# Thread: Testing continuity in a very long wire

1. ## Testing continuity in a very long wire

I need to test whether there is a break in our electric dog fence. It is a buried 18 g solid copper wire that is about 600 feet long.

Can I test whether there are any breaks using a flashlight bulb and a 1.5 volt battery (i.e., does the bulb light?), or is there too much resistance in a wire that long for such a small battery?

Any other easy suggestions?

Obviously, I don't do too much electronics. I don't have a multi-meter or anything like that.

Thanks,

Brian

2. ## Re: Testing continuity in a very long wire

18 gauge wire has .00751 ohms/ft. So 600 feet would give you a resistance of about 4.5 ohms. Since you don't know the resistance of the bulb, and therefore the current draw, you can't determine the line voltage drop over the 600 feet. The drop might be enough to prevent the bulb from glowing bright enough to detect, even if the wire is good.

An easier way is to use an ohmmeter, which will read 4.5 ohms if the wire is intact, and infinite ohms if the wire is broken. Make sure all power is off when using the ohmmeter, and that both ends of the wire are disconnected from everything else, otherwise you might be reading the resistance of an unknown parallel circuit.

3. ## Re: Testing continuity in a very long wire

Find yourself a TA-312, hook it up to one end (2 separate strands) and find you a teenager to hold both strands on the other end. You than crank on the handle of the 312 for a bit. If he starts dancing you know you are good.

4. ## Re: Testing continuity in a very long wire

You could get a cheap multimeter for about 10 bucks. It'll come in handy again sometime. If I'd had mine on the boat last night I might have been able to figure out why my engine wouldn't start. As it was on shore I just jumped it with a piece of wire and off we went.

Steven

5. Gareth
Join Date
Jan 2003
Location
Southern Maine
Posts
20,024

## Re: Testing continuity in a very long wire

Use a 3V battery or two 1.5 in series and then stick the bulb in there.

Better still get a cheap multimeter (digital about \$15)

6. Banned
Join Date
Mar 2008
Posts
275

## Re: Testing continuity in a very long wire

Is this buried wire supposed to be fully insulated from the ground?

7. ## Re: Testing continuity in a very long wire

You can get a 700ft roll of .020 safety wire here...

http://www.pegasusautoracing.com/pro...p?Product=3129

...connect it to one end, string it to the other end, and hook a multimeter inbetween.

On aircraft, and other conducting metal structures, you can use two multimeters to test a long wire run, touch the wire at each end with the positive lead and the ground lead to the airframe to complete the circuit. Heck, even a wire with an alligator clip on each end could be substituted for one of the meters.

8. Banned
Join Date
May 2005
Location
Whidbey Island , Wa.
Posts
15,282

## Re: Testing continuity in a very long wire

Originally Posted by BrianW

On aircraft, and other conducting metal structures, you can use two multimeters to test a long wire run, touch the wire at each end with the positive lead and the ground lead to the airframe to complete the circuit. Heck, even a wire with an alligator clip on each end could be substituted for one of the meters.
You where a mech right whats the two meter thing about? On a A/C the frame is always the ground , short one end of the wire to ground ( the airframe), attach the other end to one of the meter leads , the other meter lead then goes to ground ( the airframe ) if the meter reads you have potential for continuity ( a good wire) the problem is one lil strand of 22 gauge wire will "read" continuity but will NOT carry a load. A test light is the best way to test aircraft wiring.

This is why Aviation electrician's are called "one wire's" in NAVAIR , power to ground via one wire makes all electrical things work , switches and relays make a more complicated system as a whole but the basics are always power to ground.

Now not the "tron" side of the A/C but the basic power is a simple path from power to ground ( the air frame)

The OP issue is the wire he's testing is #1 single stranded and more than likely not shielded , as in bare wire. I'm not familiar with these under ground dog fences at all. But I'm guessing a megameter would be the tool to test his wire.
Last edited by Paul Girouard; 08-28-2009 at 10:59 PM.

9. Banned
Join Date
May 2005
Location
Whidbey Island , Wa.
Posts
15,282

## Re: Testing continuity in a very long wire

Does your collar have this test feature listed on this web page?

http://www.americas-pet-store.com/de...odid/1727.html

Built-In Stimulus Test Lamp feature you can insure that the shock is working by taking the collar into the radio field and pushing the Stimulus Test Button. This diverts the shock energy from the stimulus probes to the test lamp. Other collars may provide an awkward external lamp for this test, but ours is built in!

10. Banned
Join Date
May 2005
Location
Whidbey Island , Wa.
Posts
15,282

## Re: Testing continuity in a very long wire

Found this ,

Walk the line with the dog's collar in hand. Walk close enough to the line
to trip the "beeping' in the collar; when the beeps stop, you're at the
break.

Here, http://www.homegardenguides.com/gard...detection.html

11. Banned
Join Date
Jun 2009
Location
Meredith,New Hampshire
Posts
703

## Re: Testing continuity in a very long wire

Put the dog collar around your neck tightly.walk towards the wire. you'll know soon enough..

Hey,if its good for the goose .........
The biggest problem with dog fences is that it keeps my dog in ,,,doesn't keep your dog out..My dog is very well trained [a national champion ] I don't worry much about my dog ,,its your dog and the bear and fishercat in my back yard that bother me !

12. ## Re: Testing continuity in a very long wire

Originally Posted by Paul Girouard
You where a mech right whats the two meter thing about?
I think the reason 2 multimeters were (are) often used was (is)...

1. We had big tool boxes with 2 or more multimeters in them.

2. Most often the wires ended in canon plugs with corresponding small holes and recessed pins.

3. The multiple multimeter probes fit into said cannon plugs better then anything else handy. (except maybe safety wire)

And yes, I was a mechanic most my career, but the Coast Guard combined their mechanic and electrician rates, and we started doing everything but avionics stuff. I think that was a mistake, but it wasn't my choice.
Last edited by BrianW; 08-28-2009 at 11:54 PM.

13. mind melding with Meerkat
Join Date
Feb 2007
Location
Do you have a warrant?
Posts
3,849

## Re: Testing continuity in a very long wire

Digital multimeters are 3 dollars at Harbor Freight. For what you are doing, it's good enough.

14. Banned
Join Date
May 2005
Location
Whidbey Island , Wa.
Posts
15,282

## Re: Testing continuity in a very long wire

Originally Posted by Bob (oh, THAT Bob)

Digital multimeters are 3 dollars at Harbor Freight. For what you are doing, it's good enough.

Can you describe exactly how he'd use a meter to test this wire?

15. Banned
Join Date
May 2005
Location
Whidbey Island , Wa.
Posts
15,282

## Re: Testing continuity in a very long wire

Originally Posted by BrianW

I think the reason 2 multimeters were (are) often used was (is)...

1. We had big tool boxes with 2 or more multimeters in them.

What was your tool control program like? I still don't see how two meters would work in tandem, one would "read" the other potential and that would give you freaky readings. The jumper wire your mentioned is the way to TS with a meter.

2. Most often the wires ended in canon plugs with corresponding small holes and recessed pins.

Cannon is a brand of quick disconnect, yes, small holes small wire.

I'm sure you had some moron cut a plug off that needed changed and have the same moron not mark any wires before the cuts where made!

3. The multiple multimeter probes fit into said cannon plugs better then anything else handy. (except maybe safety wire)

Any wire can be a jumper. The big issue with a meter for this type of trouble shooting is the fact that single strand of wire will tell you " Yup I'm good to go!" A test light applies a load, I could tell you three or four " No \$hit " sea stories about meter tested wires that where tested as 4.0 on deck , No workie in flight or ground turn failed in operation.

Mud duck's , hoy vey!

And yes, I was a mechanic most my career, but the Coast Guard combined their mechanic and electrician rates, and we started doing everything but avionics stuff. I think that was a mistake, but it wasn't my choice.
Yes, the USN also did some combining of rates they did NOT combine AE with the other "tron" rates , like AQ , AT , AW , etc the "tron-ie / tweet" rates. That was a smart move on thier part. Aviation Everything's, we ruled the flight deck Well at least maintenance control

One of my favorite meter stories involved a E-8 AT and a LDO LTJG who was a AE before he went LDO. We had a oil pressure gripe IIRC and the wire harness that looped up and over the engine , a J52P408 Prowler motor, well we had a open wire in that harness so we had to drop the motor and replace the wire harness. They the MMCO LDO and the Echo -8 Maintenance control Chief wanted the harness and a meter. They where sure the harness was good and I was wrong, so they call me into the MMCO's office where the E-8 holding the ends of said wire pinched between his big fat finger tips and the meters reading continuity and they say " Well Girouard whats up with this ? This wire not broken!" I said " Are you guys serious?" Well the LT he's sort of PO'ed I didn't say "Sir " at some point , but as I was addressing two people , and one wasn't a "sir" I figured I had wiggle room

So what from what I've written here was my "grounds" to be some what "insubordinate"?

It's a simple question really. Well, if you know much about meter's.

This is a test in a way so what ya got?

16. ## Re: Testing continuity in a very long wire

I'd bin a pinched wire - the electrons is supposed to stay on the inside and not leak out, and a partially broken wire can heat up locally threatening the integrity of all those around it - none of which is fun..

So far we have two or three variations on a DC meter check for GO/NO GO. - on 1800 feet of wire, two questions
If it's bust - are you going to replace the whole thing?
How izz you planning to find the break?

17. Banned
Join Date
Jun 2009
Location
Meredith,New Hampshire
Posts
703

## Re: Testing continuity in a very long wire

Why isn't tyler chiming in here? he freakin knows everthing?

18. mind melding with Meerkat
Join Date
Feb 2007
Location
Do you have a warrant?
Posts
3,849

## Re: Testing continuity in a very long wire

Originally Posted by Paul Girouard
Can you describe exactly how he'd use a meter to test this wire?
Unlike early meters with several different plug-in contacts for the probe wires, the digital meters don't require moving the probe wires, there is only one plug for each on the meter.

The meter will need to have a good battery.

Set the meter to the lowest ohm range (resistance). Touch the probe ends together; you should read zero ohms (no resistance). Now use the meter probes (ends of the wires) the same as you would a test bulb. If the wire you are testing is a loop, both ends are near enough to touch one of each probe to the ends of the wire. If you don't get a reading, increase the range by 10x (the next position on the dial). Read results.

If both ends of your 600 ft line are not near each other, you will need a long wire to allow you to check your buried wire.

19. Misunderstood
Join Date
Feb 2001
Location
central, FL
Posts
13,700

## Re: Testing continuity in a very long wire

Originally Posted by ripley699
Why isn't tyler chiming in here? he freakin knows everthing?
He is busy tryin to find a website that ties this possible
broken wire with the economic collapse of the world

20. ## Re: Testing continuity in a very long wire

You need a wire tracer. It injects a signal in the wire and you walk the path with a receiver looking for a break. They are pretty cheap or if you have a phone or Lan guy nearby they might let you borrow one or do it for you cheap. If its a kink, corrosion etc. it may be difficult but I am sure once you get the hang of it things will be good.
Look for wire tracers on the internet and I don't think I would pay more than 50 bucks for one.

Sorry, had a date last night, just woke up.

21. Banned
Join Date
Sep 2008
Location
Far south of 90
Posts
2,436

## Re: Testing continuity in a very long wire

Wear dogs collar.

Walk wire.

When you stop getting electrocuted, it's broken.

22. ## Re: Testing continuity in a very long wire

Thank you all for the suggestions. There seems to be something wrong with the sending unit, and the collars we have are at least 6 years old (one is almost 10).

So, we are trying to decide whether to get just a new sending unit or a whole new kit and replace the wire as well.

I've walked to the edge of the yard plenty of times to check the charge on the collars before, BTW.

Funny story: My parents got a fence system before we did and the first two people to "sample" the shock from the collar just to see what it was like both had PhDs, my older brother and SWMBO.

Brian

23. Banned
Join Date
Feb 2000
Location
The land of reefs
Posts
32,057

## Re: Testing continuity in a very long wire

I usually find the breaks in invisible fence wires are right where someone planted a tree/shrub/flower bulb.

24. Banned
Join Date
May 2005
Location
Whidbey Island , Wa.
Posts
15,282

## Re: Testing continuity in a very long wire

Originally Posted by Bob (oh, THAT Bob)

Set the meter to the lowest ohm range (resistance). Touch the probe ends together; you should read zero ohms (no resistance). Now use the meter probes (ends of the wires) the same as you would a test bulb. If the wire you are testing is a loop, both ends are near enough to touch one of each probe to the ends of the wire. If you don't get a reading, increase the range by 10x (the next position on the dial). Read results.

If both ends of your 600 ft line are not near each other, you will need a long wire to allow you to check your buried wire.

So your solution to his problem is to buy 600 feet of new wire to test the old 600 ft. of wire?

He might as well just bury that new wire and forget the meter eh

25. Banned
Join Date
May 2005
Location
Whidbey Island , Wa.
Posts
15,282

## Re: Testing continuity in a very long wire

That link I provided say to use a radio sent to AM walk the line and when you get static sound your near the leak in the wire.

No takers on the ohm meter scenario in post 15 eh, question must have been to hard

26. ## Re: Testing continuity in a very long wire

Originally Posted by Paul Girouard
That link I provided say to use a radio sent to AM walk the line and when you get static sound your near the leak in the wire.

No takers on the ohm meter scenario in post 15 eh, question must have been to hard
Np. T mny cnsnnts, nt ngh vwls. Lst ntrst.

27. mind melding with Meerkat
Join Date
Feb 2007
Location
Do you have a warrant?
Posts
3,849

## Re: Testing continuity in a very long wire

Originally Posted by Paul Girouard
So your solution to his problem is to buy 600 feet of new wire to test the old 600 ft. of wire?

He might as well just bury that new wire and forget the meter eh
Well he could do it when it's raining. Because ground is, well, ground.

28. Banned
Join Date
May 2005
Location
Whidbey Island , Wa.
Posts
15,282

## Re: Testing continuity in a very long wire

Originally Posted by Rick Starr

Np. T mny cnsnnts, nt ngh vwls. Lst ntrst.
No , not the right answer. You must be a mech like BrianW, high speed nose picker's, they're all alike

29. Banned
Join Date
May 2005
Location
Whidbey Island , Wa.
Posts
15,282

## Re: Testing continuity in a very long wire

Originally Posted by Bob (oh, THAT Bob)

Well he could do it when it's raining. Because ground is, well, ground.
Ya but either end will read to ground, so hows that find the break/ open in the wire?

Another Mech who wants to be a AE eh High speed nose pickers, what a bunch

30. ## Re: Testing continuity in a very long wire

Originally Posted by Paul Girouard
That link I provided say to use a radio sent to AM walk the line and when you get static sound your near the leak in the wire.

No takers on the ohm meter scenario in post 15 eh, question must have been to hard
The description is a bit vague...

They where sure the harness was good and I was wrong, so they call me into the MMCO's office where the E-8 holding the ends of said wire pinched between his big fat finger tips and the meters reading continuity and they say " Well Girouard whats up with this ? This wire not broken!" I said " Are you guys serious?"
...but I'm assuming you're referring to the fact that the E8 was providing a human closed circuit?

In any case, old wiring leads to small opens which are often intermittent. They're a pain to troubleshoot.

Our tool control was pretty good. All the tool boxes in the hanger were 'shadowed' with foam cut outs. Inventoried at the start and end of every shift, and at the end of any maintenance completed in-between. Nobody went home till they were done. Any unaccounted for tools resulted in grounding the aircraft the box was used on. No box could be used on more than one plane at a time. They would and did recall flying aircraft if there was ever any doubt as to whether or not a missing tool might have been used on that plane.

31. Banned
Join Date
May 2005
Location
Whidbey Island , Wa.
Posts
15,282

## Re: Testing continuity in a very long wire

Originally Posted by BrianW

...but I'm assuming you're referring to the fact that the E8 was providing a human closed circuit?

Yup , stupid SCPO and Lt eh! I laughed my arse off when I said , "Are you guys serious???????? Take your fingers OFF the wires Senior!" The Lt. was not amused at thier error, he told me to "Get the hell out of his office!" All in some what "good" spirits, I said Aye aye Sir, all while laughing!

In any case, old wiring leads to small opens which are often intermittent. They're a pain to troubleshoot.

Roger that. Many a hour T/S intermittent wire gripes. The test light is the ticket, beats a meter for damned near every type of wire gripe, except opens, but then you know you have a open cuz nuttin works

Our tool control was pretty good. All the tool boxes in the hanger were 'shadowed' with foam cut outs. Inventoried at the start and end of every shift, and at the end of any maintenance completed in-between. Nobody went home till they were done. Any unaccounted for tools resulted in grounding the aircraft the box was used on. No box could be used on more than one plane at a time. They would and did recall flying aircraft if there was ever any doubt as to whether or not a missing tool might have been used on that plane.
Sounds like NAVAIR 4790 rules of engagement. I went to AE "A" school with , maybe it was B,EE, school Basic Electricity and Electronics, with a E-5 Mud duck. At that time and maybe still , the coasties did not get "A" schools right out of boot camp they "fleeted" guys then schooled them either at thier EAOS , or change of duty station.

32. ## Re: Testing continuity in a very long wire

Sweet, I passed the test.

33. Banned
Join Date
Jun 2009
Location
Meredith,New Hampshire
Posts
703

## Re: Testing continuity in a very long wire

Depending upon where you live and your dogs temperment, it is wise to train them off the leash.Quite often the reason a dog runs away or acts strangely when let loose is that they don't know what to do or how to act. My dog knows that she is allowed in certain areas and not in areas that ae close to the road.
I also trained her from when she was 10 weeks old that if she ever comes upon a paved road that she may not set one foot on it unless she has a leash on. she always will walk up to the road and wait for me ... but not all dogs will respond as mine does...lots of hard work in the training dept. and a bit of luck !
Last edited by ripley699; 08-30-2009 at 03:42 PM.

34. ## Re: Testing continuity in a very long wire

An excellent opportunity to give the poor dog a rest from the shock collar and train some recall instead.

35. ## Re: Testing continuity in a very long wire

Originally Posted by BarnacleGrim
An excellent opportunity to give the poor dog a rest from the shock collar and train some recall instead.
What makes you think there are dogs involved?

Originally Posted by Brian Palmer
.. the first two people to "sample" the shock from the collar just to see what it was like both had PhDs, my older brother and SWMBO.
....

Page 1 of 2 12 Last

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•