USING THE TIMCO
CONTINUITY TESTER
The Timco Continuity Tester is the best kept secret of any seasoned underground fault locator. This simple instrument will save countless hours of circuit diagnostic time, because it will tell you whether or not the cable fault is contacting ground or if it is isolated in a splice or located in an above ground device.
It Is Not The Same...
Whenever I mention the Continuity Tester the reaction is always the same "I can do that with my multimeter".
We are not talking about an instrument here that tells you if a cable or wire has continuity throughout, a measurement such as this is relatively worthless for underground cable fault locating because a faulted cable will show some continuity unless the cable is fully cut. A faulted cable will also carry voltage, often full voltage, until a load is applied.
So What Does It Do?
The Timco Continuity Tester, with a simple two-wire connection to a deenergized cable, measures that cable's potential to ground. Why is this an important measurement? Let me give you three easy examples:
Situation 1:
You have tested your section of cable under a load and you have determined that a fault exists. You have traced out your circuit and you have isolated the faulted section of cable. You attempt to locate the fault underground with a Spitfire or whichever tool you are using, but that tool refuses to detect the existence of a fault. You are not seeing any needle deflection on your meter. You move all of your equipment to the opposite end of the cable and try again, and get the same results. Back and forth you go, until you give up and start digging random holes. You know that the cable is faulted, but why can't your locating equipment pick it up?
The fault is inside of an underground splice
The fault is in duct or conduit
The fault is inside of the street light pole
The fault is in the pole riser
The fault is in an underground enclosure or hand box
The cable has been cut and taped up
The cable has not been terminated in a transformer
and my favorite - The cable has pulled out of the lug at the meter but the tape holds it together
Sure, none of these real-life faults are especially easy to locate, but how much time would you have saved if you knew that the cable fault was not contacting ground before you used the wrong tools and excavated for nothing? The Timco Continuity Tester would have told you ahead of time where to search for the fault and which equipment to use!
Situation 2:
You have "inherited" an underground cable fault from another crew, who was called away for an emergency. The fault is on a basic two phase house service. When you arrive you find that the first crew has removed all of the circuit cables from both the transformer and the meter box, and has not marked which cable was in trouble. How do you know which cable to fault locate on? Sure, you can reconnect each cable and take voltage measurements on each one - but what if the faulted cable is actually shorted and will cause an arc flash when you connect it? You could even connect both cables together and fault locate both at the same time, sending your signal from your equipment all over the place. Or better yet, you could do this the safe and easy way by simply testing the cables with the Continuity Tester!
Situation 3:
I have seen this happen so many times it is ridiculous. You do everything right - you trace and isolate the circuit and locate the fault easily. You cut out the faulted section and splice in the new cable, backfill your excavation perfectly and go to load test the end of the circuit. And discover that a second fault exists somewhere on the circuit!
So now, not only do you have to isolate the circuit again and get all of the fault locating equipment out and hooked up - you have already spliced and backfilled a perfect isolation spot!
Multiple underground cable faults are common on street light circuits, and are not unheard of on services and other underground electric circuits. A simple and quick measurement with the Continuity Tester in both directions from your original fault location before splicing the cable would have told you that another cable fault existed. How much time and frustration would that have saved?
The Timco Continuity Tester Is One Of The Best Assets That The Professional Fault Locator Can Have In His/Her Arsenal, Second Only To The Spitfire And A Good Multimeter
How To Use The
Continuity Tester
The main requirement in using the Continuity Tester is that the cable to which it is to be connected must not be carrying any voltage whatsoever.
Connecting the Continuity Tester to any energized cable, regardless of the voltage, will damage the instrument beyond repair.
The cable to which the Continuity Tester is to be connected must also be fully isolated from any potential paths to ground. Disconnect any devices such as fixtures, ballasts, and meters from the circuit.
*NOTE, if the batteries in the Continuity Tester are low you may not see a full reading on the analog meter. If the meter indicates a reading of 60 or above it can still be used, just remember that the highest measurement during this test will be the highest measurement possible, and further measurements should take this in to account.
Connect the BLACK clamp to a driven ground rod
Connect the RED clamp to the cable that you want to test
Note the reading on the analog meter:
0 - 30, the cable is clear and is not contacting ground at any point
*If you have determined that a fault does exist on the cable and the Continuity Tester shows a clear reading, your fault is not contacting ground and therefore neither the Spitfire or any other equipment will be able to detect the fault. Check the conditions under Situation 1 above for possible answers.
30 - 60, this reading indicates dirty cable. This could indicate deteriorated insulation, old splices, or most likely - a cable fault. These should be easily detected by the Spitfire.
60 - 120, is a full reading and indicates an open fault or possibly a shorted cable. These should be easily detected by the Spitfire.
* A full reading can also be caused by devices or equipment connected to the circuit, providing a path to ground. If the measurement is questionable re-check the circuit for isolation.
The Continuity Tester is a safe, versatile, rugged, and easy to use instrument that saves considerable time and prevents frustration during underground electric cable fault diagnosing.
next - The Hill Of Potential Method