tactic for finding "open ground" on circuit in a home?
 

Is there a tactic that make more sense than any other strategy to try to find an open ground on a circuit in a home? Is there a "usual" place where you would expect the problem to be?

I was doing some electrical for a new bathroom yesterday, and afterwards, noticed that the circuits that I used to get power for outlets are open ground. (makes the GFCIs useless). I'd like to get them fixed.

Other than running around the house with the little outlet wiring tester/checker, and getting into every box for a switch or light, is there a recommended/methodical way to find the problem?

I'm not counting on the wiring in this place to make sense (ie, room by room circuits or anything like that).

I'm hoping that it's at a light switch somewhere, but I have no evidence to support that.

I guess mapping every outlet with the tester/checker is going to be in my future.

GFCI's work just fine without a ground. You need to do some reading.

Finding the point of loss of continuity in the equipment ground circuit is not going to be easy. The way I go about it is to first try and map out which way the wires go from the panel. You do this by turning off all circuits and then switching them on one at a time, follow them as best you can with a touchless voltage tester. Then start at the closest device on any circuit and work your way down the line one at a time.

There are no guarantee's, just a bunch of work. You may have to pull each receptacle and each light fixture and check the individual wires. In an old house this is a wise thing to do anyway. Having 2 people working helps a lot with turning the breakers on and off as the work progresses.

If you accomplish anything, label your breakers and make a circuit map for future reference.

All you have to do is think like an electrician.
Today, lights and outlets are on separate circuits. Usually.
Tell the guy who wired one of my basement lights into the circuit for the outlets in the bedroom above. But usually, things one one circuit are close together physically. If there's not ground in the outlet box you're working on, go to the next closest outlet, heading toward the breaker panel. You shouldn't have to check every outlet in the house to find the problem.

Usual place for an error would be in the outlet box, someone didn't get the wire nut tight on the ground. Should be ground from the box, a pigtail to the outlet in the box, and then the wire going to the next outlet.

Or hey, there could be junction boxes hidden in the attic, buried in the walls, down in the crawl space. Those are always fun to sort out.

Just remember that Steve lives in a pre WWII house. There could be anything.

Note" GFCI's with no ground present must be labeled as such. Having a 3 prong recep with only a neutral and hot is illegal. Must use 2 prong outlet.

First make sure it is 3-wire and not 2-wire all the way through.
14 gauge is standard 15amp rated, and 12 gauge is 20 amp. The breaker should never be larger than the smallest thing on the circuit.

Flip that breaker. Find out everything which is on that leg in series. It may go through several rooms and through the basement or attic back to the fuse box. Use a pen and outlet tester (Greenlee is a good brand). There might be a junction or twist tie inside a wall, which is against code and not safe.

You may discover the lights/outlets nearest the fuse box might be grounded, which indicates that on the next thing down the line or at a junction box someone forgot to hook up the ground wire.

I think the electricians use the sonic tracing equipment which might be for rent.
Kill power, pull the breaker, attach that ground and find where it terminates. (I think that's how they work)
Test before touching anything.

I think you mean isolate the ground for any given circuit. Otherwise the tester is going to locate every wire on the EGC. And not tell you where the continuity terminates.

Thinking out of the box here:

In low voltage cat5 /cat 6 installs, we tone out the unknown lines.

If you confirm what is serviced by a particular breaker, then kill power to the breaker box. Unhook the ground, put a tone on it and follow till it stops.

Note - I don't play with high voltage, just a thought!

Yeah, that's what I was thinking. This is just a huge pain in the rear process of tracing stuff.

I rewired the downstairs bathroom. It had 4 lights and switches, 2 or 3 outlets (no GFCIs), and a fan. The fan was blowing air into the wall cavity. And the wiring for all of those old things were on multiple circuits and bouncing all over the place. Things are now much cleaner, there are only 3 lights, more outlets, and all of the outlets are protected by working GFCIs. Electrical isn't rocket science, but untangling someone else's previous work can be a pain.

Hmm, when I plug the tester into the GFCI outlet, I get
http://forums.pelicanparts.com/uploa...1639426816.jpg

And when I hit the button on the tester to reset the GFCI, nothing happens. The same tester in the downstairs bathroom will trip the GFCI on the properly wired outlets. If I hit the test button on the GFCI itself, it trips.

And I've got 2 different circuits upstairs (they may be fed by the same circuit somewhere) that show the same open ground, and both act the same when I use the test button on the tester.

The good news is that the house isn't that big and there aren't that many outlets, so "how hard could it be." (famous last words).

Thanks

This place is 100 years old. The good news is that in the early 90s, someone replaced all of the knob and tube with romex. The bad news is that circuits are not segregated or laid out how you'd expect.

Yes, there absolutely could be hidden boxes. Fortunately, there aren't as many hiding spots as a lot of houses.

I'll be fixing the problem eventually.

Still, that's on the right track.

Just repeating that you should know (I think you do) that a GFCI will protect all devices downstream from the load side. The grounds are tied together. The only exception to ganging grounds is when AFCI's are in use. Those breakers like dedicated EGC's. Still in any one given circuit, all grounds are tied to metal boxes, devices, and to each other.

"Bouncing all over the place" is the last thing I want to hear when it comes to electricity. ;):D

Sonic tracing equipment would be fantastic!

I do have a Fluke pen and a couple of outlet testers. Unfortunately, only one or two of the circuits are labelled at the breakers.

Hopefully, it's as simple as a box with a crap connection. We've got one or two switches that don't seem to do anything (very exciting). It's just going to be a hunt to track things down.

Every wire that I've seen is 12-2 (hot, cold, ground).

That would be cool. I've got a bunch of network cabling experience, but I don't have a tone generator.

Yes, in the downstairs bathroom, I have one GFCI protecting 3 outlets (itself and 2 on the load side), thanks.

I'm just glad to not be dealing with Al wiring like we had in our last house. All Cu is a luxury. No special outlets, no "NoAlOx", no occasionally tighting screws, no sparks coming out of outlets or switches, etc...

Well, this all got me inspired. I just changed out 4 ceiling fan lights for new LEDs, installed an LED rated dimmer switch, and moved one of the other switches in that box to another position to do a different light. All since my last post.

Nice

I'm still busy at work, and getting stuff done for the missus. No electrical work yet.

And on top of that, I discovered that I got home with the wrong quick connect fittings for the new compressor that I got. I need female threads for both ends of the hose that I bought, and ended up getting home with 4 male connectors that are all male threads. Fortunately, there's a shop up the road where I should be able to get what I need. Still, irritating.

any wire that isn't grounded will show up as hot, whether real hot or floating. here is your tool. https://www.lowes.com/pd/IDEAL-Single-Range-50-600-Volt-Non-Contact-Voltage-Sensor/5000240957?cm_mmc=shp-_-c-_-prd-_-elc-_-ggl-_-LIA_ELC_106_Tools-Wire-Connectors-_-5000240957-_-local-_-0-_-0&ds_rl=1286981&ds_a_cid=112741100&gclid=CjwKCAi A-9uNBhBTEiwAN3IlNL111SLPvJadHMgcYlHTbzLEl510vnUUUxe ixrrgiglVS6Nl2V5fNxoCtHYQAvD_BwE&gclsrc=aw.ds

Yep, I've got one of those. Thanks!

Earlier this month I changed out a couple lights for a new young tenant.
I was showing him how to use that tool to check for power, how to install, get a solid wire nut connection, etc.
It's a good thing I did...
Clicking the switch turned off the bulb...but the tester was still flashing at the light fixture....huh?
Apparently the panel rocker switch was slightly shorted internally just enough to let some current through.

(btw, I've got two FREE ugly purple art-deco wall sconces (upwards directional light) for any Pelican who wants them.)

I might want them. Pics?

I thought there were some better close-up pics but couldn't find em. They are at the rental.
Black/purple. I think the spatter is orange and yellow flecks. iirc
http://forums.pelicanparts.com/uploa...1639444419.jpg

Thanks tons, I'll check with the missus. She's wanting to add some Art Deco touches to our place. I'm not sure if there's any place that she'd want these, but I'll find out and let you know.

Got it. GFCIs protect an ungrounded circuit, but if you try to test them with a grounded tester, they don't trip which is supposed to be a positive result. On a grounded circuit, the tester works as expected.

I think the tester "test button" shorts hot to ground when pushed. If a ground isn't there it doesn't trip the GFI outlet.

An un-grounded GFI outlet still protects an overload surge from hot to neutral faster than the thermal spring breaker in the fusebox.

Ground is there to prevent a hidden short due to a hot wire touching the inside of a metal outlet/switch/the person flipping it.

Not doing any deep digging tonight, but checked the downstairs.

1 outlet shows hot/neutral reversed
1 outlet has romex with a ground going to it, but only has 2 prong plugs
1 switch didn't have a ground connected (fixed that, but still don't know what the switch does)
1 switch is a 3 way, but no idea what it does or where it goes.

The rest of the outlets show that they are wired correctly and the switches do something.

You didn't flip it, did you?

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Upstairs
room 1, 2 outlets, both open ground (both show a ground wire under green screw)
room 2, 2 outlets, one open ground, the other good (ground wire under green screw)
room 3, 2 outlets, one open ground, the other good (ground wire under green screw)
room 4, 1 outlet that I can see, wired correctly

that's what I was afraid of. Everything LOOKS like it's wired correctly. Anyplace that there are multiple grounds connected, the twist looks tight and extensive.

I guess this is going to be a pain in the rear search. Maybe there's a problem in a box in the ceiling at a light somewhere.

I believe you're correct. If the ground isn't connected to anything, then shorting it won't flip the GFCI.

ROFLMAO!

Oh no!

Any of you guys go a backhoe?

Protecting (i use the term lightly) people from an ungrounded circuit was achieved by a circuit utilizing polarized (now standard) plug sockets properly wired. It was common practice for two prong circuits to wire the neutral to the enclosure of an appliance. With no polarized plug way back in the day, it was possible depending upon how one plugged it in that hot got connected to the intended neutral. For the appliance it functioned fine. But if you happened to touch the appliance and say for example a metal sink with metal plumbing, you got a nice wake me up. Was very common to get the wake me up with old skool microwave ovens or old skool whole house audio/intercom systems.

Presuming a properly wired and functioning gfci circuit, the gfci breaker/socket senses that the current from the hot side is flowing and matched with the current on the neutral side. It pops when that is not the case. The intent is to prevent a situation where the current instead of flowing through neutral, flows instead by way of ground. If said current is under the limit of a traditional hot side breaker, said breaker never trips. In places where there is moisture/wetness involved, for example, the by way of ground can be through a person. Well if the hot side breaker never trips....

Which is clearly what people mean when they describe someone as "really well grounded." :D

one or two story dwelling?

two stories