I`ve just edited post number #14 - hopefully I`ve finally cleared it up!
Protector-Plug Flymo
- Thread starter ericmark
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Yes, the earth pin just goes straight through, there is no connection to the circuit board. But the tester still connects to earth to do the testing, there is no test button on the plug in RCD.
Eric, just to clarify, with the lead I mentioned the E from the circuit being utilised fro the installtion itself is not connected to anything in the lead at all.
A "Fake Earth" is employed from the household N in the socket.
The RCD under test sees an N and an L and another N at its earth position (a two core (N & L) could be used if the test meter did not require something of Earthy polarity to appear on its Earth terminal, so the equipment under test works and will time the RCD trip time but and installation RCDs just see a N L balance so do not trip.
You have tricked your test meter into believing an E is present yet it is not present.
It is a naughty trick but if all you ever use it for is to trick your test meter into a false belief then no harm done!
A "Fake Earth" is employed from the household N in the socket.
The RCD under test sees an N and an L and another N at its earth position (a two core (N & L) could be used if the test meter did not require something of Earthy polarity to appear on its Earth terminal, so the equipment under test works and will time the RCD trip time but and installation RCDs just see a N L balance so do not trip.
You have tricked your test meter into believing an E is present yet it is not present.
It is a naughty trick but if all you ever use it for is to trick your test meter into a false belief then no harm done!
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Things used in the garden will do that.
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Well one RCD might be good enough if functioning correctly but 2 or 3 or 4 or 100 inseries might, on occaision, make that difference at that one special time, I long remember installations with no RCD at all and an MCB or even a rewireable fuse (always check the correct fusewire present and wired properly) and it never caused any concern.
I use that lead to check various RCDs on my test meter (RCCB, RCBO, RCD adaptor or socket oulet etc etc before putting them into service to give me a rough idea how they might work when finished - off course a lead or lag on the circuit or even leakage from any cause might alter that figure but if you have a faulty one (very rare unless it`s secondhand) then it gives some reassurance.
I use that lead to check various RCDs on my test meter (RCCB, RCBO, RCD adaptor or socket oulet etc etc before putting them into service to give me a rough idea how they might work when finished - off course a lead or lag on the circuit or even leakage from any cause might alter that figure but if you have a faulty one (very rare unless it`s secondhand) then it gives some reassurance.
Personally I would not make this lead, instead I would make two leads. One lead from a 13A plug to 4mm shrouded connectors and one from 4mm shrouded connectors to a 13A socket.
Why? because if the lead you propose gets misplaced, then someone (including your future self) may mistake it for a regular extension lead. Then they may plug it into a travel adapter, or a circuit with a broken neutral or whatever and give themselves a shock.
Whereas a lead with 4mm shrouded connectors is far more obviously a piece of test equipment.
As a bonus the leads with 4mm connectors can be used for other things, like measuring the voltage at a socket, or performing an insulation resistance test on an appliance or making current measurements.
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Or use one of these:
Wired correctly to its plug there's no danger of misuse.
The test socket would have a flex with no plug, so no danger of inadvertent misuse.
That flex could have its N & E cores connected to the N in the test block only as and when required.
The test block is actually designed for safely making temporary connections to "the mains", unlike 4mm plugs & sockets.
Both of those suggestions indeed have merit I agree.
The lead I mentioned is kept secure and has sufficient labels firmly attached. As far as possible it will only be used by me (or one or two of my colleagues in my presence in at least the same way as I use the rest of my test gear)
.
My intention of mentioning it on here is solely for those competant enough to use one safely.
The lead I mentioned is kept secure and has sufficient labels firmly attached. As far as possible it will only be used by me (or one or two of my colleagues in my presence in at least the same way as I use the rest of my test gear)
.
My intention of mentioning it on here is solely for those competant enough to use one safely.
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