Find junction box hidden in ceiling.

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Ravenvalor

Senior Member
Hello,

Is there an electronic tool that will help me locate a lighting junction box buried above a sheetrock ceiling? The customer wants me to make 1 - cut only and there is not an attic above this ceiling.
I have an underground cable locator, circuit breaker locator, and phone cable tone locator. I believe that the underground cable locator will work the best. However if there is a tool designed specifically for this task I would be interested in knowing about it. What about a plumber's camera? This will allow the holes to be much smaller.
Any suggestions would be appreciated.

Thanks,
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Hi Dennis,

Do you per chance know a name, manufacturer or model number?
I have a phone line tracer by ideal but it does not have much distance from the wire to the receiver range.

Thanks,


Ideal makes one that works for underground etc. but it is about $600.00

I have never used them so I don't know what brand to recommend. Search for tone generators. They come with a probe and the generator around $150-$200
 

hurk27

Senior Member
Use both a circuit tracer and a stud finder with metal locate on it, the circuit tracer will get you close and the stud finder in metal mode will zero in on the box if it is metal or has a metal cover, even a phone tracer will get you close enough to use the stud finder. I also have an under ground RDF unit that will put a Strong audio signal on the circuit so I can use the receiver part of my toner to get close to hidden wiring or box's, then I use the stud finder to follow the side of the rafter and if it doesn't have a cover it will blip as it crosses the box edge, and again when you get to the other edge, works great after you figure out which way the rafters run.
 

Ravenvalor

Senior Member
Thanks for all of the replies.

Dennis I have an Ideal $600 underground locator and will try it.

Hillbilly this box was purposefully recessed and buried above the ceiling but I will still use my level to check for bevels.

hurk27 I have an elcheapo studfinder but will run out and get a good one if it helps me find this splice.


I will report back to this thread tomorrow. Once again thank you for the help.
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
The phone tone gen or ideal will both work. The tone gen may be a better choice for the close distance. Is it an open you are looking for or just the junction? If you are lucky enough to have three or more wires flying to it that should help. Sometimes using just the ideal wand with no tone gets you close.
 

Ravenvalor

Senior Member
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The phone tone gen or ideal will both work. The tone gen may be a better choice for the close distance. Is it an open you are looking for or just the junction? If you are lucky enough to have three or more wires flying to it that should help. Sometimes using just the ideal wand with no tone gets you close.

Hello Folks,

I tried my $600.00 Ideal underground cable locator with the transmitter on its lowest setting, one transmitter lead connected to the black conductor of the switch leg and one transmitter lead connected to the white conductor of the switch leg, with the results being that the signal seemed to get blurred after traveling about 15' from the transmitter. I did not bring out my phone toner because I decided to take down another light fixture in the kitchen and cut a huge hole in the sheetrock above the fixture location. I stuck a flash light and a mirror in the hole and located a blue junction box with 3 - cables going to it. The box was not even pointing down towards the sheetrock, so I had to cut the mounting nails and rotate it 90 degrees.

I probably should experiment with the phone toner and the underground cable locator to improve my efficiency with them for behind sheetrock finds. I believe that there is a second junction splice buried in this ceiling so I need to be ready to find this one if it causes trouble.

I was ready to use the Dewalt inspetion camera if needed but fortunately I was able to return the $300.00 camera to Lowes without opening the package.

Thanks to all for the input. Have a great weekend.
 
one transmitter lead connected to the black conductor of the switch leg and one transmitter lead connected to the white conductor of the switch leg,

What's happening then is the radiated fields pretty much cancel, so a pickup won't get them as well. When tracing wires through walls & ceilings, I isolate all the wires in the cable then put the transmitter between an isolated lead and an actual ground. That radiates beautifully. Easier with LV and not having every white ending back at the same ground. (Never needed an underground locator, so don't know the usual practice there.)
 
I hope this isn't too corny but, there is a smart phone applicaton (free to download) that can detect electromagnetic pulses or any metal behind a wall and it progressively gets louder the closer you get, never had luck with anything more than 3 feet away but if it works for you could be a easy solution.
 
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
What's happening then is the radiated fields pretty much cancel, so a pickup won't get them as well. When tracing wires through walls & ceilings, I isolate all the wires in the cable then put the transmitter between an isolated lead and an actual ground. That radiates beautifully. Easier with LV and not having every white ending back at the same ground. (Never needed an underground locator, so don't know the usual practice there.)

We connect one lead to a short probe or screwdriver stuck into the earth for both the Ideal or the Tone Generator. Isolate the circuit from the neutral and EG bar if possible. Locate from several different ends of the circuit. Sticky notes will eventually converge at the suspect location.
 
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