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Thread: Testing continuity in a very long wire

  1. #1
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    Default 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

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    Default 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.

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    Default 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.

    Chad
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    Default 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

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    Default 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)

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    Default Re: Testing continuity in a very long wire

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

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    Default 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.

    Don't ask about respooling the wire though.

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    Default Re: Testing continuity in a very long wire

    Quote Originally Posted by BrianW View Post

    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.

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    Default 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. #10
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    Default 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. #11
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    Default 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 !

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    Default Re: Testing continuity in a very long wire

    Quote Originally Posted by Paul Girouard View Post
    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.

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    Default 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.
    When you can take the pebble from my hand, it will be time for you to leave.

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    Default Re: Testing continuity in a very long wire

    Quote Originally Posted by Bob (oh, THAT Bob) View Post

    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?

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    Default Re: Testing continuity in a very long wire

    Quote Originally Posted by BrianW View Post

    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?

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    Default 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?
    Complicated problems usually have simple solutions - which are almost always wrong.

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    Default Re: Testing continuity in a very long wire

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

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    Default Re: Testing continuity in a very long wire

    Quote Originally Posted by Paul Girouard View Post
    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.
    When you can take the pebble from my hand, it will be time for you to leave.

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    Default Re: Testing continuity in a very long wire

    Quote Originally Posted by ripley699 View Post
    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
    did I really say that out loud.........

  20. #20
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    Default 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. #21
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    Default Re: Testing continuity in a very long wire

    Wear dogs collar.

    Walk wire.

    When you stop getting electrocuted, it's broken.


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    Default 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

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    Default 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.
    Never trust a man with a clean workshop.

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    Default Re: Testing continuity in a very long wire

    Quote Originally Posted by Bob (oh, THAT Bob) View Post


    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

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    Default 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

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    Default Re: Testing continuity in a very long wire

    Quote Originally Posted by Paul Girouard View Post
    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.

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    Default Re: Testing continuity in a very long wire

    Quote Originally Posted by Paul Girouard View Post
    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.
    When you can take the pebble from my hand, it will be time for you to leave.

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    Default Re: Testing continuity in a very long wire

    Quote Originally Posted by Rick Starr View Post

    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. #29
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    Default Re: Testing continuity in a very long wire

    Quote Originally Posted by Bob (oh, THAT Bob) View Post


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

    Quote Originally Posted by Paul Girouard View Post
    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. #31
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    Default Re: Testing continuity in a very long wire

    Quote Originally Posted by BrianW View Post



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

    Sweet, I passed the test.

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    Default 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. #34
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    Default 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.
    1947 Nordic Folkboat "Nina"

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    Default Re: Testing continuity in a very long wire

    Quote Originally Posted by BarnacleGrim View Post
    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?

    Quote Originally Posted by Brian Palmer View Post
    .. 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.
    ....
    Complicated problems usually have simple solutions - which are almost always wrong.

  36. #36
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    Default Re: Testing continuity in a very long wire

    Years ago it was common on complex machines with multiple panels to wire between with solid wire to terminal strips. Many times to many to count intermittent opens would occur only to find the solid wire had broken in the insulation. As back then most runs where in EMT it was next to impossible to find that barely open wire by means of an injected signal. Hi-Pot testing would usually find the culprit but many times one guy on one end and one on the other yanking on it was the only way. When building panels now I never use solid wire.
    It does look pretty with all the neat bends but when it fails its a huge pain in the arse.

  37. #37
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    Default Re: Testing continuity in a very long wire

    Isn't it good enough to just have faith that the wire is OK?

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