Martindale (Ring Main) tester

[Cicero]

This tester (Martindale) and other similar testers are described as 'Ring Main' testers. They're supposed to provide a basic safety test on a ring yet mine also appears to work on the 13 amp socket on my cooker unit which isn't on a ring.

Two questions:

1. Is the tester showing a correct result for the 13 amp socket on the cooker radial circuit or is it giving a spurious result?

1. If it's giving a correct result for the socket on the cooker radial circuit could it also be used safely and reliably on a lighting circuit by installing a *temporary* socket in a lighting circuit?

Cicero

[Toby]

If you are talking about one of these

it really just checks the Live is in the corret place, it cant tell if the Neutral and earth is reversed.

Toby...

[Tim S]

Toby coughed up some electrons that declared:

Indirect reply to the OP:

Ring or radial: it doesn't make any difference to those testers.

There's a fancy Martindale that does claim to guage L-E impedance. But it's only an indicator (4 or 5 LEDs IIRC, so a very coarse reading). As Toby says, there isn't a tester on Earth in that format that can tell N-E reversal.

It would have to be said though, that those test plugs are really only good for basic polarity checks (N-E reversal case noted). For actually proving a circuit you really need a proper tester unfortunately. To get any idea if the earth (CPC) is any good, you need to measure it's potential to actually carry a sensible amount of current, rather than the tiny test current socket testers employ.

Cheers

Tim

[Harry Bloomfield]

Cicero has brought this to us :

They are a very rough and ready test of the polarity of a socket, rather than a ring main. They would not be able to distinguish between correctly connected N & E and these two crossed over.

Even allowing for the above, they only test there is an earth of some sort, not the quality or safety of that earth.

[Dave Plowman (News)]

They do a rather more sophisticated one that does a rudimentary earth impedance test. Not cheap, though.

[Cicero]

I was aware that this tester won't detect a Neutral / Earth reversal because that is printed on the face of the actual tester. In view of the limited capabilities I don't think I'll be spending £42 on the advanced version, despite the claims made for it.

I'm a bit surprised that TLC describe it as a 'Ring main tester' when it appears to offer no actual test that a circuit is in fact a ring.

Cic.

[Dave Plowman (News)]

I'd say it's because to most 13 amp means ring. And you'd need a *very* sophisticated tester to detect there was a break on a functioning ring.

[Cicero]

========================================= That seems a reasonable and common sense explanation.

There is a testing method (I think) described in 16th Edition Wiring regulations - Explained and illustrated- Brian Scaddan. I'll need to read it again to be sure, when I've got time.

Cic.

[Harry Bloomfield]

Cicero used his keyboard to write :

That is a matter of disconnecting the two wires at the MCB and measuring the resistance between each pair (L to L, N to N and E to E). Obviously infinity means there is a break in the ring.