RCD tripping, could a surge protected extension lead be responsible?

[Pretty Mouth]

I had a fault finding job on Thursday, intermittent RCD tripping. 2 actually, there was a 30mA RCD upstream, and a 30mA RCBO protecting the problem socket circuit, and either one could trip.

I had limited time to work on it, but had eliminated everything obvious through testing, and was happy that the RCDs were working as they should be. The circuit only powered 3 points, and had few items plugged in - wifi router, printer, and a surge protected extension lead with a heater plugged into it.

The neon on the extension lead (indicating that the surge protection is working) was not on, so it must have been defective in that respect. However, the IR results while the extension lead was plugged into the circuit were typical for SP extension leads: >199Mohms at 250V and ~0.4Mohms at 500V (L+N to E).

Could the SP extension lead have been responsible for the tripping RCD(s), even though there was nothing unexpected about the IR results?

 

[James]

It’s entirely possible that the extension lead was faulty.
it is also possible that the surge protection was doing its job, filtering out surges and passing them to earth.
if surges are big enough, it is possible that too much energy was being sent to earth and this was tripping the rcd.

 

[ImpededLoop]

Yes, I had a neighbour who had intermittent RCD tripping. It was a surge protected extension lead that was causing it.

 

[Pretty Mouth]

It’s entirely possible that the extension lead was faulty.
it is also possible that the surge protection was doing its job, filtering out surges and passing them to earth.
if surges are big enough, it is possible that too much energy was being sent to earth and this was tripping the rcd.

Thanks James. Just to add to my previous post, the tripping happened perhaps 3 or 4 times while I was there. Usually with tripping of that frequency, the fault clearly shows its presence under IR test, but this time nothing. One test I didn't do was a 500V test with the extension lead unplugged, but as i mentioned, time was limited.

Yes, I had a neighbour who had intermittent RCD tripping. It was a surge protected extension lead that was causing it.

Thanks. I don't suppose you had the opportunity to IR test the offending extension lead did you?

 

[ImpededLoop]

After several visits I did IR test it (as I'd forgotten to unplug it!) and the test showed low resistance to cpc. Up until that point it had been a nuisance trip every few weeks.