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)
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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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I seem to remember at one of the training centres I visited once, they had an extension lead with some kind of resistor set up so an RCD test on anything connected to that extension lead would not trip the one back at the board.
Helpfully, I can't remember what it was though.
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I could connect the neutral to earth in an extension lead, and test a plug in device, but since it would not power up, and I broke it apart to see how it worked, that is now rather pointless.
The shutters rotate, and it is clear it opens a contact as the plug is inserted, but also the relay is open, and seems to have some sort of system whereas when the plug is inserted, it manually works the relay but not before inserted or after, just during it being inserted. And only as inserted, not when removed.
Not sure if I would trust it? And the main reason for using a plug in RCD was the no volt release. So if the appliance has been switched on when we have a power cut, it will not restart when power returns.
But it simply would not fit in my outside sockets, the socket lid hinges up, and would not allow it to be plugged in, even with the lid open. This
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Its a belt and braces approach having 2 same type rcds in series
In electrical terms though it's a bodge .
Operate the test button regularly on the rcd and have it tested professionally annually.
In electrical terms though it's a bodge .
Operate the test button regularly on the rcd and have it tested professionally annually.
Not always - but dand messed with all of the tiiue account must be considered of it tripping one and/both RCDs on fault and the inconvience of not knowing that!
Reminds me of something a good while back, and an Electrician and his handy pal, the Electrician rang to consult with his pal about the next job they were going on.
His Wife answered phone "He can not come to the phone at the moment, the kids have been playing about with the TV and be is laid on his back under the TV with the back off trying to adjust the tuning and he is screaming at the kids!"
"Oh, nobody in this are can get TV - the local transmitter has gone down!"
LOL
He didget some stick at the wholesalers a fewdays later
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That's the bodge in electrical terms
Either or both can trip and not knowing
Doesn't mean it doesn't provide added security but you won't find it in any electrical design that im aware of
Yet!
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