How to power the Arduino from a UK light switch

Hi guys,

I'm currently working on a project which I plan to put behind a UK light socket faceplate. There is a live and an earth wire behind there. I want to know if there is a way I can power my Arduino project from here?

Thanks

NO NO NO

Consult a qualified electrician.

...R

Absolutley not.

Lightswitches in uk no not have a neutral.

If you use the earth the very best situation would be you trip a leakage breaker if you have one. They are not connected to lighting circuits in domestic situations any way.

Worst case various electrical devices in home will suddenly become live wrt local earth, FATAL.

Boardburner2: Absolutley not.

Lightswitches in uk no not have a neutral.

If you use the earth the very best situation would be you trip a leakage breaker if you have one. They are not connected to lighting circuits in domestic situations any way.

Worst case various electrical devices in home will suddenly become live wrt local earth, FATAL.

Wrong. In an UK outlet there is Phase, Neutral and Earth.

Still, unless EXACTLY you know what you are doing (and then you wouldn't ask here) i would not recommend to try it. It can go so very wrong.

// Per.

Wrong. In an UK outlet there is Phase, Neutral and Earth.

It's not an outlet, it's a light switch.

Boardburner2: Absolutley not.

Lightswitches in uk no not have a neutral.

The box behind the switch MAY have a neutral running through it, but as you say, it's NEVER connected to the switch.

If you use the earth the very best situation would be you trip a leakage breaker if you have one. They are not connected to lighting circuits in domestic situations any way.

All the circuits, including the lighting, in my house run through a leakage breaker in the fuse box. Damned annoying if it tripped after dark, until I installed a battery emergency lighting system.

Worst case various electrical devices in home will suddenly become live wrt local earth, FATAL.

No quibble there.

Boardburner2: Absolutley not.

Lightswitches in uk no not have a neutral.

If you use the earth the very best situation would be you trip a leakage breaker if you have one. They are not connected to lighting circuits in domestic situations any way.

Worst case various electrical devices in home will suddenly become live wrt local earth, FATAL.

So they just break the hot and don't bring the neutral in the box. There is ways of doing this but I wouldn't want some one with no idea of whats in the switch box putting his hand in there they use higher voltage over there.

Hi, I refuse to have anything apart from a light dimmer (approved) put behind a cover plate or in the ceiling.

[soapbox] We have Halogen Spots in Australia, most are 12V, so a power supply is needed, the dumb/stupid authorities allow the power supply (even thought is SMPS) in the dusty/insulation covered ceiling. Stupid idea, we have rats, possoms even snakes in ceilings in some parts of this country, rats and possoms p**s on things, they are not house trained, and a nice warm power supply is bliss.. Even though I live in a great country, they do DUMB THINGS just like others. [/soapbox]

Anything that is going dissipate heat, not matter what you use to drop the supply to 5V, WILL dissipate some heat, and wall cavities are not ventilated.

Tom..... :)

In the UK the lighting circuit is AC 2 wire.

It has also been a offence (in law- fines/ jail time) for any one, not qualified, to work on the mains wiring

Mark

I'm just wondering cause wire here is two wire too but your not counting the ground its sold as 14-2 and 12-2 for thing like wall outlets and lighting. but you still have all three wires.

Have a look at this http://www.discovercircuits.com/Andy/Parasiticpowersupply.pdf

All the circuits, including the lighting, in my house run through a leakage breaker in the fuse box. Damned annoying if it tripped after dark, until I installed a battery emergency lighting system.

That is precicely the reason that lighting circuits should be left off the circuit breaker , as should freezers and grannies iron lung be fed seperatley. Domesticly the breaker should only be on the downstairs ring or any where there is an external power supply, also the immersion heater which should have a dedicated feed.

The parasitic supply mentioned, this is the way lighting dimmers are powered, i have seen a few melted cases on those. Its a bad idea, could cause a fire and would give a real insurance problem if a fire occours and its not an approved device.

In the uk typically the switch is purely a dropped t and e switch pair so when the switch is on both red and black are live.

If a neutral is present its likely to be straight through with no slack to cut and get a connection.

I once used silicon thick gel to keep a 240v face plate attached to the walls lol just ran it across the top of the faceplate where it had come away from the wall as the screws had simply broke away from the walls, was that illegal? Lol

Dont know , but ive seen it before.

Stripped threads on a backbox are a fairly common and annoyingly difficult problem to fix.

TomGeorge:
[soapbox]
We have Halogen Spots in Australia, most are 12V, so a power supply is needed, the dumb/stupid authorities allow the power supply (even thought is SMPS) in the dusty/insulation covered ceiling.
Stupid idea, we have rats, possoms even snakes in ceilings in some parts of this country, rats and possoms p**s on things, they are not house trained, and a nice warm power supply is bliss… Even though I live in a great country, they do DUMB THINGS just like others.
[/soapbox]

Yes that was the case but you will find dichoric fittings ( which is what I think you are referring to) were required to be enclosed in a fireproof box however they are now pretty much out and replaced with LED fittings.

Still have the smps but run a lot cooler. Strict laws as to how and where to fit though just the same.

TomGeorge: Stupid idea, we have rats, poss*ums even snakes in ceilings in some parts of this country, rats and possums p*s on things, they are not house trained, and a nice warm power supply is bliss.

Tell me about it - I am not sure what - or how many is in the roof at present. Must get the missing tile fixed.

If you have a snake in there, you are lucky as you will have no problems (snakes are silent and oliguric) but if you think you have, you must not use rat poison.

Hi, snakes in roof not been reported in these parts, central highlands of victoria a bit cool, but possums and rats getting in out of the cold, yes.

Many many years ago, when there were District Radio Inspectors, they used to have problems with masthead amplifiers causing interference when they were lightning damaged or got wet and began to oscillate at VHF RF.

They became quite expert at finding the offending units, but they found one that was oscillating but the owner could not find the power supply for it. If they turn the GPO that the TV used, OFF, the interference stopped.

They took the wall plate off and the power supply was in the wall hard wired to the GPO outlet. It had burn marks similar to flash-over from lightning I gather.

Tom..... :)

Boardburner2: All the circuits, including the lighting, in my house run through a leakage breaker in the fuse box. Damned annoying if it tripped after dark, until I installed a battery emergency lighting system.

That is precicely the reason that lighting circuits should be left off the circuit breaker , as should freezers and grannies iron lung be fed seperatley.

How does one do that when the circuit breaker is part of the fusebox main switch, the one that's connected directly to the Supply Company's meter? Anyway, I'd sooner the food in the freezer defrosted than someone was electrocuted. The food can be replaced, people can't. Granny no longer needs an iron lung as she's 6ft under. =(

Modern boards are split. They have two rails with only one being fed from the rcd. Other is just switched.

Fwiw i have the same problem.

Henry_Best: How does one do that when the circuit breaker is part of the fusebox main switch, the one that's connected directly to the Supply Company's meter?

You get an electrician in to replace it with a proper one.

To have one RCD for everything is just dodgy "spec" building standard. I have three, but was talking to an electrician only last Friday about having my (inside) switchboard upgraded (now that RCDs are a more realistic price) to the six originally designed. But the lights are not included, nor is my refrigerator, nor should they be.

Henry_Best: Anyway, I'd sooner the food in the freezer defrosted than someone was electrocuted. The food can be replaced, people can't. Granny no longer needs an iron lung as she's 6ft under.

I was told that it is now required to have even the refrigerator on a RCD. Bureaucracy gone mad with incompetents in control. :0

I was also told last week by a lady that the Home Help (are required to) carry a RCD which they use when they use her vacuum cleaner, but other "help" who bring their own appliances, do not. This is of course because they cannot depend on an RCD being fitted (and operational) in the homes they visit, which may of course be (very) old. Mind you, she was not exactly sure what the device was, believing it to be the same as a surge suppressor adapter of which she happened to have one (Belkin, no less) sitting on the card table. And she may not have noticed that their appliances are fitted with a RCD which is the power plug. Also part of the discussion centred on the "power board" she had which was not working and she proposed to have her daughter take it back to Aldi. I had to explain to her that it would in fact, all work as long as she had the standard lamp turned on, as it was an "energy saver" Master-Slave power board.

I haven't investigated what they use for switching - likely a relay - as I haven't seen the point in them, so haven't even acquired one at a garage sale. The lady in question used to be in her family business in electrical repair.

In any case, the appropriate use of RCDs is of course for leaded mobile devices such as vacuum cleaners, hair driers, hair curlers, heaters, jugs, kettles, toasters, extension cords, entertainment units and such which may be damaged through use. That evanescent quality, common sense dictates that refrigerators and freezers are not such a risk as their power cords, being relatively fixed and indeed, concealed, are not subject to earth lead damage so that leakage to earth may occur (especially in washing machines) but cannot result in the casing or other exposed parts, becoming live and hazardous.

Medical systems are protected by 10mA (or 5 mA) RCDs instead of 30 mA and are fitted with (loud) alarms to immediately signal power failure. Were I compelled against that common sense, to have a RCD on my separate fridge circuit, that would of necessity be one with an alarm function.

And one final gripe - shoddy "spec-built" houses with one power outlet per bedroom, (all of two in the master), and at least one single power outlet to add insult to injury.

I think you would quickly change your mind about having an alarm type safety switch if you knew how much they charge for them (I do and it's not anywhere NEAR what you could imagine)

The need to have portable safety switches has been a requirement for quite some time especially for those working for government organisations. On construction sites it is mandatory to have them added on the end of every extension lead even though the outlet at the load centre is protected already. In fact safety switches in all wiring is almost a necessity these days (hospital operating rooms and the like aside which use LEMS) and about time too.