Strange IR results.....

[raustin]

Hi there

Whilst carrying out a PIR on a mobile home, the IR results for the ring came up low, between 2 - 3M ohms. All other circuits where fine.

Broke the ring into 2 legs and then split that down until we found the length of cable that was causing the low readings, or so I thought.

The run that we thought was at fault, was actually OK, it was the very first run from the CU to the 1st socket.

When we IR'd that single run of cable it passed the IR at 500V with over 2000M ohms, but when we connected it to a new piece of cable, the IR results were back down to 2 - 3M ohms.

Once we had replaced that 1st run of cable and connect the ring back up, the IR results were above 2000M ohms.

Can anyone explain why the IR was OK when we only tested the single run of cable by itself?

But when we connected it to any other cable the IR results were low?

Cheers
Rich

 

[Octopus]

Had something similar once.Turned out that the socket was the "offending" part

 

[raustin]

Had something similar once.Turned out that the socket was the "offending" part

Yeah thought that so tried a new socket and had the same results. Even bypassed the socket and used a choc block. In the end had to get under the mobile home and run a new length of cable. Really odd!

 

[MarkieSparkie]

Hi raustin, was the 1st socket in a metal back-box, if so when the cables were connected to the socket and it was screwed to the back-box, one or more cores may have had a leakage path to the back-box and CPC. This path ceased to exist with the socket disconnected.

 

[raustin]

Hi raustin, was the 1st socket in a metal back-box, if so when the cables were connected to the socket and it was screwed to the back-box, one or more cores may have had a leakage path to the back-box and CPC. This path ceased to exist with the socket disconnected.

Hi Markie, yeah it did have a metal back box, but I got the same readings when I used a terminal block to connect another piece of cable, bypassing the socket and back box.