Checking continuity of ring circuit

[Bob49]

Hi All,

Without going into the reasons why, I would like to confirm the continuity of one of the ring circuits in my house.

But I don't want to go messing with the consumer unit at all. So can I turn all power off and then take a socket cover off one of the sockets on the ring in question. Then using a multimeter (set to Ohms???) check the resistance between the pairs of live, neutral and earths?

If so what readings should I expect if the circuit is wired correctly?

Thanks,

Bob

 

[EFLImpudence]

can I turn all power off and then take a socket cover off one of the sockets on the ring in question. Then using a multimeter (set to Ohms???) check the resistance between the pairs of live, neutral and earths?

Yes, that's right. Set to Low Ohms.

If so what readings should I expect if the circuit is wired correctly?

The Line(live) and Neutral should be roughly the same and the CPC(earth wire) should be 1.67 times as much.

The actual values depend, of course, on how long the ring is.
2.5mm² (L & N) has a standard resistance of 7.32mΩ per meter @ 30°C.
1.5mm² (CPC) 7.32x2.5/1.5 = 12.2mΩ per meter.

Any values higher than expected would indicate poor/loose connections.

 

[Bob49]

Great thanks, and if there was a complete break in say the live, what would the reading be? Infinity?

 

[EFLImpudence]

Yes, open circuit.

 

[Bob49]

Great, thanks for replying.

 

[Bob49]

Yes, open circuit.

Just wondering do I need to unplug/switch off everything before testing continuity? I will turn off all power but do I need to unplug appliances as well? Washing machine for example. Will any residual charges in capacitors for example affect the reading?

Thanks

Bob

 

[EFLImpudence]

Switch off power.

No need to unplug anything for resistance test.

 

[Bob49]

Switch off power.

No need to unplug anything for resistance test.

Thanks

 

[Bob49]

Thanks

Hello again, sorry for another question! But can I just switch off the circuit I am testing or does it have to be the whole house?

Thanks for all your help BTW.

 

[EFLImpudence]

You can just switch off the power to the circuit but it is better to switch off the Main Switch.

You never know what faults or botch-ups might be present.

 

[Bob49]

Thanks