ring testing

[beaver74]

I have come across this many times the quality of sockets now seem poor as relation to contacts.if high or all over the shop i find that connecting to terminals direct sorts out a proper reading but it is a pain in the but

 

[WayneL]

Hi Soulman,

I'm not sure if the 'Mains Test Lead' (if that's what you are referring to) is supposed to be used for continuity - this could be your problem.

How does it connect to your tester?

 

[pevvers]

I use my Megger to do dead testing on sockets, as all you're doing is checking continuity, whether this be with a 13A plug top or a probe set, it's all the same!

I think it's actually better that way, as you'll get the reading you would actually get from the socket...

 

[soulman]

it's the mains adaptor. connects via terminal that you put probes in. spoke to fluke direct they told me to put the neutral lead into the earth to do the r1+rn crossover test

 

[soulman]

I use my Megger to do dead testing on sockets, as all you're doing is checking continuity, whether this be with a 13A plug top or a probe set, it's all the same!

I think it's actually better that way, as you'll get the reading you would actually get from the socket...

do you still get incorrect readings from time to time or not
cheers

 

[pevvers]

Yes, but this is most probably due to loose contacts inside the socket causing the extra resistance. It's only a 200mA current that's passed through it, which is why it shows.

As I said at the start of the thread, I find that sometimes different sides of the socket will give you different readings, sometimes quite a significant amount, which I can only put down to the quality of the construction of the socket.

If you are going to use the socket and see plug top tester, then this is no different to using the mains lead and in fact you may be putting more resistance into the circuit from the contacts between the leads and the socket interface...

 

[WayneL]

it's the mains adaptor. connects via terminal that you put probes in. spoke to fluke direct they told me to put the neutral lead into the earth to do the r1+rn crossover test

That's why I was asking.

So yours has the three coloured plugs on the end and you connect whichever two you require into the 'red' and 'green' on the meter?

That's ok then - you see, Megger also do a mains lead with one three way plug on it (plugs into a special socket on the meter) - I don't think this one is meant for continuity testing.


I have two more questions for you, Soulman:

Who on earth said it was okay to cross-connect at the socket?

And why would you want to?

 

[pevvers]

That's ok then - you see, Megger also do a mains lead with one three way plug on it (plugs into a special socket on the meter) - I don't think this one is meant for continuity testing.

The 13A lead for the Megger works absolutely fine for continuity testing, if it's good enough for loop testing then why wouldn't it be for continuity?!!? It's measuring exactly the same conductors, but when measuring loop it's all the way back to the tranny.

Who on earth said it was okay to cross-connect at the socket?

I have a feeling that this is a joke from earlier on in the thread, and can't be bothered to trawl through...

But there's nothing wrong with cross connecting at a socket instead of inside the board, sometimes it's much easier especially if you have a packed out board.

 

[WayneL]

The 13A lead for the Megger works absolutely fine for continuity testing, if it's good enough for loop testing then why wouldn't it be for continuity?!!? It's measuring exactly the same conductors, but when measuring loop it's all the way back to the tranny.

The Megger lead with the three seperate, coloured plugs on the end will work fine but I don't see how the 'all-in-one' plug will work on continuity.

How does the meter distinguish between which test you are doing (R1 + Rn or R1 +R2)?

On Zs testing it knows to test between L & E, but it won't know on continuity of RFC.

But there's nothing wrong with cross connecting at a socket instead of inside the board, sometimes it's much easier especially if you have a packed out board.

Sometimes.

I've got a feeling that the OP might be cross-connecting at the socket so that he only has to isolate the RFC at the MCB, instead of the whole installation.

If this was the case and he was working on a TN-C-S system, the Neutrals and CPCs of the ring final are basically connected together.

If when testing your R1 + R2, you wouldn't know if you had a neutral/earth swap at the socket, because you'ld get a reading either way.

And lets not pretend that people never just isolate the circuit that they are working on

Then, even if you isolate the whole of the installation correctly at the main switch (both poles), you could still have the same problem (as above) if there were a N/E fault on another circuit that you didn't know about.

That's probably why cross-connecting at the socket isn't a given method in any of the books - or if it is, I haven't come across it, and I certainly wouldn't do it.

 

[pevvers]

The Megger lead with the three seperate, coloured plugs on the end will work fine but I don't see how the 'all-in-one' plug will work on continuity.

Ah yes, I was just talking about the R1+R2 readings, not the R1+Rn. Which is true, you would only be able to test the former with the 13A mains lead.

I've got a feeling that the OP might be cross-connecting at the socket so that he only has to isolate the RFC at the MCB, instead of the whole installation.

If this was the case and he was working on a TN-C-S system, the Neutrals and CPCs of the ring final are basically connected together.

If when testing your R1 + R2, you wouldn't know if you had a neutral/earth swap at the socket, because you'ld get a reading either way.

And lets not pretend that people never just isolate the circuit that they are working on

Then, even if you isolate the whole of the installation correctly at the main switch (both poles), you could still have the same problem (as above) if there were a N/E fault on another circuit that you didn't know about.

That's probably why cross-connecting at the socket isn't a given method in any of the books - or if it is, I haven't come across it, and I certainly wouldn't do it.

A very good point indeed, I was taking it as he had done a whole test on the board that would have included neutral-CPC IR tests, and also had the main switch open...

Never good to assume eh!

 

[soulman]

cheers wayneL
a working spark told me it would be o.k to practice my ring circuit testing at a socket instead of the consumer, So i could get some readings as i couldnt get any on my test rig. the earthing arrangement is tncs and i did just isolate that circuit.