Double pole light switch vs single pole

[tarquin]

I have read that a double pole switch is a switch which breaks (or makes) both the live and neutral lines with one throw of the switch. Where are these switches typically used and what is the advantage. I think they are used in caravans and was wundering if they would also be advantagous to use in a house. Is that correct.

[BRADFORD]

They are used in caravans and other situations where the polarity could be easily reversed.
Not normally used in a house because if correctly wired and tested, the polarity will be correct.

[tarquin]

Thanks Bradford. I'm now wondering what happens if a light switch polarity is on the wrong way around. Does the light still work leaving the person in the dark as to their being a problem or will the light switch not work (turn on the light) if polarity is wrong.

[applied]

yes, correct if a light was accidently wired so that the neutral is switched a situation would exist that the globe and luminare would always be energized. this is highly dangerous and illegal.
this unfortunately is common in DIY wiring.

[tarquin]

Thank you Applied. I am glad to gain some insight on the matter. I am wondering now if a light switch polarity was wired wrongly is it something that an RCD would reasonably be expected to pick up. I have a particular interest in such things because my weekender has flat metal sheeting walls and I had some electrical work done in recent times and the sparky doing it got a shock. He was OK but was a worry. Apparently he drilled thru a light switch wire or screwed thru one when mounting the switch and then got a shock later from another room. He fixed the problem saying it's OK now and when promped to elaborate said it was isolated or insulated, I just forget which now. It's all made me just a bit nervous.

[applied]

if he drilled through the switch wire near the switch there is a good chance it was accessible enough to repair.
i don't know the setup of your house but there is a good chance there is no neutral in the switch anywhere anyway.
if you have a ELCB or RCD installed on the circuit it should pickup any active to earth and or neutral to earth connections.
If you are worried about reverse polarity at the light fitting get a multimeter on the pins in the holder and test for voltage when the switch is off or get on ebay and buy yourself a non contact voltage detector (VOLTSTICK) it will light up if put near a live power source eg; powerpoint or globe.
turn it to off and see if it lights up.
this is very general help i would not be worried any electrican worth his salt would not let this happen and besides the house would have been wired correctly in the start.
from experience if he told you it happened then he fixed it.

[Ashore]

Only one thing always test a ( VOLTSTICK ) on a known power source befoer using , they have thier own battery and if this is flat you won't get a warning. They are only a warnig devies and only work where power is being used . If you have any doubts , any at all, always isolate all power at the switchboard and remove fuses defore doing any work