Testing Consumer Unit, Now Switch Keeps Tripping!

[Rsian]

Hi all,

I wonder if someone can help?

*Apologies for my poor upcoming terminology*

I have a shed at the end of my garden which I need to dismantle which has power going to it.

The previous owner wired up the garden and didn't label things all that clearly, so I have been testing trip switches to make sure I know what is powering what.

Below is the consumer unit in a brick building attached to the house.

The circled switch in the consumer unit below connects to the triple switch above it.

By flicking the switches, I have figured that the left switch connects to a small consumer unit in the shed at the end of the garden, the right switch connects to the pond pump.

Having checked and double-checked everything, the main consumer unit trip switch leading to the triple one will now not stay on - it won't remain in the 'on' position at all.
I am not sure if I have created a fault, or if the switch is faulty.
I have switched all switches to off (shed, pump and consumer unit in end shed), and still it won't stay on.
The switch immediately to the left of this one in the main consumer unit, when tripped, has definite movement on the small test button above it, the test button on the one that is now not working doesn't appear as obvious, but I can't believe I have damaged the test button from what I have been doing.

Any advice please - the pond pump is currently not working now!

 

[333rocky333]

It looks like an, rcd, have you checked everything connected to it is off or unplugged, if the truth is that you only turned it off and not tampered with anything, then it may just be a case of it dont like being turned on under load.
does it switch on ok with the switch above in the off position
That consumer unit is obsolete now so you wont get a new rcd to fit it if you wanted to

 

[Rsian]

Hi 333, thanks for the reply.

So...I have switched off the consumer unit in the garden shed, and turned off the water pump switch.
I then turn off the main house consumer unit (pictured above), and switch the tripping switch to the 'on' position - it stays on.
I then turn on the house consumer unit, and the tripping switch trips to 'off' - under no load.

Advice?

 

[333rocky333]

have you tried turning it on with the house consumer unit already ON

whats in the box marked shed and pump above the house consumer unit,
if so turn them off inside.

So, house CU on, then circuit rcd, then turn on whats in the box one at a time

 

[flameport]

Test button could be stuck in, tapping the circuit breaker with a screwdriver handle may release it.

 

[Rsian]

Hi.

I have done the following:

House CU 'on', Shed/Pump Box all 'off'. Tripping RCD will not switch to 'on'.
House CU 'off', Shed/Pump Box all 'off'. Tripping RCD will stay in the 'on' position...turn House CU 'on' will trip the RCD.

 

[Rsian]

Test button could be stuck in, tapping the circuit breaker with a screwdriver handle may release it.

When I turn the House CU to 'off', the tripping one will remain in the 'on', position (under no load), until I switch the House CU to 'on', and it trips.

Basically everything was, and has been, working perfectly until I decided this afternoon to double-check what RCD is connected to what source. Since then, it just won't come back on again.

All I have done is turn off the shed CU and turn the RCD in the House CU on an off a couple of times to make sure I was definitely killing the power to the shed (which I was).

 

[333rocky333]

Can you post a closer pic of the smaller box above the CU
Do you feel competant to take the cover of the smaller box and get a pic of that
Turning off the main cu cuts the power, the rcd needs power to trip, so the rcd will reset ok, that indicates the problem is AFTER the rcd,or inside the rcd, so the circuits need breaking down within the smaller box to locate the cause

 

[Rsian]

Pics attached.

As said, haven't touched anything, other than to trip these switches, the RCD on the House CU leading to this box and the CU in the shed.

 

[Iggifer]

Damn, apparently this didn't post about an hour ago:

The little 3-way wylex that has the shed and pond pump in it - what does the middle MCB control? The fault could be on this circuit and you're missing it by only assuming it's the shed/pump.

It's a neutral-earth fault if it won't reset with the MCBs off.

 

[Rsian]

Damn, apparently this didn't post about an hour ago:

The little 3-way wylex that has the shed and pond pump in it - what does the middle MCB control? The fault could be on this circuit and you're missing it by only assuming it's the shed/pump.

It's a neutral-earth fault if it won't reset with the MCBs off.

There is a label on the House CU tripping RCD which says 'Shed, Greenhouse, Pond', so I assume the middle one used to control the greenhouse.

There used to be a greenhouse before we moved in, but the owners dismantled it and sold it. The previous owner was an electrician for the council, so I assume he did what he had to do correctly when he dismantled the greenhouse and sorted out whatever wiring he needed to sort out (this was about four years ago).

 

[333rocky333]

so theres a shed and a pump, whats the 3rd trip, is that another shed.

Rcds struggle to reset under load or a fault.
Are you 100% sure everythings disconnected at all 3 of them locations.

if so then its a possible neutral problem, that will be harder to locate as that small box looks quite compact to work in
the 3 mcbs only break the live conducters so although there off. the return neutral black wires are still connected to the rcd possibly stopping it resetting.

Does the water pump unplug, you say its switched off, but unless the switch is double pole, then it doesnt switch the neutral, if the pumps blown possibly by just stopping and restarting it, then that could stop the rcd resetting.

 

[Iggifer]

Re: the greenhouse, he has left the cable connected in the consumer unit, so it must go somewhere.

It's worth having a poke around in the morning where the greenhouse used to be (if you know) there could well be a box that the cable terminates into that's got wet, or as Rocky says, the pond pump may have gone U/S

 

[securespark]

I was about to suggest an NE fault.

Power down the 3 mcb box and fish out the neutral terminal in the top.

Disconnect the outgoing neutrals from the incoming, then reconnect them one by one. You should find one that trips.

 

[Iggifer]

Power down the 3 mcb box and fish out the neutral terminal in the top.

Sage advice of course, but, he can't power it up anyway currently!

Just to elaborate on that last bit a touch - once you've disconnected all the neutrals - it should be clear which is the supply neutral, leave that in. Reconnect one, and attempt to power up. If it allows you to reset the RCBO, power down again. Remove that neutral, and move to the next one. You should find that one (or more) will not allow you to reset the RCBO. This is your faulty circuit and will require more investigation.

TBH my money is on the pond pump, or the unknown end of cable.