# At what point of the circuit do you test R1 R2?

## At what point of the circuit do you test R1 R2?

On a ring circuit, the live and earth are cross-connected at each end of the ring, and the R1+R2 measurement will generally be the same at each point on the ring, unless a fault is present. This also therefore helps identify points on a ring where a spur has been connected.

**How do you test insulation resistance on a ring main?**

To test a ring you must firstly measure the end to end resistance of L-L, N-N and E-E. You should then connect the incoming live with the outgoing neutral and measure the resistance at the furthest point in the circuit. Then also the reverse of the with the outgoing live to the incoming neutral.

### How do I know if my socket is on the Ring Main?

A general rule for a ring main is that if you only have two cables in the back of an existing socket then it is ok to spur. However, if you have a radial circuit with two cables coming in and out, this may be the last socket on that circuit and already has a spur.

**How do you test a phase sequence with a multimeter?**

You can set the Phase Rotation setting on your mutlimeter. Look for terminals labeled L1, L2 and L3 when inspecting the three-phase motor. The jacks that are labeled L1, L2, L3 should be connected to the power wires.

## How to test for R1 + R2?

On the test schedule (IEE model form) there is a column for r1, r2, and rn values, so its obviously a ring im testing. The next column along asks for either R1 + R2, or R2; R2 is long lead method which would give exactly the same value as r2.

**Should the (R1+R2) value be equal to R2 in a ring test?**

It certainly shouldn’t if done correctly! In fact it should be a quarter of the r2 value if there are no spurs. But given that the test for the (R1+R2) value is required as part of the ring final circuit continuity tests I see no merit in opting for R2 over (R1+R2) presuming that we are discussing initial verification here.

### What is the meaning of R1 in a circuit?

Try this explanation. r1 is your end-to-end resistance of the line conductor, say e.g 1 ohm, and now chop your ring in the centre. You now have two legs at 0.5 ohms each. If you rejoin the legs, you have, effectively, two lots of 0.5 ohms in parallel which equals 0.25 ohms.

**How do you calculate R1 and R2 resistance?**

r1 is your end-to-end resistance of the line conductor, say e.g 1 ohm, and now chop your ring in the centre. You now have two legs at 0.5 ohms each. If you rejoin the legs, you have, effectively, two lots of 0.5 ohms in parallel which equals 0.25 ohms. Now do the same for r2.