RCD Tripping Fault

[securespark]

I went to help a colleague the other day on a fault-find.

The story was that when plugging in a load to an RF circuit, the RCD would trip after 8-10 minutes.

Without a load plugged in, the RCD would stay put. Also, testing with an Alphatek would trip the device.

By the time I got there, he'd megged the legs out and found a suspect: an outside socket. I unscrewed the cover and my colleague pulled away the front....

Water gushed out!!

 

[ColJack]

why 8-10 mins though?

 

[RF Lighting]

Wouldn't have been a problem had the installer drilled a drain hole

 

[ColJack]

I'm thinking electrolysis or Ionisation of the water due to a small leakage current of a few mA..?

 

[securespark]

Don't know why there was a delay. I'll sleep on that one, methinks!

 

[ColJack]

thought at first that it might be the water warming up a bit...
but like most things, the resistance of water increases with temperature..

 

[securespark]

Well, I've slept on it & I'm still none the wiser...

 

[ColJack]

I've googled it and I think it's the copper wire disolving into the water to electroplate the steel..
as the precess continues, more copper is disolved making the water more conductive untill enough current flowed to trip the RCD...

 

[Adam_151]

TNC-S ?

Mechanism must be something like what coljack proposed....low current flows at first, starts to ionise itself a better path and increases...

 

[Steve]

Least its watertight.

 

[securespark]

Yes!!

Not a drop escaped until we prised the socket from the mounting box...

 

[swidders]

Yes!!

Not a drop escaped until we prised the socket from the mounting box...

Maybe the cold weather has slowed the electricity down Trust you managed to order a new part using your new card. Oops

 

[securespark]

My diastolic BP is 90 & rising....

 

[swidders]

My diastolic BP is 90 & rising....

You may need private health care - just make sure you give them the long number on your ca......oops, double oops

 

[securespark]

Do the words "rub", "salt" & "wound" mean anything at all to you?