I have an adapter that goes from UK 3 pin to Euro/Swiss 2 pin.
It says on the adapter 'Does not provide an earth connection' and 'For class II appliances only'.
It seems to me this is a potentially dangerous plug to be on sale. Because if you don't read the plastic writing, or don't understand the consequences of the warnings above, you could easily plug in a UK device that needs earth and has a three pin plug, and plug it into a Swiss socket on two pins.
I'm not an electrician. Is the above correct and it's possibly dangerous? It is on sale in UK airports...
A double insulated item such as a hair dryer or a TV with only 2 wired cable, will be OK with a 2 pin plug, provided it is low powered .
An old metal cased laundry iron or electric clock will have a 3 wire cable and will definitely need an earth connection.
The major fire problems arise when people use too many devices on one Swiss plug, resulting in the connection overheating. The Swiss wall connection with the
3 small pins is only rated at a MAXIMUM of 10 Amps, which would be a MAXIMUM of 2'300 Watts (2.3 Kw) (Watts = Amps x Volts)
If you are using a multi strip UK style extension strip, YOU must ensure the TOTAL power taken is less than 10 Amps, a MAXIMUM of 2'300 Watts (2.3 kw)
If you have any doubts, please show someone qualified your equipment, and ask them!
It matters for loads of things with a metal case or parts and a non-double insulated power supply - and not just for electrical safety* but also for EMI compliance.
* not every home mains supply is fitted with an RCD.
To answer the question:
If you are travelling then apart from some laptop PSUs which are not class II, almost everything else that you would take is.
Stuff at home that usually needs an earth pin are microwave ovens, some kettles and some home audio equipment. (This list is not exhaustive)
If the device's safety label has one box outline inside another then it's class II and doesn't need an earth connection.
Even 60 year old electrical installations have fuses, so will blow if overloaded. Old installations will likely be 5 amps, later installations are 10 amps.
Yes, it's potentially dangerous. If you don't read instructions and plug in something that should have an earth, and there is short due to a device malfunction or a wiring issue you'll get electrocuted and die. Unless you have decent trips or fuses, in which case, they'll trip/blow and you'll be fine.
If it's supposed to not have an earth, don't plug in something that needs an earth. I'm not sure why anyone would find this difficult to understand this. On the other hand, if someone like my former landlord (an electrician by trade) has wired the house- you're dead.
If it shorts the fuse will blow, so most unlikely to die even if your holding the item. What is dangerous is if the live touches the case, the appliance will be live so then it's dangerous.
I have seen many metal ceiling lights are connected to a 2 wire system there the earth & neutral are combined. Seen this it in both CH & DE.
Tom1234 gave a practical set of guidelines at the end of his post - useful for me anyway.
As for NotAllThere and this comment - 'If it's supposed to not have an earth, don't plug in something that needs an earth. I'm not sure why anyone would find this difficult to understand this'. Well imagine that someone buys a 3 pin -> 2 pin plug for a legitimate reason. Then they leave it in a socket, or leave it lying around and someone else who is not knowledgeable picks it up and uses it for a UK 3-pin device that needs earth. Do you find it difficult to imagine that there should be good design of electrical fixtures, and prohibition of sale of potentially dangerous fixtures, to deter incorrect usage?
Whether it is low powered or not has got nothing to do with whether it needs a two or three pin plug. No current is carried in the ground (unless under fault conditions).
Define optional. Optional for the correct functioning of the equipment or optional to allow the piece of equipment to meet international safety standards and go on sale?
Both are important.
Merely a safety feature?
Nice to do . Not always possible - especially with equipment that requires a metal enclosure.
You can get rid of a lot of ground loops with good design, tying various equipment grounds to a common point and good filtering - even with audio equipment that features both high speed digital and analogue audio.
But of course you know that.
Of course there are those audio companies that fudge the results with their 'self-certification' to get their equipment out to market.