RCD tripped, why?

[CaptainBob]

My boat has a domestic mains distribution board (if that's the right name for it) which has a built in global RCD, and trip switches for each circuit.

I wanted to remove the mains wiring from my calorifier heating element.

I know I should have disconnected the mains completely, but instead I just turned off the trip switch dedicated to the calorifier heater.

I unscrewed the wires and pulled them out through the calorifier's metal housing, and some or all of them contacted each other... and tripped the main distbution panel RCD _and_ the RCD at the yard's supply point.

Is that correct? Should that have happened? I'd turned off the power to the calorifier at the panel, and it was definitely OFF.

My concern is that the installer has perhaps put the neutral side through the panel, not the live, so switching things off will work, but LIVE is still connected to each item. I'll test this next time I'm aboard in a few weeks.

But would it have tripped even if LIVE was correctly disconnected and the neutral and earth wires (or some other combo) came into contact with each other?

I did have other things (mains things) ON in the boat at the time.

TY!

 

[sailorman]

the RCD will prol be a 30ma device so very sensitve to any earth leakage. the earth wires all go to the same connector in the consumer unit so when you made contact it worked as it should. only the + is wired via the mcb (trip)



experts will be along soon

 

[MoodySabre]

Isn't an RCD an earth leakage device? Touching earth and neutral will trip it. You had switched off the live but earth and neutral were still connected.

Out typed by SM

 

[philip_stevens]

This is a problem in the UK, in that we only have a single pole circuit breakers in the consumer units. I say a problem, as I am an electrician on ships, and the supply is usually two phase - on 240vac.

I have to ensure that all switches and sockets use double pole switching to ensure both L and N are isolated.

This is the reason you will find DP switching on some continental portable equipment.

I had to work on a small ship that came from France, and had double pole cct brkrs in the consumer unit. These were the same width and size as UK single pole modules, and managed to get new modules of the same size from a local wholesaler.

I have a small generator on our boat, and when in use, I do not get any earth indication on the phase checking plug - only that the supply is the correct way around.

The calorifier on our boat has a DP/neon switch to its supply.

 

[PeterBoater]

I have a small generator on our boat, and when in use, I do not get any earth indication on the phase checking plug - only that the supply is the correct way around.

Philip
I recently connected a portable 2.2 kVA generator to the boat and the reverse polarity warning light on the boat's AC panel illuminated, although the boat's RCD held. When I bought the generator (for domestic use), I found that putting an 13A plug RCD in the circuit would immediately trip the RCD. Is the generator wired up incorrectly? Thanks for any advice.

 

[VicS]

My boat has a domestic mains distribution board (if that's the right name for it) which has a built in global RCD, and trip switches for each circuit.

I wanted to remove the mains wiring from my calorifier heating element.

I know I should have disconnected the mains completely, but instead I just turned off the trip switch dedicated to the calorifier heater.

I unscrewed the wires and pulled them out through the calorifier's metal housing, and some or all of them contacted each other... and tripped the main distbution panel RCD _and_ the RCD at the yard's supply point.

Is that correct? Should that have happened? I'd turned off the power to the calorifier at the panel, and it was definitely OFF.

My concern is that the installer has perhaps put the neutral side through the panel, not the live, so switching things off will work, but LIVE is still connected to each item. I'll test this next time I'm aboard in a few weeks.

But would it have tripped even if LIVE was correctly disconnected and the neutral and earth wires (or some other combo) came into contact with each other?

I did have other things (mains things) ON in the boat at the time.

TY!

As already confirmed shorting neutral and earth together will trip an RCD. There is likely to be a very small voltage between them and sufficient current can easily flow to trip an RCD.

Last time I did it, deliberately, it also wrecked the RCD ! I suggest therefore that you test the RCD.

 

[CaptainBob]

Thanks everyone. Will check it Vic.

 

[VicMallows]

I unscrewed the wires and pulled them out through the calorifier's metal housing, and some or all of them contacted each other... and tripped the main distbution panel RCD _and_ the RCD at the yard's supply point.

Completely normal, and working as it should do. When working with just the breaker/fuse off, I routinely make a point of insulating the neutral. Even then, I try to remember to turn off computers etc first in case of any accidental trips.