High R1+R2 but acceptable Zs

[Mspark2987]

Hi everyone. Did a test last week and sorting the paperwork. On the downstairs lighting circuit I got an R1+R2 reading of 3.35 but a Zs of 0.90. Normally I'd go looking for a loose connection somewhere myself but the company I work operates in a way where I've got a limited time to do the inspection and then someone is sent behind me to put anything right. If I add my Ze to that R1+R2 it is within the maximum permitted Zs for the circuit. But to be sure I measured the Zs.
Would you put the higher than expected R1+R2 reading down as a C3 or C2?

Thanks

 

[Harry_P]

Hi everyone. Did a test last week and sorting the paperwork. On the downstairs lighting circuit I got an R1+R2 reading of 3.35 but a Zs of 0.90. Normally I'd go looking for a loose connection somewhere myself but the company I work operates in a way where I've got a limited time to do the inspection and then someone is sent behind me to put anything right. If I add my Ze to that R1+R2 it is within the maximum permitted Zs for the circuit. But to be sure I measured the Zs.
Would you put the higher than expected R1+R2 reading down as a C3 or C2?

Thanks

You did a test so you just need to report what you found and let whoever comes after you find out why the reading is not as expected, and I think it's an F1 further investigation needed

 

[SJD]

You don't mention what type of property this was, or what type of light.

In a domestic property, you can often roughly tell the order a lighting circuit was wired from the R1+R2 readings. And an unusually high reading will often stand out as being a bit odd. If a ceiling rose, then I'd typically check the connections are tight and remeasure, bearing in might the issue be at the previous fitting.

But it sounds like you are not given time to interpret the results as you test, though one reading quite a lot higher than the others might stand out.

I'd mark it as FI on the EICR.

 

[TJ Anderson]

You say downstairs lighting.....house I assume?

It's gonna be 1mm/1mm or 1.5mm/1mm 6242 cable I also assume

How long is circuit approximately?
Depending on temp when tested, but it wont affect it much, based on R1+R2 of 3.35 Ohms, if it was 1mm, your circuit would be 93M long......If it was 1.5mm, it would be 111M long. Not sure how you wired it, can you clarify?

Did you disconnect cpc from main earthing terminal when you tested R1+R2? Have you considered parallel paths with the Zs?

 

[johnduffell]

I would say the lighting circuit probably has a class 1 light fitting screwed to something that's bonded. You can't exclude that from the live tests, that's why the dead test is the gold standard.