We have a new cooker to install in the house.
The electrician has installed a socket for the cooker that has 3 square holes in it and we have obtained an appropriate large 3 flat pin plug.

One pin of the plug is bigger than the rest.

It is my assumption is that the earth wire goes into the biggest pin and it doesnt matter which pin takes the other 2 wire.

Can anyone confirm please

Also have a second question re my cooker that I will open a new thread

It is important that the phase and neutral are connected to the correct pins otherwise the appliance will still be live when it is apparently switched off.

There is no indication on the plug because there is, unbelievably, no rule about which side they should be on. You will need to use a screwdriver with a neon bulb in the handle to ascertain which side of the socket is phase and which side is neutral and wire the plug accordingly.

Thankfully this type of plug can only be inserted one way round unlike the smaller round plugs which can be plugged in either way round.

For a country with so many rules and regulations about everything under the sun this is incredible but true.

Actually, this isn't a dangerous condition, unless you decided to tear down the appliance whilst the supply was still connected. The switch on an appliance is never considered as a form of isolation. You simply unplug the device first.

Remember that both phase and neutral should both be considered 'live' which is why circuit boards in Spain are normally wired with double pole circuit breakers which provide effective isolation compared to single pole breakers back in the UK.

Always assume that an appliance is live unless you've personally disconnected it from both phase and neutral conductors first. Assuming that an appliance is 'safe' just because a single brown / red / grey or black wire isn't connected could prove potentially fatal.

All appliances sold today with the CE should have double pole switches, so the issue of polarity is not relevant, however this was not the case with older equipments especially bought from the UK, wherein on a lot of appliances up to a few years ago only had single pole switches, hence UK power outlets were switched and correct wiring was important. SO if your bringing an appliance from the UK and it is a few years old you should just check to be sure.
In any event ensuring that an equipment is disconnected from the mains can only be done by Isolation as Beachcomber says

We are talking about a cooker here where the socket is probably behind the appliance so cannot be unplugged when it is not in use.

The switches controlled by various knobs on the cooker are not double pole and I have seen several hobs which, although switched off, still have a pilot light showing.

Also light switches, for example, are not double pole which means that if phase is not matched to phase the light socket is still live even though it is switched off. Table lamps with single pole in-line switches remain live if the switch is not in the phase line.

Switches for lights, table lamps, appliances, etc, etc, etc are simply a 'courtesy' feature to enable you to turn things on and off. These types of switches cannot ever be used for isolation because they (1) fail to provide positive indication of closed contacts, and (2) have insuficient creepage and clearance distances, so how your appliance is wired is completely irrelevant.

If you flick the switch on your correctly-wired table lamp, then in the event of an over-voltage condition, a lost-neutral condition, a contact-weld condition, or several other conditions too complicated to mention, you will still die of electrocution when you change the bulb.

All appliances are 'live' until you unplug them or isolate them at the circuit board with a double pole switch. The BS1363 plug and socket setup that we are all used to in the UK doesn't make us any safer. It just makes us think we're safer.

I thought that the earth leakage trip (ELCB or whatever it is called) is supposed to stop you electrocuting yourself - or is that another Spanish electricians myth?

Quite right. The ECLB monitors the current in both supply and return. A very small difference is assumed to be going where it shouldn't and trips the supply. However, why take the risk. Unplug if you can. Use twin pole switches where possible and check the polarity with the neon screwdriver.

Sort of. The RCD (Residual Current Device - the ELCB is a different and much older and less reliable system) is designed to provide a layer of active safety - much like an airbag in a car.

Having an airbag doesn't mean I typically drive into walls and other cars. It's there as a 'last resort'.

In any case, there are other reasons an RCD might not save you...

For example, if it's faulty (and when was the last time you tested yours?). Or if you're left handed with a heart condition, 30ms @ 110mA might still be long enough to cause you to go into VF.

Or you are simply changing a bulb on a ceiling mounted luminaire - where the jolt causes you to slip from your ladder and you break your neck on the beautifully tiled floor below.

Yes, RCD - I thought it wasn't ELCB anymore - weren't they the things you fitted to electric mowers in the UK?

That raises a question. I think RCD's are now more common in the UK but they certainly didn't used to be. In Spain I think they have been in use for a long time.

Is that maybe why the UK system always tended to be more protected with individual fuses and safer wiring, because if you got it wrong you could not rely on another safety device helping you?

http://en.wikipedia.org/wiki/Earth_l...ircuit_breaker

The fuse/cb is only really to protect the installation (cable) whereas the the RCD/ELCB protects the user.

are all you lot bright sparks

The ELCB technically only measures leakage down the ECC path - either by current through or (more usually) voltage across. As a result, it provides NO protection for earth faults that don't pass down the ECC i.e. most user protection.

The BS1362 fuse is really only there to protect the cable, however the single pole fuse / circuit breaker in a UK distribution board WILL provide user protection by virtue of automatic disconnection in the event of an earth fault occuring within a class 1 appliance.

This feature does, however, rely on a good earth and (of course) correct polarity... which then brings us full-circle and goes some way to explaining why polarity (what's live and neutral) matters in UK installations and doesn't in Spanish ones.