Plug in RCD- rapid clicking

[opps]

Hi all

My dust extractor has a wired in RCD plug.

Similar to https://www.toolstation.com/rcd-plug/p99372

Yesterday I went to plug in the dust extractor at my mate's house, the RCD just kept making rapid clicking noises. In the end, I used my circular saw (pugged in to the same wall socket) without dust extraction.

After, my friend flicked the MCB off and on. We then plugged the RCD plug in, and it was absolutely fine.

Does anyone know why it would do that?

Thanks in advance.

Edit- for the record I don't know if the ring has RCD protection. We tried other sockets on the same ring.

 

[SUNRAY]

The plug you linked to needs to be reset each time it's plugged in.

If you are you saying the RCD stays on when unplugged I'd suggest it's faulty.

 

[opps]

The plug you linked to needs to be reset each time it's plugged in.

If you are you saying the RCD stays on when unplugged I'd suggest it's faulty.

My RCD plug defaults to on when plugged in. When I purchased it I had a choice of default on, or default off, when plugging it in to the wall socket.

The plug doesn't seem to be faulty. That one occasion was the only time in 10 years that it acted that way. I suspect that there is something wrong with his ring but can't think what, or why it would be intermittent.

I am guessing that an RCD works in "both" directions- ie both up and downstream.

 

[opps]

I swung by his house this morning. I had to pick up some tools.

I had my Martindale EZ150 socket tester with me.

The first socket showed three green lights (meaning wiring ok and voltage OK) and green on the 0 ohms loop test. The second socket that I tested showed the same result. The third socket however showed a red light in the middle- which the tester says means "open earth, more than 500 ohms".

I went back to the first socket, still ok, then back to the last socket which was now showing all ok. I plugged my RCD plug in and it started clicking again.

I appreciate that the socket tester is a rather blunt tool but why would it have shown "open earth", and all OK later?

It seems unlikely that both my RCD plug and socket tester have both developed faults in the same house over a short period.

BTW The tester does say that it cannot detect neutral and earth reversals.

 

[flameport]

Loose connection at the socket, or some internal failure meaning the earth is not always connected.

The clicking is probably the relay in the RCD plug energising then immediately disconnecting when the lack of earth is detected.

The socket needs to be connected properly or replaced.

 

[opps]

Loose connection at the socket, or some internal failure meaning the earth is not always connected.

The clicking is probably the relay in the RCD plug energising then immediately disconnecting when the lack of earth is detected.

The socket needs to be connected properly or replaced.

Thanks.

Given what you say, I am wondering if the earth is only connected on one side of the ring and that the socket that showed open earth is the one with a loose earth (and a earth that doesn't go back to the consumer unit, ie. has a break somewhere). It is one of those sockets with usb sockets. I might recommend that he temporarily replaces it with a basic plastic socket, and then test the socket with either of the earths removed.

I have since discovered that the consumer unit is a split load with RCD protection on both the lights and rings. The RCD doesn't end up tripping, is it happy so long as it doesn't see a leak to earth?

 

[333rocky333]

The consumer unit Rcd just monitors that the current out via the Live is same as what comes back to the N, there is no physical connection to earth, whereas your socket does have earth connection and more complex, it appears quite common for the sockets to work erratic or go off if that earth is iffy

 

[opps]

The consumer unit Rcd just monitors that the current out via the Live is same as what comes back to the N, there is no physical connection to earth, whereas your socket does have earth connection and more complex, it appears quite common for the sockets to work erratic or go off if that earth is iffy

Thanks.

And you have just reminded me that another friend noticed that his customer's sockets had a earth fault because the antistatic hose on his Festool dust extractor was covered in dust when sawing.