rewiring to fix open ground?

Seams there are devices made just for this purpose, the one I see most in googling this is called a (Hum X) it’s a filter designed to eliminate ground loop. And what you may want to buy if my above suggested test does prove to show you indeed have a ground loop condition. The links below are some interesting reads on the subject, and point out a potential danger in playing your instrument without a ground long term. The last one has an interesting concept of using a ground fault outlet, wired as if being used in a circuit without a ground wire. Others may comment on that solution and the safety of that. Could a guy make a short extension cord with a two prong plug on one end and a GFCI outlet on the other in a box and get an acceptable level of safety while eliminating the ground loop? That I don’t know. I know they make short adapters with GFCI built in them that have three prong plugs and carry the ground thru.

https://www.youtube.com/watch?v=qBEvnSmXc84

http://www.harmonycentral.com/t5/Guitars-and-Amps/Banish-Ground-Loop-Hum/ba-p/34633804

http://www.epanorama.net/documents/groundloop/problem_solving.html

i've thought of getting something like that but the humx and other similar devices only get rid of the hum but still risk shock and the gfci outlets only fix the risk of shock. i'd like to get rid of both.

quoted from HERE

OPEN GROUND receptacles indicate that the bare copper wire in the sheathed cable is not connected to the green
screw on the receptacle. It also occurs frequently in older homes originally wired with a 2-wire system (knob and
tube or duplex wiring) where an upgrades has included a 3-prong receptacle. This is an unsafe practice and does
not comply with current Electrical Codes – which requires that original and replacement outlet be grounded correctly.

In some installations, the ground (bare copper) wire may have been connected to the metal receptacle box in which
case some homeowners use an adapter connected to the cover screw of the outlet to achieve ground. This is an
unreliable method and is against most Electrical Codes.

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my ground is only hooked to the metal box behind this outlet, could my problem be as simple as unhooking it from the metal outlet box and attatching it to a green screw on the outlet or am i missing something

also what is the trick to getting the outlet out to work on it? either the wire is too short or it wont pull through the back of the box. while trying to get it out far enough to show the wires behind it i've tried everything short of putting both feet on the wall and pulling on the outlet with both hands like a cartoon. i did get it out far enough that i could see the ground is connected to the top and bottom of the metal outlet box and that white wires are connected to both silver screws on the outlet and black wires connected to both brass colored screws. and there is a green screw like the quote above mentions with nothing attatched to it

Sometimes older wiring or some electricians seemed to really scrimp on the wire length. Some of the older boxes were not as deep and the kept the wires short making them harder to work on. You have two blacks and two whites that means one black and white are feeding the box from someplace (could be another outlet) and the other pair is going off to feed something else. The bare wires are the ground the white is the common and the black is hot. The ground wires should be joined together in a way that connects them both to the box and also that green screw on the outlet. That green screw goes internally to the bigger round ground prong hole in the outlet.

Sounds like the outlet isn’t grounded at this point but you have wires in there to try grounding it with. If that’s the case you are using it now without a ground and the noise isn’t a ground loop of any kind I described.

After turning off the power and if you are going to take it apart to get in there and work figure out what black wire is the power to the box and mark it for future reference. You might have to take the wires off powered down and then carefully have them apart turn the power on and check with your meter for the hot black wire. Then shut the power back off. There should be a clamp in the back holding the wires and you may be able to get a little more length if you loosen that clamp. The ground wire and the common should be the same potential with the hot black wire when testing. Get a piece of green or bare wire and fix the grounds up like they are supposed to be and give it a try again.

bud16415 said:

Sometimes older wiring or some electricians seemed to really scrimp on the wire length. Some of the older boxes were not as deep and the kept the wires short making them harder to work on. You have two blacks and two whites that means one black and white are feeding the box from someplace (could be another outlet) and the other pair is going off to feed something else. The bare wires are the ground the white is the common and the black is hot. The ground wires should be joined together in a way that connects them both to the box and also that green screw on the outlet. That green screw goes internally to the bigger round ground prong hole in the outlet.

Sounds like the outlet isn’t grounded at this point but you have wires in there to try grounding it with. If that’s the case you are using it now without a ground and the noise isn’t a ground loop of any kind I described.

After turning off the power and if you are going to take it apart to get in there and work figure out what black wire is the power to the box and mark it for future reference. You might have to take the wires off powered down and then carefully have them apart turn the power on and check with your meter for the hot black wire. Then shut the power back off. There should be a clamp in the back holding the wires and you may be able to get a little more length if you loosen that clamp. The ground wire and the common should be the same potential with the hot black wire when testing. Get a piece of green or bare wire and fix the grounds up like they are supposed to be and give it a try again.

Click to expand...

ok i went for another look and yes i have 2 seperate sets of wires. not sure what it would be feeding, this is the only outlet in the room.

the grounds are not touching each other, one is connected to the clamp at the top and one to the clamp at the bottom of the metal box.

couple of questions

1. do i need to use any special gauge or type of wire? im pretty sure i have some 12-2 laying around if that will work.

2 can i leave the insulation on it?

3. do i need to connect the wire i add to both ground wires or just fasten it in with one since both are connected to the box?

is the forum unavailable for anyone else? i kept getting error messages for the past few minutes

Yes, the site was down for a bit of time this morning. All is better now!

By code the wire is to be bare or green for ground. Just twist them all together good and or connect them with a wire nut and run one to the green screw on the outlet. I’m not 100% sure how your local code calls for it to be done. But they all need to be together and one to the outlet and one to the box if it is a steel box. Plastic gets no ground wire.

found a section of the same type of bare copper used for the grounds behind the outlet while waiting for a reply, now i just need to find some monster sized wire nuts and try to figure out how to shut the power off only to that room, so i dont have the woman and kids bugging me asking when ill turn the power back on every 5 minutes.

Ya you really want the power off before you even try and pull the receptacle out especially with a metal box. Plug a lamp in it and have one of the kids yell (if old enough) when the light goes out. Then go to other rooms and see what’s also off and you will have a clue to what’s feeding what.

Plug a lamp in it and have one of the kids yell (if old enough) when the light goes out

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Plug in a radio and turn it up real loud. You will know when the circuit goes off. with out help.

i wish it was that easy lol would have to be one hell of a loud stereo. i cant even hear my GF yelling for me when she's upstairs and im in the basement. need a middle man to relay the message.

or i could just crank the amp gain and volume up and lay the guitar across the top of it. pretty sure the neighbors 3 houses down would know when that thing quit squeeling.

Run an extention cord for some distance down the stairs so could hear a radio playing while flipping breakers.

Do they still make radios that plug in? I know they do, we used to use walkie talkies for such things but now with everyone packing a cell that’s the method of choice over screaming. How many times have you called someone you were with in Walmart to figure out where they are at.

There are devices on the market that you plug in an outlet and it sends a tone on the wire, you go to the basement with the other half of the device and touch the breakers to find the correct one. Another method I have seen is to get a heavy duty Xmas 120v flasher box and plug a 100 watt bulb into it go to the panel and use a clamp on amp meter to find the wire that’s pulsing like the light. I have seen electricians build a homemade load box with a switch to trip a breaker, never looked safe to me and if you see one described to build DIY I would not recommend doing that. I never trust any method and once I figure out what breaker it is I still check the wires before going to work on them. If there is even a remote possibility that someone is going to turn that breaker back on you need to post a sign or something warning (Life on the Line) or something meaningful. In an industrial setting we use a system of” lock out tag out”. But that’s not practical for home DIY.

What I would recommend is taking the time once to go thru your house and map every outlet and light and then figure out what breaker powers each. For some reason there is a place to record that inside the panel but they are labeled so poorly it’s hard to figure out at least in the homes I have owned. Do it once and be done with the job and in an emergency you won’t have to mess around. It’s also good to know that outlets on the same circuit are broken up between different rooms etc.

thanks for all the help folks. i shut the power off and hooked the ground to the outlet and it seems to have done the trick. now im wondering how many other outlets are like this.

the whole house rewire we were planning may not be half as bad as we expected, if the rest of the 3 prong outlets have modern wire behind them also and just need grounded that would be great, i was expecting knob and tube. there is knob and tube wire hanging all over in the basement and attic running here and there but im wondering if they just never pulled it when they installed the new pannel and ran the newer wiring to most of the rooms.

Glad it worked out. My house they left all the knob and tube also. Take your time test it and rip it out. What worries me in your case is why anyone would wire grounds like that. And it would still be a good idea to pay a pro to look it over to see if they didn't do something else crazy. Don't be a stranger to the forum. And good luck with the music.

bud16415 said:

Glad it worked out.
My house they left all the knob and tube also. Take your time test it and rip it out. What worries me in your case is why anyone would wire grounds like that. And it would still be a good idea to pay a pro to look it over to see if they didn't do something else crazy. Don't be a stranger to the forum. And good luck with the music.

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im still going to post pictures and stil going to have a pro come and finish converting everything to more modern wiring and make sure my family isnt going to burn to death


stranger? nah lol not as long as this place is half as helpfull with the rest of the home repair catagories. this is our first house and i want to learn to fix it up.

Seems like insurance companies get nervous when houses have K&T.

Also, your house may be lacking wall insulation to avoid overheating the old wiring. This can checked by looking at your heating bills.

You could check if the remaining old wire is even carrying power. If it does, finding the source and routing for the neutral and hot conductors can be challenging.

Wuzzat? said:

Seems like insurance companies get nervous when houses have K&T.

Also, your house may be lacking wall insulation to avoid overheating the old wiring. This can checked by looking at your heating bills.

You could check if the remaining old wire is even carrying power. If it does, finding the source and routing for the neutral and hot conductors can be challenging.

Click to expand...

heating bill was insane, so we put in a wood burner last spring for this winter. while putting the wood burner it we confirmed that the walls arent insulated, just some sort of plaster crap with wooden slats coverng the studs then brick.

some of the knob and tube is definatly still carrying power, all the outlets in areas like hallways and in a couple of rooms still have knob and tube behind them, attic lights and outlets are all knob and tube and who knows what else. im only going to mess with it on an as needed basis untill i can afford to have someone come and replace it all in the next year or two.