Easily locating short in cable

Question

What is the easiest way to pinpoint where a T&E cable has been damaged in a wall/ceiling - probably due to rodents! 
 I understand in larger highways lighting networks they use a thumper and detect the RF emissions to pinpoint the fault. 
 Is there a similar way that this can be done on a domestic install without very expensive equipment? Perhaps with a signal generator and a small loop antenna attached to a scope?

AMK · Accepted Answer

Hi, I use a Fluke 2042R cable locator and receiver, which I utilise for identifying short circuits. 
 Andrew

Chris Pearson · Answer

That must mean that you have identified which section of the ring is damaged. 
 I agree with Broadgage that it would best to replace the whole section. If you are going to have to dig out at least a couple of feet, making it six feet won't look much worse, and the decoration will still have to be made good. 
 There is also the question of joining the cable, which is avoided if the whole section is replaced. 
 You may be able to get an idea where the short is by measuring the resistance of the two portions of the damaged section - its distance along the section will be proportional to the resistance. Granted your low resistance ohmmeter may not make much of a distinction, but it should give an idea.

Sergio Fernandez · Answer

If you have a MFT (Multi Function Tester) used by the average electrician you could try 
 link out the CpC and Line then get your R1 R2 
 then use chart on Guidance note 3 or onsite guide for copper resistance and reverse the maths. 
 so as an example if R1 R2 equals 0.07 and you are use 2.5mm2 CSA it give you a value of 19.51 so 0.07 / 19.51 times by 1000 gives you of 3.6 so the calculation would suggest 3.6 meters for the fault. There are various YouTube tutorials about it. 
 
 Hope this helps

Easily locating short in cable

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