Puzzled

[Victor]

Had a really weird situation today. Having installed all the wiring and new consumer unit for a full rewire, I today came to test the last circuit which was the downstairs lights. Tested continuity which was fine as was insulation resistance, upon testing for loop impedance, I got a low voltage error message which upon investigation showed only 185 volts between first and 2nd light points. Result was I ended up having to take up the floorboards and replace the cable which looked totally normal and undamaged. Has anyone else had anything like this happen to them?

 

[TJ Anderson]

What do you mean exactly by 185V between first and second points. Can you clarify that? Are you saying you had 240V at the first fitting and 185V at the second?

 

[Victor]

Exactly that, the cable between the two points would not pass more than 185 volts

 

[Lucien Nunes]

Tested continuity which was fine

Did you test both L & N? If not, the N conductor might have been internally broken. the 185V was probably arbitrary and just indicative of a high resistance, if you had used a different meter or put more load on it probably would have changed.

 

[mache]

Did you keep the cable you removed to test as a matter of interest?????

 

[TJ Anderson]

If you had 240v across L&N at the first fitting and 185V across L&N at the second fitting I would say you lost the neutral, either the cable had a break or a poor termination.

 

[Octopus]

Did you test L-E at the 2nd point? Did you do an R2 on all 3 cores between the 2 points?

 

[Victor]

Tested both L and N with no high readings, even did a continuity test on the cable once I have removed and replaced it, again no high readings, that what is so weird.

 

[Leesparkykent]

Tested both L and N with no high readings, even did a continuity test on the cable once I have removed and replaced it, again no high readings, that what is so weird.

Must be a poor termination then on the neutral.

 

[TJ Anderson]

Did you test L-E at the 2nd point? Did you do an R2 on all 3 cores between the 2 points?

That is what I was thinking. I think he just did R1+R2 so the neutral was not dead tested.

 

[TJ Anderson]

Tested both L and N with no high readings, even did a continuity test on the cable once I have removed and replaced it, again no high readings, that what is so weird.

If you still have that leg of cable put your continuity tester on the neutral at either end, then flex the cable around and see what happens on your scale.

 

[Victor]

Will test the length of cable again in the morning and see what happens when I flex it with a meter on it. Thanks guys for all your comments.