RCBO question

Mar 19, 2019 Last reply: 7 years ago 13 Replies

Not my finest moment, but I was carrying out a minor electrical job. As I was wiping up the dust with a damp cloth, I came into contact with a live part of a different circuit that I did not know about.



My question is why the RCBO did not trip. I only received a slight tingle but I thought RCDs and RCBOs were supposed to detect any leakage to earth.


They need to see 30mA to trip, given Clive's reaction to 13mA

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your "slight tingle" was presumably lower than that?

A slight tingle is very probably much less than 30mA, so a 30mA RCD won't trip - 1mA is often taken to be the smallest you can feel.

30mA would be quite painful, though with an RCD not for long, and you're far more likely to injure yourself when you fall off the ladder or drop the circular saw on your foot than from the shock itself.

Cheers

Nothing like that. Thanks, that explains it.

Not any, more than a specified current, otherwise they would trip with the mains filters most modern electronic devices have.

Point of order Andy, its customary to say "Spoiler alert", I don't check for new BC videos until just before bedtime ;-)

Worth mentioning that the 30mA RCD will not limit the shock current at all - all it does is limit the duration of the shock if the shock current is 30mA or more.

Yes, I should have made that clear, I'd make a poor teacher. (Which is just as well because I'd rather chew my own arm off.)

Cheers

It did trip and you died; you then went to an alternative universe where electricity doesn't harm you.

Bill

If a slight tinge tripped everything it would be a nightmare. I get slight tingles off of most supposedly double insulated devices when I plug in a cable to an earthed bit of kit. Brian

Andy probably did you a favour then. You might not have wanted to watch that one just before trying to go to sleep.

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