Ring circuit fault, High RN

[CopiamElectrical]

Hey there,

Sorry I’ve just joined up. I’m a qualified electrician/Electrical engineer. Recently sat my 2391-52.

My question is I had a fault which I couldn’t find or rectify during a periodic test that I carried out yesterday (tenant property) occupied.

Circuit: Ground Floor Socket
32A Ring (r1 0.42, rn 16, r2 0.71)
R2 0.42 x 1.67 = 0.701 = Good above apart from rn!

Whipped all sockets off and checked connections at db of course. Couldn’t find anything at this point. Checked all points. Last thing was left was lifting floor boards. I couldn’t find anything in between (JB, interconnection, joint) I’ve asked tenant, unfortunately no relevant answer for an indication.

Carried out a long lead test CU - rn one leg (T&E) walked around - found dead leg from one point to the next that was giving 16ohms. Point A-B.

Split ring x2 radials (20A x 2 protective devices)

Carried out the procedural
Test R1/R2
R1/RN
Confirmed polarity….

Now getting voltage fluctuations and getting some sockets working and some aren’t due to not having 230VAC at every point on “Ground Floor Socket”

I believe there could be another dead leg or broken neutral, loose or lost.

Advice people? What would you?
How would you go about it?

 

[timhoward]

Good approach so far.
Double check your CU connections just in case.
Sockets that aren’t working, test L to E for 230v to determine if problem is still the N.
Long lead test of all 3 conductors, also consider removing all accessories and IR test end to end.
I know this will/should give 0 but it can also occasionally “blow apart” the problem connection and make finding it easier (an old fire alarm service trick). If the test result suddenly rises, bingo!

There does come a point where re wiring a leg is the only sensible option - hopefully it won’t come to that!

 

[westward10]

I suspect you still have a high resistance connection on the neutral conductor.

 

[CopiamElectrical]

I suspect you still have a high resistance connection on the neutral conductor.

Correct

 

[CopiamElectrical]

Good approach so far.
Double check your CU connections just in case.
Sockets that aren’t working, test L to E for 230v to determine if problem is still the N.
Long lead test of all 3 conductors, also consider removing all accessories and IR test end to end.
I know this will/should give 0 but it can also occasionally “blow apart” the problem connection and make finding it easier (an old fire alarm service trick). If the test result suddenly rises, bingo!

There does come a point where re wiring a leg is the only sensible option - hopefully it won’t come to that!

Thank you bud. I’m loving this forum already being in communication with like minded individuals like yourself who can share knowledge.