R1 r2, ring main.

[john1980..h]

Hello there,

i'm a bit new to this this is my first question on any forum, let alone the electricians forum.

When performing an r1 r2 on a ring main, and you can't identify one leg from the other, ie singles or the db is really congested.
How can you ensure you are connecting the correct earth to the live of the other leg, and vice versa.
Without having to pull the circuit apart.
Will you be able to tell by differing measurements.
Any help will be greatly appreciated.
John.

 

[telectrix]

if its a ring, you will get end to end continuity L/L, N/N, E/E on the correct ends. always mark cables when installinjg, makes life a lot easier

 

[BillyBoBob]

Stage 1 = end to end test. Results will be r1, rn,r2
Stage 2 = Interconnect Line and Neutral. Test at all points. Results should be (r1+rn)/4 at each point, + or - 0.05ohms of your expected result.
Stage 3 = Interconnect Line and c.p.c. Test at all points. Results should be (r1+r2)/4 at each point, + or - 0.05ohms of your expected result.

If you see your readings rise slowly to the mid-point of the ring then drop again as you return to the DB then you've interconnected incorrectly.
If it's done right, you should recieve the same reading on all points of the ring as when they are interconnected correctly there is no mid-point of the ring.

Your on-site guide will give you a better explanation.

 

[scotsparky]

just a tip if you are really stuck identify the circuit and test it all from a socket with cables still connected at D.b readings should be the same.

 

[telectrix]

some time ago, i knocked up an alarm internal siren wired into a pair of 4mm plugs (to fit breakout box). shove 12v from the CU down the correct L/N and you will hear it from anywhere in the building. on a ring you'l get 2 pairs that work