My father has a underground wire to a panel in his garage from his house. One
lead of the 220V service has apparently "opened" somewhere underground. It is
probably about 100 feet long.

I'd love to trace the break so I can dig it up next time I visit. We suspect
that a splice was made in the wire someplace that may have failed.

Can anyone offer any good ideas for a way to locate the break without digging
the whole thing up? Maybe something using a transister radio as a locator and a
relay buzzer or something as a signal source.

Bob

Bob F wrote:
My father has a underground wire to a panel in his garage from his
house. One lead of the 220V service has apparently "opened" somewhere
underground. It is probably about 100 feet long.

I'd love to trace the break so I can dig it up next time I visit. We
suspect that a splice was made in the wire someplace that may have
failed.
Can anyone offer any good ideas for a way to locate the break without
digging the whole thing up? Maybe something using a transister radio
as a locator and a relay buzzer or something as a signal source.


There are cheap voltage proximity detectors (I've got one about the size of
a pen); they cost about $10.

You can do a binary sort. Dig down to the cable at the 50' point. Any
voltage? If not, the break is between the 50' mark and the source. Move
toward the source to the 25' mark and dig down to the cable again.

Rinse. Lather. Repeat.

"HeyBub" wrote in message
...
Bob F wrote:
My father has a underground wire to a panel in his garage from his
house. One lead of the 220V service has apparently "opened" somewhere
underground. It is probably about 100 feet long.

I'd love to trace the break so I can dig it up next time I visit. We
suspect that a splice was made in the wire someplace that may have
failed.
Can anyone offer any good ideas for a way to locate the break without
digging the whole thing up? Maybe something using a transister radio
as a locator and a relay buzzer or something as a signal source.


There are cheap voltage proximity detectors (I've got one about the size
of a pen); they cost about $10.

You can do a binary sort. Dig down to the cable at the 50' point. Any
voltage? If not, the break is between the 50' mark and the source. Move
toward the source to the 25' mark and dig down to the cable again.

Rinse. Lather. Repeat.

A good idea but may not work if the break is only in the neutral wire. It
might be possible to locate a neutral break by temporarily reversing the
wires so the neutral is hot.

Don Young

"Don Young" wrote in message
...

"HeyBub" wrote in message
...
Bob F wrote:
My father has a underground wire to a panel in his garage from his
house. One lead of the 220V service has apparently "opened" somewhere
underground. It is probably about 100 feet long.

I'd love to trace the break so I can dig it up next time I visit. We
suspect that a splice was made in the wire someplace that may have
failed.
Can anyone offer any good ideas for a way to locate the break without
digging the whole thing up? Maybe something using a transister radio
as a locator and a relay buzzer or something as a signal source.


There are cheap voltage proximity detectors (I've got one about the size of a
pen); they cost about $10.

You can do a binary sort. Dig down to the cable at the 50' point. Any
voltage? If not, the break is between the 50' mark and the source. Move
toward the source to the 25' mark and dig down to the cable again.

Rinse. Lather. Repeat.

A good idea but may not work if the break is only in the neutral wire. It
might be possible to locate a neutral break by temporarily reversing the wires
so the neutral is hot.

I can get to the wires at either end. for connections or re-connections.

Bob

"shiver" [email protected] wrote in message
...
"HeyBub" wrote in
:

Bob F wrote:
My father has a underground wire to a panel in his garage from his
house. One lead of the 220V service has apparently "opened" somewhere
underground. It is probably about 100 feet long.

I'd love to trace the break so I can dig it up next time I visit. We
suspect that a splice was made in the wire someplace that may have
failed.
Can anyone offer any good ideas for a way to locate the break without
digging the whole thing up? Maybe something using a transister radio
as a locator and a relay buzzer or something as a signal source.


There are cheap voltage proximity detectors (I've got one about the
size of a pen); they cost about $10.

You can do a binary sort. Dig down to the cable at the 50' point. Any
voltage? If not, the break is between the 50' mark and the source.
Move toward the source to the 25' mark and dig down to the cable
again.

Rinse. Lather. Repeat.

Binary search is the best way to physically minimize your effort.
If you have any skill with electronics, you can try this:
http://www.uoguelph.ca/~antoon/circ/foxhound.html
Or, just get the equipment from Triplett.

That's a helpful reference. I might even have the parts to breadboard that.

OR, I have a signal generator that starts at 100KHz. I'll have to experiment
with that.

Bob

Bob F wrote:
My father has a underground wire to a panel in his garage from his house. One
lead of the 220V service has apparently "opened" somewhere underground. It is
probably about 100 feet long.

I'd love to trace the break so I can dig it up next time I visit. We suspect
that a splice was made in the wire someplace that may have failed.

Can anyone offer any good ideas for a way to locate the break without digging
the whole thing up? Maybe something using a transister radio as a locator and a
relay buzzer or something as a signal source.

Probably most reliable is to rent a cable detector from the local rental
place. I'm fortunate a friend who used to do sprinkler systems has one
I can borrow on occasion. I suspect ones like his aren't that expensive
if it's something you might use more than once, but I really don't know.

It was reasonably successful in isolating a break in the feeder to one
of the waterers in the corrals last year -- we got within a couple of
feet at 3-ft depth on the one end. I was never able to find the other
end, though, even starting from that known point. In this case, it was
Al cable and the sheath had failed. Being in the feedlot, even though
that deep, it had been failed long enough a couple of feet had been
dissolved entirely by the strong urea solution in the water, even at
that depth.

But, it did find the starting point which saved quite a bit of time...

--

In article ,
"Bob F" wrote:

We suspect that a splice was made in the wire
Can anyone offer any good ideas for a way to locate the break

If the open is "clean", that is, NOT grounded or crossed, you can determine
the distance-to-open from either direction and use that information to
determine where to dig. Of course, such testing generally requires the use of
a TDR (time domain reflectometer), not something found in the average DIYer's
toolkit.

If the open is "dirty" (grounded), the use of a ground fault locator is in
order. Of course, that is also something not found in the average DIYer's bag.

I expect that neither of these testers is available at even the more
widely-stocked rental place. Even if they were, successfully using such
sophisticated test equipment is probably beyond the capability of a
first/only-time user.

You would well to consider REPLACING the line.

Any effort made and expense incurred in repairing the existing line, if
directed instead at replacing the line, would effectively reduce the cost of
replacement. ...and that is IF you are successful in repairing the old line -
certainly not a "given". Good luck.
--

JR

Climb poles and dig holes
Have staplegun, will travel

"Jim Redelfs" wrote in message
...
In article ,
"Bob F" wrote:

We suspect that a splice was made in the wire
Can anyone offer any good ideas for a way to locate the break

If the open is "clean", that is, NOT grounded or crossed, you can determine
the distance-to-open from either direction and use that information to
determine where to dig. Of course, such testing generally requires the use of
a TDR (time domain reflectometer), not something found in the average DIYer's
toolkit.


Any easy way to fake a TDR with a signal generator and an oscilloscope?

Bob

"Bob F" wrote in message
. ..

"Jim Redelfs" wrote in message
...
In article ,
"Bob F" wrote:

We suspect that a splice was made in the wire
Can anyone offer any good ideas for a way to locate the break

If the open is "clean", that is, NOT grounded or crossed, you can determine
the distance-to-open from either direction and use that information to
determine where to dig. Of course, such testing generally requires the use of
a TDR (time domain reflectometer), not something found in the average DIYer's
toolkit.


Any easy way to fake a TDR with a signal generator and an oscilloscope?

Bob


Yes...

"Rick" wrote in message
...

"Bob F" wrote in message
. ..

"Jim Redelfs" wrote in message
...
In article ,
"Bob F" wrote:

We suspect that a splice was made in the wire
Can anyone offer any good ideas for a way to locate the break

If the open is "clean", that is, NOT grounded or crossed, you can determine
the distance-to-open from either direction and use that information to
determine where to dig. Of course, such testing generally requires the use
of
a TDR (time domain reflectometer), not something found in the average
DIYer's
toolkit.


Any easy way to fake a TDR with a signal generator and an oscilloscope?

Bob


Yes...

Thanks!

Bob

"Bob F" wrote in message
...

"Rick" wrote in message
...

"Bob F" wrote in message
. ..

"Jim Redelfs" wrote in message
...
In article ,
"Bob F" wrote:

We suspect that a splice was made in the wire
Can anyone offer any good ideas for a way to locate the break

If the open is "clean", that is, NOT grounded or crossed, you can determine
the distance-to-open from either direction and use that information to
determine where to dig. Of course, such testing generally requires the use
of
a TDR (time domain reflectometer), not something found in the average
DIYer's
toolkit.


Any easy way to fake a TDR with a signal generator and an oscilloscope?

Bob


Yes...

Thanks!

Bob

You're welcome...


Do a search of TDR with a 555 timer, etc..then find or measure the characteristic
impedance and velocity factor of the cable. That might get you close, assuming you know
how the cable is run. If not, an RF generator and radio can trace the location.

Or just dig like others suggest.

In article ,
"Bob F" wrote:

Any easy way to fake a TDR with a signal generator and an oscilloscope?

Possibly, but that is beyond MY capabilities. I'm just a telco grunt that
USES the equipment. I know little about HOW it works. It took all I could
muster to remember that I want to recommend a TDR and, even more, what the
acronymn stands for. grin Please let us know how it ends up.
--

JR

On Nov 5, 10:56 pm, "Bob F" wrote:
My father has a underground wire to a panel in his garage from his house. One
lead of the 220V service has apparently "opened" somewhere underground. It is
probably about 100 feet long.

I'd love to trace the break so I can dig it up next time I visit. We suspect
that a splice was made in the wire someplace that may have failed.

Can anyone offer any good ideas for a way to locate the break without digging
the whole thing up? Maybe something using a transister radio as a locator and a
relay buzzer or something as a signal source.

Bob

Before digging I'd try something along these lines.
Disconnect the 3 wires (Assuming it is North America? two hot and one
neutral???) wires at both ends. Leave any ground connected.
Using a multimeter that has a 'capacitance measurement' measure the
capacitance of each wire with reference to the ground wire from both
ends.
If you find that say wire A has 0.2 microfarads and wire B has 0.1
micro farads and is roughly the same ratio from both ends B is broken
somewhere around the middle. Etc. We have an electricians quality DMM
(Digital multimeter) that measures capacity. You may be able to
borrow?
Have never done this, but many years ago did so using a 'telephone
Test board' meter and DC supply reversing switch keys, to find open
circuits in telephone lines. Wet leakage to ground and stray currents
often made it difficult though.
Any help?

"terry" wrote in message
ups.com...
On Nov 5, 10:56 pm, "Bob F" wrote:
My father has a underground wire to a panel in his garage from his house. One
lead of the 220V service has apparently "opened" somewhere underground. It is
probably about 100 feet long.

I'd love to trace the break so I can dig it up next time I visit. We suspect
that a splice was made in the wire someplace that may have failed.

Can anyone offer any good ideas for a way to locate the break without digging
the whole thing up? Maybe something using a transister radio as a locator and
a
relay buzzer or something as a signal source.

Bob

Before digging I'd try something along these lines.
Disconnect the 3 wires (Assuming it is North America? two hot and one
neutral???) wires at both ends. Leave any ground connected.
Using a multimeter that has a 'capacitance measurement' measure the
capacitance of each wire with reference to the ground wire from both
ends.
If you find that say wire A has 0.2 microfarads and wire B has 0.1
micro farads and is roughly the same ratio from both ends B is broken
somewhere around the middle. Etc. We have an electricians quality DMM
(Digital multimeter) that measures capacity. You may be able to
borrow?
Have never done this, but many years ago did so using a 'telephone
Test board' meter and DC supply reversing switch keys, to find open
circuits in telephone lines. Wet leakage to ground and stray currents
often made it difficult though.
Any help?

I had a meter that measured capacitance, but it died. But this is definately
worth checking out. Thanks.

Bob

"Bob F" wrote in message
. ..
My father has a underground wire to a panel in his garage from his house.
One lead of the 220V service has apparently "opened" somewhere
underground. It is probably about 100 feet long.

I'd love to trace the break so I can dig it up next time I visit. We
suspect that a splice was made in the wire someplace that may have failed.

Can anyone offer any good ideas for a way to locate the break without
digging the whole thing up? Maybe something using a transister radio as a
locator and a relay buzzer or something as a signal source.

Bob




Not exactly homebrew, but a "time domain reflectometer" will do the job.
It's a piece of highly specialized equipment.

http://en.wikipedia.org/wiki/Time-domain_reflectometer

"Bob F" wrote in message
. ..
My father has a underground wire to a panel in his garage from his house. One
lead of the 220V service has apparently "opened" somewhere underground. It is
probably about 100 feet long.

I'd love to trace the break so I can dig it up next time I visit. We suspect
that a splice was made in the wire someplace that may have failed.

Can anyone offer any good ideas for a way to locate the break without digging
the whole thing up? Maybe something using a transister radio as a locator and
a relay buzzer or something as a signal source.

Thanks everyone for all the ideas. I did some experimentation today with my
signal generator and an AM radio. I'm hopeful this will work, and hopefully will
get over to try it for real this weekend.

Bob