100+ volts down earth ????

[JD6400]

Just had a call from two of our men who are testing an agricultural dealership , they have found 100 + volts on one of the lighting cpc's .
To cut a long story short , they have cut around 2 and a half meters out of the 10 meter the circuit ( 1.5 T+E ) and have it laid on the floor . They say that they are getting +500 between all conductors ( Two different Fluke MFT's ) , but when they put power on it ( without connecting the cpc either end , they are still getting 100 + volts on it !

Any thoughts !????

 

[JD6400]

I hear what you all are saying and appreciate the input , but it is on a 2.5m length of cable .
Would that be long enough for this to happen ?

 

[Specialist]

In a word yes, tell them to connect 1 end of the cpc to a good earth and see what happens to the voltage.

 

[Specialist]

No not seriously!!! I know what one is just to young to have had the pleasure of using one! 38

Brilliant bit of kit, never leave home without mine lol.

 

[Corpy76]

Brilliant bit of kit, never leave home without mine lol.

Whats the advantages over a digital one?

 

[JD6400]

I have to admit that they did , and as expected it did disappear .
But it apparently created quite a spark on the whole circuit .
I originally suggested that they have a fair few fluorescents in the place , but none were on at the time .
It is the first time I have come across this on such a scale and especially on such a short length of cable .

 

[Marvo]

I could easily understand it if there were fluorescent fillings connected, it's fairly likely they'd have surge suppressors which might leak a little to earth.

 

[Corpy76]

Re wire it c if it goes it's only 2.5 m

 

[Specialist]

I was talking about the short length actually, but on a large circuit I would have expected a bit of a splash. Like discharging a big capacitor to ground.

 

[JD6400]

Re wire it c if it goes it's only 2.5 m

Unfortunately the affected circuits cover a fair area , the 2.5m is just a length of the cable they managed to cut out of the affected circuit so that they could test it within known parameters as it were .

 

[Specialist]

Whats the advantages over a digital one?

An analogue meter has a much lower input impedance than a digital, usually in the order of 20 kilohms for a quality meter. So it puts a greater load on the circuit when voltage testing, when looking for ghost voltages for example the analogue meter won't register them where a digital will.

 

[Corpy76]

Unfortunately the affected circuits cover a fair area , the 2.5m is just a length of the cable they managed to cut out of the affected circuit so that they could test it within known parameters as it were .

Sry I struggle with reading! That should be sorted after I've finished the spot the dog books I'm on with at the moment!

 

[JD6400]

I must add that I am about 150 miles away from this job at the moment and have not been to site yet , to see it myself .

 

[JD6400]

Sry I struggle with reading! That should be sorted after I've finished the spot the dog books I'm on with at the moment!

I was not sure if you were just havin a laugh to be honest , so I would not worry . :earmuffs:

 

[Marvo]

No not seriously!!! I know what one is just to young to have had the pleasure of using one! 38

Apologies, I wasn't sure if you were joking or not. Every electrician should carry one, they aren't prone to the confusing readings you get with the MFT's and they have several other advantages as well.

 

[Corpy76]

Apologies, I wasn't sure if you were joking or not. Every electrician should carry one, they aren't prone to the confusing readings you get with the MFT's and they have several other advantages as well.

Do you have to spend a fortune on batteries or use rechargeable ones that last one test or are they wind up! Seriously my mate brought one to work once and you wound it up!