rcd spur keeps tripping, fused spur working fine

3 double plug sockets in the garage
With nothing plugged into to them, I assume? Nothing else (other than those 3 sockets)?

TTC has explained a logical way of "zeroing in" to the cause of the problem.

Kind Regards, John
 
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... or, as I have said, possibly an ineffective connection from a (correctly-connected) CPC to 'earth'.
If that's the case, then the answer to "is it safe keeping the standard fused spur which doesn't trip?" might be "It's not safe to use any of your electrical installation - house, garage, wherever."

skhudy - crack on and see if you can narrow the cause down to something in the wiring downstream of the FCU (which is probably where it is). If you can't, and if you have got an RCD which behaves as JW2 says some do, then you should get your entire installation checked, and thank your lucky stars that you did happen to buy an RCD which does that.

I take it your consumer unit has no RCD(s) in it?
 
If that's the case, then the answer to "is it safe keeping the standard fused spur which doesn't trip?" might be "It's not safe to use any of your electrical installation - house, garage, wherever."
Indeed, IF other parts of the installation also had CPCs which are not satisfactorily connected to earth. It could, of course, be that the problem only related to the CPC path to the one accessory - but the situation would certainly need to be investigated.
.... if you have got an RCD which behaves as JW2 says some do ...
You probably missed it during your absence, but a little while ago I investigated some RCD sockets. ....
No need to wait - my experiment 2 is now done. ... You're right about the Powerbreaker. I've just tried with a Powerbreaker H22. As you say, it won't reset without an earth connection. Furthermore, if one disconnects the earth whilst it is 'on', it immediately trips. It's therefore impossible to ascertain whether or not the test button is 'testing to earth' but, for what it's worth, when one does have an earth connection, the test button works as expected, and does not take out the upstream (also 30mA) RCD.
I have not tried with any RCD FCUs (I'm not sure that I have any to hand), but is seems far from impossible that if some RCD sockets behave as I describe above, that some RCD FCUs might behave similarly.

Kind Regards, John
 
Indeed.

Quite useful behaviour - a device which is supposed to improve safety in the way it does probably ought to detect a condition which would stop it working normally.
 
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Indeed. Quite useful behaviour - a device which is supposed to improve safety in the way it does probably ought to detect a condition which would stop it working normally.
Indeed so - and similarly, we speculate, the reason why (sometimes to our annoyance!) the test buttons on RCD sockets and FCUs seem to usually leak a current from L to the CPC (not 'across the RCD' as in standalone RCDs) - so again, the test button will also detect an inadequate CPC.

As we discussed in that other thread, it's not too obvious how they achieve ('simply') this 'earth-dependent' functionality - that will have to await an autopsy of one of these devices!

Kind Regards, John
 
just a standard multimeter. Is there any danger keeping the fused spur on? If so I may call a professional.
If you have a multi-meter you can at least start doing some of he basic dead tests, that may but may not help establish a problem.
I would test for continuity of all conductors and test for any dead shorts between them, continuity if done correctly will also prove polarity.
 
If you have a multi-meter you can at least start doing some of he basic dead tests, that may but may not help establish a problem. I would test for continuity of all conductors and test for any dead shorts between them, continuity if done correctly will also prove polarity.
That's true, but I think TTC's empirical approach would probably be quicker - i.e. remove all connections from load side of the FCU and then (assuming the RCD can be reset without any loads!) restore the connections one at a time until the culprit is found. That 'culprit' can then be further investigated.

Kind Regards, John
 
I think I asked the question about the RCD being loaded, in an earlier post. Not sure if the OP said it was or not. Time for a recap on topic's conversation.
 
One of the sockets is a usb socket, but no load on any plugs, nothing plugged into the usb. I have also tried a different working usb plug socket just in case one was faulty

Looks like the reply was not conclusive, with regards to anything actually being plugged in or not. I recall asking the OP to unplug everything, not just switch off at socket.
 
I think I asked the question about the RCD being loaded, in an earlier post. Not sure if the OP said it was or not. Time for a recap on topic's conversation.
You did, and there was no clear answer until I re-asked a variant of the question - and even then I had to ask further questions in an attempt to totally clarify.

However, I think the point is that you asked about loads (of which there were probably none), whereas I asked about, and TTC talked about, disconnecting "whatever was connected to" the load side of the FCU (probably just cables to other accessories).

Kind Regards, John
 
Yes I asked about loads, so to eliminate any appliances.
Thank you kindly for clarifying, where we are thus far. As I have not been keeping up with the posts/replies.
 

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