Power shower tripping earth leakage switch

[DougieB]

I have owned my house for about 4 year. In this time, the earth leakage switch has tripped from time to time, enough to be an annoyance but infrequent enough to put off.

Recently, while undergoing a bathroom overhaul, I changed the power shower. Thinking was that I'd use the same wiring and have a look at the later (next job). Now, having traced the wiring, it goes shower --> plug with 3A fuse --> fused switch with 13A fuse --> 30mA RCD powering all plug sockets in house.

When I power up (not switch on) the shower via the 13A fused switch, the earth leakage switch will trip maybe 80% of the time. If I leave it powered on, I get maybe 1 trip per 24 hours. Pretty much rock solid if I leave if off. We got maybe 1 trip / month with the old shower.

I've double checked the shower wiring and all should be OK. Question is:

- What is the minimum I need to do to make this work safely? Have the shower wired to a separate 30A / 45A RCD (is 45A unsafe)?

- What should I do ideally? Have separate RCDs for upstairs and downstairs plus one extra for the shower?

- I understand you used to be able to contact the electricity board (!) for a free quote and advice? Does anything like that exist these days? I'm with Scottish Power.

- I assume we're not in imminent danger whilst we shower?

Thanks,

Dougie

 

[securespark]

Leaving aside the odd arrangement for the moment, your socket does not need to be on to cause an RCD trip because (if it is SP) the neutral is not disconnected from the load.

It sounds like you have an earth fault on your shower.

 

[lookinn]

Had the same kind of prob. Spray inside of switch with WD40. With power off of course. Worth a try. Only needs a bit of damp to trip it.

 

[JohnD]

This is a power shower, i.e. an electric motor driving a pump? look for traces of water leakage affecting the wires or the motor; or any damage esp. to the cables. If you can't trace it, think about buying a new pump. the RCD protection is very valuable, but it is inconvenient to have nuisance tripping.

The plug and socket should not be required, I gather you have an FCU. This should be fused at 3amps. If you can run a cable direct from that to the pump, you have fewer connections, thus less chance of anything going wrong.

There should not be a plug and socket inside the bathroom, nor just outside the door (as people might plug in hair dryers, heaters, radios and take them inside).

The FCU should also not be inside the bathroom, although there are some rules about zones which define this more closely.

One possible solution would be an RCBO which can protect a single circuit (since there might be a general background of slight leakages throughout the house which cumulatively reach about the 30mA trip point) but we are talking professional electrician here, not DIY. One way of looking for it is to unplug all watery appliances - washing machine, kettle, dishwasher; and switch off the immersion heater and boiler. If you have any outdoor sockets, lights, fountains or ponds on the RCD circuits, disconnect them. Then see if the shower still trips the RCD.

Check that Earth and Neutral are attached respectively to the G&Y and the Blue or Black cables correctly at all connections.

Do you know how old your Consumer unit is? What make? And does it have any spare positions?