Single, double pole plug sockets?
Question:I understand double pole switches the neutral off as well as the live. but why would you need to? and if dangerous, why are not all sockets double pole?
Answers:
They are a BS7671 requirement for circuits supplied by generators. Not a requirment for 'ordinary' circuits.
It's to stop a big back emf coming down the neutral to bite yer, when the load on the end of the circuit gets switched off.
Cooker isolators are double-pole as are showers.
Single-pole sockets are still produced, presumabably on cost grounds. I never fit 'em myself, double pole every time.
A double pole switch switches two circuits simutaneoulsy. They are usually used on circuts that may be exposed to weather to prevent electric shock from groud loops and on 220 volt circuits where you don't have an earth neutral.
This type of switch is normally used for high current circuits where an electrocution would be deadly.
Bear in mind you can have thousands of volts pass through you but at a low current it does you no harm.
As they are more expensive they aren't fitted where they aren't needed.
You are correct in that double pole sockets switch off both live and neutral at the same time, in a similar manner to FCUs (fused connection units).
It is a more secure way of disconnecting the supply, but does not mean that single pole switches are more hazardous, just a bit cheaper in cost.
Light switches also work by just disrupting the live supply.
There is no doubt that single pole switches are more dangerous! As they require more care when wiring.
Where this shows up at its most dangerous, is when taking a UK made caravan to Europe.
In Europe all switches are required to be double pole and because of this European caravan sites electric hook- ups can be dangerous when plugging in a UK made caravan - there is always the possibility that the live feed will come in on the negative wire, leaving everything live when switched off.
It is probably a matter of tradition (and cost) that we are different. Luckily some double pole switches are finding their way into the shops.
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