Underground Cable Locator

Status
Not open for further replies.
H

hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
mkgrady said:
Does ANYBODY think the Amprobe AT 2005 will find this cable? It being LV lighting and only a few inches deep.
Click to expand...

after reading the specs it should, dry ground is best in locating, but just remember when locating under ground wires use the method I described above, don't connect both leads to the cable, one to the cable and one to an electrode. I don't have one of these units but it sounds like a good one, so I cant really say how good it is. the important thing is learn how to use it, or you will be banging your head against a way trying to fly by the seat of your pants, been there and done that lol;)
 
D

dbuckley

Senior Member
Location
Canterbury, New Zealand
Well, the instruction manual says it should (p15 finding ground faults), and the theory looks sound enough. Wayne's advice you quoted seems to back up the manual. The thing is on its way to you know, so give it a go.
 
2

220/221

Senior Member
Location
AZ
mkgrady said:
Does ANYBODY think the Amprobe AT 2005 will find this cable? It being LV lighting and only a few inches deep.
Click to expand...

For a thousand dollars, It better!

I use a Progressive Electronics unit that cost abour $300. When it works, it works well. When it doesn't, it's a total waste of time. Sometimes it sends a nice clear signal thru the wiring, sometimes not. I have not been able to figure out why it does this but I do know that it doesn't like it when there is lots of activity underground, The signal wants to jump into other wiring and it picks up a crapload of static.
 
kwired

kwired

Electron manager
Location
NE Nebraska
220/221 said:
For a thousand dollars, It better!

I use a Progressive Electronics unit that cost abour $300. When it works, it works well. When it doesn't, it's a total waste of time. Sometimes it sends a nice clear signal thru the wiring, sometimes not. I have not been able to figure out why it does this but I do know that it doesn't like it when there is lots of activity underground, The signal wants to jump into other wiring and it picks up a crapload of static.
Click to expand...

Isolation of the conductor you are locating is necessary when there are others nearby, disconnect both ends of it so you do not feed through connected loads and back on other conductors.


I have a Rycom (not sure of model number) buried fault locator. I have never ran into a fault I was not able to find. Sometimes had a good challenge but always learn from the experience and next time situation is similar usually figure it out faster.

I bought this unit used from a utility company for $500, New ones are worth at least $2500 or more. It is a very basic unit to use, does not have any digital readout or other fancy stuff. I have seen people use the fancy ones and not accurately locate what they are looking for - but that is usually operator error more than equipment error.

Number one rule if having trouble locating path of buried wire is eliminate unintended paths (isolate as I mentioned before). Locating a fault point can be challenging at times, soil conditions will effect how easy locating will be. With my locator there is a fault return probe which is used to locate the point of a fault. It tells you where current is leaving the conductor and returning through earth back to a ground probe located near the transmitting unit. I have had a few times where I could not locate where a fault was because soil was so dry there was literally no return current to locate. Placed water sprinkler over area for few hours and tried again and found fault almost immediately.

My advice is if you do not do a lot of underground work you may want to rent, subcontract, or whatever for the occasional times you may use something like this or it will take a long time to pay for itself. I do a lot of work on farms in my area and locate a lot of underground lines - even for other people that need something located for other excavation reasons.

And for finding faults - some locators only locate conductor path, you need a unit with a fault return probe to find most faults. Occasionally I have run into a clean break that I can find with the regular path locating probe because signal is lost at the break, but usually there is enough conductivity at the bad spot that you will still have signal on the other side of the bad spot.


I don't know the capabilities of the Greenlee circut tracer mentioned earlier in this thread but if it is like other circuit tracers I have seen you need a complete circuit to trace and you will need to pass current through only one conductor in the cable you are tracing and have a return path through another conductor routed away from your locating area otherwise the signal on the return conductor is in opposite direction of signal on traced conductor and signal is canceled.
 
480sparky

480sparky

Senior Member
Location
Iowegia
220/221 said:
For a thousand dollars, It better!

I use a Progressive Electronics unit that cost abour $300. When it works, it works well. When it doesn't, it's a total waste of time. Sometimes it sends a nice clear signal thru the wiring, sometimes not. I have not been able to figure out why it does this but I do know that it doesn't like it when there is lots of activity underground, The signal wants to jump into other wiring and it picks up a crapload of static.
Click to expand...

The better locators use a variety of frequencies to overcome congested site conditions. Rycoms all use 815 Hz, 8 kHz, and 82 kHz.
 
ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
220/221 said:
For a thousand dollars, It better!

I use a Progressive Electronics unit that cost abour $300. When it works, it works well. When it doesn't, it's a total waste of time. Sometimes it sends a nice clear signal thru the wiring, sometimes not. I have not been able to figure out why it does this but I do know that it doesn't like it when there is lots of activity underground, The signal wants to jump into other wiring and it picks up a crapload of static.
Click to expand...


I use one similar. The inductive clamp works ok, with a direct connection to an isolated conductor the best, but you are right occasionally the signal jumps one item to another and it is a real headache.
 
M

M_J_C

Member
Location
Southeast Florida
mkgrady said:
I need to locate a cable that has been cut and damaged. The cable is from a LV transformer used for landscape lighting. The cable is being used to send 12 volts to another LV lighting transformer and the 12 volt signal is used to turn on the remote transformer with a relay.

I can't be sure but I suspect the cable is only a few inches deep. And since it was presumably cut during recent excavation work around the property (in several locations) it may be just below the surface. Where the cable was cut it must have shorted the two conductors together as there is continuity between them but no voltage when the source is turned on. The total run length is about 200 feet.

Do I need to get a cable locator? If yes, what would be a good choice?
Click to expand...

If you have a TDR and have a good guess at the cabling path, you probably don't need a locator for this job. Just use the TDR to give you a wire length, measure out along the guesstimated path and start digging. A decent TDR can be found here: http://www.amazon.com/Triplett-Cable-Fault-Finder-Length/dp/B0002U3WY4 for less than $200
 
Last edited:
H

hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
M_J_C said:
If you have a TDR and have a good guess at the cabling path, you probably don't need a locator for this job. Just use the TDR to give you a wire length, measure out along the guesstimated path and start digging. A decent TDR can be found here: http://www.amazon.com/Triplett-Cable-Fault-Finder-Length/dp/B0002U3WY4 for less than $200
Click to expand...

And the same thing can be done with a good ohm meter, and the known resistance of the subject conductor per foot, this was the old way of knowing how much wire was still on a reel, and we also used it to find the distance to a fault once the Ω's per foot was known, but the problem with underground breaks is it doesn't work if the break in the wire is an open, or does it work if the wire has a high resistance short, or any resistance which will throw off the calculation and or the TDR.
 
M

mkgrady

Senior Member
Location
Massachusetts
M_J_C said:
If you have a TDR and have a good guess at the cabling path, you probably don't need a locator for this job. Just use the TDR to give you a wire length, measure out along the guesstimated path and start digging. A decent TDR can be found here: http://www.amazon.com/Triplett-Cable-Fault-Finder-Length/dp/B0002U3WY4 for less than $200
Click to expand...

Since the two conductors are shorted together and laying in dirt wouldn't that make the TDR difficult to use?

I received the AT 2005 yesterday. My threat to cancel the order caused the supplier to speed up the shipment. I plan to start testing next week.

Upon reading the instructions it was not clear to me which parts of the supplied equipment would be best to use. I will study the directions and review the techniques suggested in this thread before I begin.

Thanks for all the responses
 
S

shepelec

Senior Member
Location
Palmer, MA
220/221 said:
For a thousand dollars, It better!

I use a Progressive Electronics unit that cost abour $300. When it works, it works well. When it doesn't, it's a total waste of time. Sometimes it sends a nice clear signal thru the wiring, sometimes not. I have not been able to figure out why it does this but I do know that it doesn't like it when there is lots of activity underground, The signal wants to jump into other wiring and it picks up a crapload of static.
Click to expand...

I have the Pulser 2000H. It has always been dead on, even if the faulted cable has been 60" deep. The only trick is to be sure the contact points are moist, if you have a lot of rock you might have issues.

Remember fault loacation and cable tracers are different, some of the above posts are reffering to cable tracers. Fault locators use a high voltage pulse not RF energy as the whole wire will radiate.
 
Last edited:
mivey

mivey

Senior Member
mkgrady said:
Does ANYBODY think the Amprobe AT 2005 will find this cable? It being LV lighting and only a few inches deep.
Click to expand...
I know the Ideal 61-958 will because I have done it with deadly accuracy and it is similar to the Amprobe.

mkgrady said:
Upon reading the instructions it was not clear to me which parts of the supplied equipment would be best to use. I will study the directions and review the techniques suggested in this thread before I begin.

Thanks for all the responses
Click to expand...
Post if you have any trouble as it should be a straightforward thang. You will find the cut point where the signal falls off (be careful as the signal also changes at a turn). You can narrow down the cut point by reducing the receiver sensitivity as you move it closer and closer to the ground. You should be able to get within a few inches or better.
 
M

mkgrady

Senior Member
Location
Massachusetts
ptonsparky said:
Cable tracers make using a fault locater easier, but they are not required. With time and experience you can figure it out.
Click to expand...

Are you saying I could have just used a thumper? I have used them on MV cable but this cable is LV. In any case I don't have access to a thumper if that is what you meant.
 
A

Article 90.1

Senior Member
Another tip is to get some of the flags (like the ones used to mark out irrigation lines) and mark the line every few paces. This way you can take a few pictures and have it on hand for the next time you have to go back to this job site.
 
H

hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
Article 90.1 said:
Another tip is to get some of the flags (like the ones used to mark out irrigation lines) and mark the line every few paces. This way you can take a few pictures and have it on hand for the next time you have to go back to this job site.
Click to expand...

Or marking spray paint, just don't mark on sidewalks or anything the homeowner might not want painted:D
I use white for general purpose marking, but a have a couple cans of all the utility colors on hand to mark each one with there respective colors.
I do locates for private properties, where most of the utilities are privately owned, like camp grounds and mobile home parks, we have a few with primary metering at the street.
 
Status
Not open for further replies.
Top