5 ms·

That mandatory switch, oh, Britain...

pmyteh 5y ago
Not mandatory, as it turns out - just ubiquitous. You can get similar sockets with no switch if you want them never to be turned off: https://www.edwardes.co.uk/products/mk-k781whi-2-gang-13-amp-un-switched-white-socket-outlet https://www.edwardes.co.uk/products/mk-k781whi-2-gang-13-amp...
petercooper 5y ago
230V though.. I don't know the reality, but I was brought up with them enough to feel unsafe just pulling out (or putting in) a plug without using the switch first :-D
- OJFord 5y ago
  Your risk unplugging anything (with a compliant plug & socket) is only really 'back EMF' from a poorly designed inductive load - you could get a jolt in significant excess of 230V, but low current, you'd be ok. A proper plug has coated pins near the grip, and the Earth will be too far removed (shutters closed) by the time you can get your hands on live & neutral contacts. Not doing you any harm to switch off of course, and there are certainly non-compliant plugs (cheap/knock-off stuff mainly of course) in the wild!
OJFord 5y ago
1) It's not mandatory; 2) How would you earth a PSU (with no built-in switch) & PC chassis for working on, for example, while not having it 'hot' in your country? Special plug/cable with L&N NC? We can just turn it off. That's arguably a bit of a contrived example, but it is handy to have an ever-present switch to isolate things, and some things are always on standby while powered. Battery chargers & power tools typically, for example.
- pmontra 5y ago
  I second your feelings. There is a module for a switch (I got one on my air conditioner) but it's uncommon. When I need one (example: TV) either I build a cable with a switch or I plug it in a power strip (example: RPi and USB hub). I buy only ones with individual switches on every socket.
- newaccount74 5y ago
  Having something plugged in but switched off while working on it sounds pretty dangerous. I always unplug things before working on them. It's too easy to think something is switched off when it isn't, or to flick a switch without thinking. (I don't ground stuff that I'm working on)
  - DaiPlusPlus 5y ago
    > Having something plugged in but switched off while working on it sounds pretty dangerous. The switch on the socket physically disconnects the "hot" / live supply from the receptacle for the plug's live pin while leaving the Neutral and Ground still connected (some models might also disconnect Neutral just-in-case your house is miswired, but don't quote me on that). The switches also have a very vibrant red strip that's only visible when the switch is in the On position, never Off - so I can assure you it's the complete opposite of "pretty dangerous". For example: https://www.readersdigest.co.uk/media/images/screen-shot-2016-01-18-at-11.54.39.jpg https://www.readersdigest.co.uk/media/images/screen-shot-201... If you leave a computer or other EM-sensitive appliance connected to mains but with the switch off then the ground connection is maintained, so you can safely use the computer's own chassis to de-static-ify yourself without the need for a fiddly wrist-strap.
    - newaccount74 5y ago
      The problem is when you go back and forth between trying if it worked, turning power on and off again, and at some point you become sloppy and forget that you didn't turn it off. I've electroshocked myself twice while working on appliances (not PCs). After going back and forth a few times I thought I had turned off the circuit breaker (which also has a vibrant red strip to show that it's hot) but I didn't and touched the live wire. If you look at safety guidelines for electricians, they require people to have multiple safeguards in place so that a single mistake doesn't kill you. That being said, household voltages probably won't kill you and some people open PC cases while they are running, so there's that. As long as you're not messing with the power supply I don't think PCs are really that dangerous.
- outadoc 5y ago
  > PSU (with no built-in switch) Never encountered one
  - OJFord 5y ago
    Well they do exist, I have a couple, and that's not really the point, it's just an example. Imagine yours doesn't.

Not mandatory, as it turns out - just ubiquitous. You can get similar sockets with no switch if you want them never to be turned off: https://www.edwardes.co.uk/products/mk-k781whi-2-gang-13-amp-un-switched-white-socket-outlet https://www.edwardes.co.uk/products/mk-k781whi-2-gang-13-amp...

petercooper 5y ago

230V though.. I don't know the reality, but I was brought up with them enough to feel unsafe just pulling out (or putting in) a plug without using the switch first :-D

OJFord 5y ago
Your risk unplugging anything (with a compliant plug & socket) is only really 'back EMF' from a poorly designed inductive load - you could get a jolt in significant excess of 230V, but low current, you'd be ok. A proper plug has coated pins near the grip, and the Earth will be too far removed (shutters closed) by the time you can get your hands on live & neutral contacts. Not doing you any harm to switch off of course, and there are certainly non-compliant plugs (cheap/knock-off stuff mainly of course) in the wild!

OJFord 5y ago

1) It's not mandatory; 2) How would you earth a PSU (with no built-in switch) & PC chassis for working on, for example, while not having it 'hot' in your country? Special plug/cable with L&N NC? We can just turn it off. That's arguably a bit of a contrived example, but it is handy to have an ever-present switch to isolate things, and some things are always on standby while powered. Battery chargers & power tools typically, for example.

pmontra 5y ago
I second your feelings. There is a module for a switch (I got one on my air conditioner) but it's uncommon. When I need one (example: TV) either I build a cable with a switch or I plug it in a power strip (example: RPi and USB hub). I buy only ones with individual switches on every socket.
newaccount74 5y ago
Having something plugged in but switched off while working on it sounds pretty dangerous. I always unplug things before working on them. It's too easy to think something is switched off when it isn't, or to flick a switch without thinking. (I don't ground stuff that I'm working on)
- DaiPlusPlus 5y ago
  > Having something plugged in but switched off while working on it sounds pretty dangerous. The switch on the socket physically disconnects the "hot" / live supply from the receptacle for the plug's live pin while leaving the Neutral and Ground still connected (some models might also disconnect Neutral just-in-case your house is miswired, but don't quote me on that). The switches also have a very vibrant red strip that's only visible when the switch is in the On position, never Off - so I can assure you it's the complete opposite of "pretty dangerous". For example: https://www.readersdigest.co.uk/media/images/screen-shot-2016-01-18-at-11.54.39.jpg https://www.readersdigest.co.uk/media/images/screen-shot-201... If you leave a computer or other EM-sensitive appliance connected to mains but with the switch off then the ground connection is maintained, so you can safely use the computer's own chassis to de-static-ify yourself without the need for a fiddly wrist-strap.
  - newaccount74 5y ago
    The problem is when you go back and forth between trying if it worked, turning power on and off again, and at some point you become sloppy and forget that you didn't turn it off. I've electroshocked myself twice while working on appliances (not PCs). After going back and forth a few times I thought I had turned off the circuit breaker (which also has a vibrant red strip to show that it's hot) but I didn't and touched the live wire. If you look at safety guidelines for electricians, they require people to have multiple safeguards in place so that a single mistake doesn't kill you. That being said, household voltages probably won't kill you and some people open PC cases while they are running, so there's that. As long as you're not messing with the power supply I don't think PCs are really that dangerous.
outadoc 5y ago
> PSU (with no built-in switch) Never encountered one
- OJFord 5y ago
  Well they do exist, I have a couple, and that's not really the point, it's just an example. Imagine yours doesn't.