What are the requirements for a device to be called "double insulated"?

[Commander Kinsey]

I'm not a health and softy wimp, but I was just wondering....

I have a black and decker hand held saw here. It claims to be double insulated, and does not have an earth. But the blade (and hence a metal workpiece) is electrically in contact all the way back to the spindle of the motor. And even worse, the switch only switches off the live and not the neutral - and since it's got one of those dodgy "UK plug clamped round the EU non-polarized plug" things, it was switching neutral, leaving live very close to all the metalwork inside including the blade, even when powered down. I assume in the EU, this saw would be connected like that 50% of the time depending which way round you put the plug in.

[David Wade]

If its double insulated, the switch only serves to stop its operation, its not a safety feature.

inside I would expect the live to be insulated, no bare terminals, so the heat shrink round the terminals forms one layer of insulation, the case the other. The shaft will be double protected as it passes through an insulated hub, and the wiring on the hub is also insulated....

.. and certainly in Spain so I assume in other countries every one was required to update their household wiring to include RCD protection so the risk of a fatality from electrocution is much lower than in the UK where many old houses still have no RCD or similar protection..

.. I believe similar rules in the UK would be more effective at saving lives than the mess that is Part P..

My neighbour is lucky to be alive after trying to clean her hair dryer with a nail file. #9she is in her 80's)

Dave

[Commander Kinsey]

It isn't. There are bare terminals everywhere.

I wouldn't trust that in a rotating motor which could shear something.

That would be an invasion of human rights. I do not have RCDs or ELCBs or GFCIs or whatever the politically correct term for the overly sensitive nuisance tripping things is. This house was built in 1979 and still has the original fusebox. No breakers.

Doesn't stop live to neutral, which is what made my neighbour fall off a ladder.

You need a weak heart to die at 240V. And if I wanted my life protecting, then I will decide to get a circuit breaker. But my life is my decision.

80s and still alive, I wonder why.

[NY]

My dad had a similar experience with a toaster. The switch that was operated when the bread was inserted turned out to switch the neutral wire (the plug

*was* wired the correct way round according to wire colours) and when dad stuck a knife in to retrieve a bit of bread that had fallen off, it shorted live to case-earth and blew fuse. No harm done, but he never made that mistake again! I think at the time my parents' "fuse box" still used fuses rather than MCBs and didn't have an RCD; since then the fuse box has been upgraded to MCB and at least a master RCD (if not one per circuit).

[Commander Kinsey]

In Merka there is no right way round, the plugs fit either way! That's if your lucky enough to have the right one of SEVENTY THREE different socket types in that room.

Wouldn't have helped having breakers. If he'd touched the live first then the earth he might have felt a slight tingle, unless he had his knee against a washing machine and was wearing shorts. But then if they didn't earth washing machines, the kitchen would be a lot safer!

My dad wrapped his fingers slightly round an old plug without sleeves (like the Merkin ones still are!) on a standard lamp and got a shock. Neither the breaker or the ELCB (the real name for RCD) tripped, because he just looked like a load.

[Peter]

Maybe she unplugged it before trying to clean it?

[Ralph Mowery]

It takes less than 120 volts to kill. It is not actually the voltage but the current. Onli 1/10 of an amp is enough to kill and most circuit breakere are 15 or more amps in the home.

[Brian Gaff]

Blimey, that must have cost the Spanish folk a lot of money. Mind you most of their wiring was make to and mend most of the time. I agree re the drill. I have a similar two speed drill, but I did notice that the cord was two wires inside a further layer of insulation, and the wires on mine were according to my Eyesight person brown and blue as they should be and the flat plug was placed in the adaptor the correct way around. I have never found any tickle from the chuck or other exposed metal parts like the gear changer, so it must work. I did in the end get a normal 13Amp plug fitted though, since the clamp on website was very non robust and seemed less than firm to me. Brian

[Dean Hoffman]

Some reading.

I think household wiring requirements change at 30 volts ac for doorbells and maybe irrigation systems.

[David Wade]

Nope there was a big bang and the fuse in the wall socket blew. She was shaking like a leaf, so I am pretty sure she got a nasty shock.

Dave

[SteveW]

ISTR figures from the report that John Prescott received showed that part P would save about 5 lives per year from electrocution - but the fire brigade calculated that increased fires from people retaining old wiring or using extensions, to avoid paying for "authorised" work, would cost 12 lives per year.

The suspicion was that it was all about establishing a paper trail for tax purposes.

[Thats All And Sign It]

Most of these "safety terms" are marketing buzzwords or legal loopholes.

[Commander Kinsey]

The earth leakage ones are 30 or 50mA.

[Commander Kinsey]

Yip, I spend money if and when I want to. Still got fuses here. The government has no right to make me safer than I want to be.

[Commander Kinsey]

I doubt it. Shaking is indicative of getting a fright, especially at that age. An electric shock doesn't make you shake.

Just aswell it wasn't in America where they never invented the fused plug. Or the sleeved pin plug. Then they make a fuss about GFCI or whatever they call them.

[Commander Kinsey]

Getting a shock would be difficult. She was in contact with the file. The file cannot be more than one voltage. Was she using two files, one in each hand?

[Commander Kinsey]

Even ignoring the 12, we should never produce mountains of paperwork just for 5 people.

[Commander Kinsey]

You do realise you don't have to get it authorised? Just do it yourself. All it says is work should be carried out by someone competant. That can be you, without official qualifications.

[David Wade]

No it can't. the legislation goes on to specify who can be a competent person, and it requires registration with a competent persons body...

.. if you are not on a register and you carry out notifiable work you must have it inspected..

[Tim+]

In which case surely you just say “It was like that when we moved here…”. ;-)

Tim