture to the other bare end of the green wire.

Instead of using the grounding clip, you can drill and tap the box for a 10-32 grounding screw. Fasten one end of the green wire under the screw, and wire nut the other end to the fixture bare wire, as above.

Or if this all sounds like too much hassle, you can call in an electrician. :)

(Links are meant as illustrations, not endorsements.)

I'll bet you dinner that the box is not grounded and, if that's the case, there's no point in attaching a ground wire to it. The only way to ground the fixture is by running a ground wire to the box and having the other end of the cable connected to some other wiring in the house that is properly grounded or all the way back to the panel of fuse box (which should also be properly grounded). I also bet that those 3-prong receptacles are replacement for old 2-prong models, and, if you inspected a couple of them, you would probably find that there are no ground wires running to them, either. You might want to pull off the breaker (or fuse) box cover and visually inspect your wiring to see if there is grounding in any of the house circuits at all. If you do this, throw the main breaker first and avoid touching anything inside since you could electrocute yourself by poking around if you don't know what you are doing.

Thank you both for taking the time to write such thorough information! I think I am going to call in the professional (my mother has now yelled at me for taking this on!) - but this information has been very educational.

Elizabeth, get one of those cheap testers which look like a grounded plug with 3 lights on it. Plug it into each (or at least some) of your grounded receptacles. The pattern of the lights will tell you whether the receptacle is grounded. If most or none of them are, then kudzu9 is right. Also, your light fixture may have been wired with metallic cable (e.g. BX) which can act as a ground, if properly attached to the box at the other end, I can't tell from your picture if it is.

"The pattern of the lights will tell you whether the receptacle is grounded. If most or none of them are, then kudzu9 is right."

They're almost certainly not grounded.

Read the posts above again. She said they were GFIs: "They have the fancy test/reset options, if that makes a difference.."

"Also, your light fixture may have been wired with metallic cable (e.g.
BX) which can act as a ground, if properly attached to the box at the
other end,"

Don't bet on it! It's unsafe to rely on (or even use) the ground provided by old AC (such as BX).

The AC jacket is a long, coiled strip of metal spiral wound and loosely crimped. As the cable ages and the metal oxidizes, the coils stop making good contact with each other at the crimps. You effectively have a long coiled-up strip of light metal -- a heating element!

Old AC has started fires when a ground fault through that relatively high resistance drew too little current to open the OCP, but instead heated the shield red hot.

That's why a bare bonding wire or strip was added to later AC. But I don't think it was added until some time in the 1960s or even 1970s. Maybe someone else remembers when it was added.

I'm not a pro, so I don't have wide experience with AC; but so far, I've never found an old AC installation that had the bonding wire. :-(

So you shouldn't ever use old AC as a ground. It's safer to have no ground at all than to use that jacket as a ground.

In the OP's case, since someone (properly!) installed GFIs, most likely there's no ground at all. My wild guess would be that the house is wired with old 14-2 and 12-2 NM, with no ground wire.

I hope everyone knows what AC and OCP are (I don't).

AC = Armoured Cable (or maybe it's "Armour Clad")

OCP = Over Current Protection? Basically a circuit breaker or fuse

Sorry, that was pretty careless of me. Too much jargon.

Right, AC = armored cable

OCP = overcurrent protection, such as a breaker or fuse

Thanks!

DavidR, my 120 YO house has AC for its initial wiring (I don't know if it's from 120 years ago, but there is no K&T wiring at all). There are a few of those AC cables left, most around the basement ceiling but some embedded in the walls. These don't have ground wires in them and I have been using the armor as the ground. Should I disconnect those grounds? Some are for ceiling lights. I've replaced all the cables I could with more modern wiring, but some I can't replace.

mtvhike,

If it doesn't have the little bonding strip then you shouldn't use it as a ground. Note that the bonding strip is different than a ground wire, so you may not have noticed whether it was there or not. Take a closer look to see if it's present.

Snap a picture and post it if you aren't sure.

AC goes way back -- to 1901. It took a while to catch on, but became pretty widely used in the 1930s. I've run into a couple of old houses (1920s / 1930s vintage) that still had a lot of the original knob and tube, and just a little bit of AC, notably for an electric range.

So AC would have made the scene a little too late to have been used in wiring 120 years ago. But it's possible that your house was first wired some years after being built, or that much of the wiring was installed later.

As for what to do with it today, for sure, if neither a bonding strip nor a bonding wire is present in your AC, you shouldn't use its armor as the grounding conductor. It's definitely not safe. Some folks even say that you should only use the armor as the EGC if it has a bonding wire, and that you shouldn't count on the bonding strip, because it's too fragile.

The real issue here, for me, is that some of this AC is inaccessible, so I can't easily replace. All which is in my basement can easily be replaced, but those runs which originate in the oldest fusebox (which is now simply a big junction box) run inside an outside wall to a couple of ceiling lights (and, perhaps, a receptacle or two). As DavidR implied, the wiring was probably not original - there was a major remodel done in the early 20th century which included adding an indoor bathroom (prior to that, there was only an outhouse!); probably done then.

If it can't be replaced, then you have to remove the 'fake' grounds. It's safer that way.

With lights, I don't think grounding is a big deal (but maybe others can chime in if I'm wrong). If you're worried about it, you could change the breaker to GFCI.

With receptacles, you can't have 3-prong regular receptacles on an ungrounded circuit. You'd either need to replace the receptacles with two prong ones or install GFCI. I think you'd need to add the "no equipment ground" stickers to those receptacles.

GFCI makes it safe for humans, but most (all?) surge protectors require an actual ground, so any electronics may not be protected if they are plugged into those receptacles.

"you could change the breaker to GFCI."

Excellent idea!

"I think you'd need to add the "no
equipment ground" stickers to those receptacles."

Correct, but I almost never see it done.. It's a shame that the GFI makers don't bundle "No Equipment Ground" stickers with them.

I make them with a Brother label maker. They stand up pretty well.

"most (all?) surge protectors
require an actual ground, so any electronics may not be protected if
they are plugged into those receptacles."

They have MOVs across the line, and from each side of the line to ground. (The rest of the circuitry in there is to monitor the condition of the MOVs.) You get some protection from the one across the line, but not nearly as much as if you had a proper ground.

IIRC, many code editions ago, it used to be acceptable to ground outlets to a nearby metallic water pipe. That's no longer allowed in permanent wiring, but maybe you could plug your surge suppressors into 3:2 pin adapters and then connected the adapter's ground terminal to a water pipe ground with #14 or #12 stranded wire.

I'll have to check when I go home, but I think perhaps the only receptacle on this line is a GFCI one in the kitchen, behind the kitchen sink!

I really bet no one can see what’s going on here, but I am trying to replace my old
light fixture and I understand the white and black (need to put new fixture white with white and black with black), but I cannot for the life of me figure out the ground wire. It’s on the new fixture but cannot determine where it is in the junction box. I’m at a loss.

You may not have grounding in that box...or perhaps the whole house But it is hard to see with all that electrical tape that shouldn't be on there. How old is the house?

Built in 1945 haha

My last house, built in 1952, was all 2-wire cable with no ground wires...legal at that time. Unless there is metallic conduit running to that box as a source of grounding, you likely have none, in which case, there is no point in connecting the fixture's ground wire to the box.

So it’s okay to just connect white to white and black to black? What do I do about the copper wire on the new fixture then?

1) It's ok to connect white to white and black to black if you have a single black and a single white that was connected to the old fixture. But you can't just connect all the whites and all the blacks inside a box together because there could be more than one wiring circuit in there. 2) As for the ground wire on the fixture, it's basically useless because there is nothing to connect it to. The fixture will work fine without that wire being connected to anything. Just curl it up and make sure it can't contact any live wires in the box.

At some point you need to have an electrician look at your wiring. It looks, for example, like there are too many wires in that box to comply with code limitations on "box fill," and it's not clear if the existing wires are properly wire nutted because of that mess of electrical tape. What you have there looks like the work of an amateur who may have improperly added another circuit to the box, possibly used under-sized wire nuts, and then taped everything up because live wire ends were not fully enclosed by the wire nuts.

Okay thank you so much! Will proceed with caution! The old homeowners def did a bunch of shoty work.