IR results

[steve.t.]

hi

just wondering if anyone could help me understand these results that i am testing in my own property on a lighting circuit with all loads removed.
N/E 97.8M
L/E 92.6M
L/N 4.42M

Any help would be great thanks

 

[Mr Mark Sparks]

how old is the installation they could be genuine results not everything good will be of the scale
a while ago i put a pic on here of a brand new es lampholder with the lamp out and disconnected it had low readings across all 3 will see if i can find it

 

[Mr Mark Sparks]

how old is the installation they could be genuine results not everything good will be of the scale a while ago i put a pic on here of a brand new es lampholder with the lamp out and disconnected it had low readings across all 3 will see if i can find it

look at this http://www.electriciansforums.net/electrical-forum-general-electrical-forum/6794-follow-up.html

 

[ezzzekiel]

well theyre acceptable readings, record and move on.

lower l/n could indicate something still attached or slight problem with cabling somewhere, the real issue starts when its below required value and you have to trace it out.

 

[steve.t.]

it's old colours of black and red so prob about 10 to 15 years old

 

[telectrix]

the lower L/N reading could also be due to a socket

 

[ezzzekiel]

Strange world ir testing, best of not to dwell on it unless readings are lower than minimum requirements or it's causing problems within the installation unless of course you have the time to rip the place apart

 

[Deleted member 26818]

When you tested between L&N, did you hold the test button down for any length of time?
If so, did the reading alter?

 

[telectrix]

sorry, missed the " lighting" bit. could just be slight dampness in walls around switches.

 

[steve.t.]

yes the reading was altering

 

[topquark]

yes the reading was altering

In that case get your pipe and deerstalker as a little more investigation is warranted.

 

[steve.t.]

trying to break the circuit down for some practice but when i connect L/N at one end and IR test from the other end of cable i get a dead short.
thank's for all your help

 

[sparkinlee]

If you've connected L/N at one end and then IR test between L & N at the other end, a dead short is what you'd expect!

If you want to break the circuit down you need to open up the light fittings, disconnect the loop in / loop out and leave them open circuit so you can IR test each leg of the cable.

You might find that each leg of cable is fine, and the problem is with one of the fittings.

 

[Deleted member 26818]

Do you have two way switches anywhere?
Have you tried the IR test with the 2 way switches in different positions?
Have you tried switching the MCBs off for other lighting circuits?
Is it possible that what you have is a shared neutral?

 

[sparkinlee]

...don't mention the dreaded shared neutral... suddenly everybody's got one