Checking Continuity

[dk1uk]

Hi - last year I replaced all light switches and sockets in my house with metal ones.

I made sure that all the earth cables were connected etc.

However, I didn't perform continuity checks on the earth wires...

In total, there are probably about 60 sockets/switches. If I have to unscrew them all to check the continuity then I will. But I wondered if it would be acceptable to touch the multimeter prong on the socket/switch faceplate rathet than open every socket/switch. If not, then fine, but I wanted to check before writing off my weekend on this job.

Many thanks

 

[flyingsparks]

Of course going to the front of the plate is fine. Are you going to use a 'wondering lead' from your MET to take the measurements? Have you any reason to think that some may not be connected?

 

[dk1uk]

Perfect - thank you.

Yes, I was going to use the lead from the point next to the consumer unit where the earth cables are - if that's called the MET?

My only concern is that some of the earths weren't connected in one of the rooms in the house when I did a continuity test last year. That room is part of an extension. I have no reason to suspect that anything is wrong in the original house but for the sake of an hour's work I'll sleep easier!

Thanks

 

[JohnW2]

Of course going to the front of the plate is fine. Are you going to use a 'wondering lead' from your MET to take the measurements? Have you any reason to think that some may not be connected?

Do all metal sockets automatically have the earth of the socket factory-connected to the faceplate, or do any have a separate earth terminal for the faceplate, without any built-in connection to the earth of the socket?

Also, if any of the accessories are lacquered brass (or lacquered anything else!), does the lacquer always conduct?

Kind Regards, John

 

[dk1uk]

Sorry I meant to ask - presumably it's OK to leave the power on if I'm only going to the faceplate - it won't affect the validity of my test?

 

[bernardgreen]

Sorry I meant to ask - presumably it's OK to leave the power on if I'm only going to the faceplate - it won't affect the validity of my test?

If you are using a multimeter then the continuity results will be affected by currents induced in the earth wires by the AC current flowing in adjacent wires in the cables. How much affect depend on the type of meter and the lengths of cable involved.

But in most domestic installs the average multimeter results will be sufficient to prove or dis-prove continuity. Any doubts do the tests with the power of.

Take care and before testing for continuity do a test for AC voltage between wander lead and the face plate, the plate could be live and if you touch it while also holding the earthed wander lead you could get a serious shock

 

[dk1uk]

Thanks - so I do an AC test on the plate whilst the wander lead is connected to the MET?

If the plate is live, wouldn't I expect a shock even if I'm not holding the wander lead (if I touch the plate with my hand). I use most of the switches/sockets regularly as so far so good, but hence why I want to check the earths so that I'm not relying on luck

 

[Astra99]

My inclination would be to use a cheap 3-neon socket tester first. Whether or not all three neons illuminate, indicating earth present or not, or other (potential) fault, kill the circuit and do a "prod" with the multimeter.

These cheap plug-in socket testers are ideal for a quick and dirty check, but are best nor relied upon for circuit integrity. (There are some expensive plug-in testers which do more, but expensive is the operative word!)

Caution. No lights on the socket tester could mean the live cable has fallen out the connection to the socket and is still live! Disturbing the socket and it could go fizz-bang-smokey!

 

[bernardgreen]

You only get a shock if you make contact with two items that are at different potentials. So you can touch a live wire provided no part of your body is touching anything else that is conductive to a different voltage.

Do not try this, you may get it wrong

That is why birds can perch on 11 kV over head cables.

With good quality bone dry carpets a live metal front plate can go un-noticed until some touches it while also touching something earthed.

 

[dk1uk]

Thanks again. How would I use my multimeter to first check that the faceplate isn't live?

Thanks.

 

[JohnW2]

Thanks again. How would I use my multimeter to first check that the faceplate isn't live?

With your meter set to a high (400V or 600V) AC voltage range, connect one of its probes to you wandering lead connected to the MET, and touch the other onto the faceplate.

Kind Regards, John

 

[ban-all-sheds]

Are you going to use a 'wondering lead' from your MET to take the measurements?

I wandered that too.

 

[OwainDIYer]

In total, there are probably about 60 sockets/switches. If I have to unscrew them all to check the continuity then I will.

Use a test plug adapter eg

http://www.testermans.co.uk/-kewtech-kewcheck-r2-socket-test-adaptor

If you unscrew the socket it may test OK but then the earth wire pop out as you screw the socket back ...

 

[Taylortwocities]

That's not going to help him testing the light switches…

R2 test to front panel or screw of each accessory rom the MET will be fine.
I would do a continuity test on the loop of ring final circuits first.