Automation and using in the home - Is it legally safe?

[neo8223]

Really not sure if this is the right place to post this question however, I've recently become a home owner and really like the idea of home automation.

However, buying off the shelf stuff costs an arm and a leg, and sometimes can't do everything you want. Fortunately, Raspberry pi is on hand to control your home and with the help of a bit of fancy coding and a couple cheap components from eBay that were made in China, you can pretty much do anything you want.

Say I want to switch on my bathroom extractor using a DHT22 humidity sensor for example as the input sensor, then add a relay to switch on and off the extractor. I know that its electrically safe, the relay can take up to 250v @ 10A, the extractor uses 4.5w, so we're talking 0.02amp load. I can also ensure that the power source to the raspberry pi originates outside of my bathroom, coming from a wall socket.

But killer question, would attaching that relay to act as an on/off switch for the bathroom be considered safe, and legally allowed? And if not, then whats a good way around it?

[karrika]

The legal part depends of where you live. Mixing bathroom 10A and 250V in Finland is illegal in pretty much all combinations. There is a ton of regulations of how you have to do the wiring. Taking the power from a wall socket outside the bathroom is also illegal. But this is Finland. You may have more luck doing this in some less regulated country.

A good way around this is to ask a licensed electrician to approve the design and do the wiring so that all regulations are taken into account.

[B.Goode]

would attaching that relay to act as an on/off switch for the bathroom be considered safe, and legally allowed? And if not, then whats a good way around it?

Formal definitions of 'safe' and 'legal' will depend on the Regulations and Legislation where you live. Since you don't mention that there can be no definitive answer.

In the UK domestic electrical wiring has to comply with The Wiring Regulations.

And I think I am correct in saying that installations and modifications can only be carried out (or inspected and signed off as safe) by a qualified tradesman.

Wherever you live, mains electricity can kill. And it might not kill you, but a member of your family or a future owner of the property. This is an instance where the fact that you need to ask the question suggests that you are not qualified to understand the risks.

Please seek professional advice before proceeding.

In the UK the incremental cost of upgrading an extractor fan to a 'humistat' model is about £30 based on one sample from a Screwfix catalogue. That's the way round it.

[btidey]

If one wants to do extensive automation then one possible approach is to use already approved RF remote controlled units (switches, dimmers, relays) from companies like Energenie or LightwaveRF and then use a Pi Automation software together with an RF transmitter module to talk to the units without worrying about direct wiring.

[neo8223]

Hi all, Thanks for the replies. Have opened my eyes considerably.

I do live in the UK so its good to know that legislation. I didn't know that Humidistats even exist!, so you've opened my world. I much prefer that idea to using a relay and home brew kit. Especially that it doesnt need to be IOT.

http://www.ebay.co.uk/itm/STY100H-4-100 ... 3641.l6368

My reason for wanting to use pi or arduino is that these smart switches are just so expensive! With that said, getting a sparkie in each time is equally expensive.

Thanks for all of the replies.

[bensimmo]

would attaching that relay to act as an on/off switch for the bathroom be considered safe, and legally allowed? And if not, then whats a good way around it?

Formal definitions of 'safe' and 'legal' will depend on the Regulations and Legislation where you live. Since you don't mention that there can be no definitive answer.

In the UK domestic electrical wiring has to comply with The Wiring Regulations.

And I think I am correct in saying that installations and modifications can only be carried out (or inspected and signed off as safe) by a qualified tradesman.

Wherever you live, mains electricity can kill. And it might not kill you, but a member of your family or a future owner of the property. This is an instance where the fact that you need to ask the question suggests that you are not qualified to understand the risks.

Please seek professional advice before proceeding.

In the UK the incremental cost of upgrading an extractor fan to a 'humistat' model is about £30 based on one sample from a Screwfix catalogue. That's the way round it.

Qualified Tradesman...
Well Competent Person is the wording or there abouts, this allows home DIY, also altering things is less 'hassle', changing whole rings is usually more difficult. But if you know what you are doing then all should be ok.
anything that has to certified you can call the council to come check it. (Double check if you need to and who would do it)
Though quite often for large things it's easier and cheaper to get a sparky in and they can self certify.

For bathrooms, read the zonal info, but as the Pi and sensor will be down at 5V there is no problem there, keep the 230V to above the ceiling and also it's good practice to use an isolator switch for the extractor.
While many pop them above doors, it's a better idea to out it somewhere people can actually reach it

But if you are not competent, don't do it and seek better advice, by all means design it though.

[DanSolo81]

Hi All,

I'm a rookie to the Pi, but I'm a member of International Brotherhood of Electrical Workers in the US. While my scope of work is low voltage communications specifically. But I know that no electrical contractor or journeyman can install or approve an installation of a device that does not meet the regulations laid out in the NEC (National Electrical Code). One such regulation is UL (Underwriter's Laboratory) Listing. This means that UL has tested the device or product and have determined that it meets their standards of safety. Again, that's here in the US, I'm not sure about other countries, but I assume they have something similar in place to protect you.

[stderr]

I know that no electrical contractor or journeyman can install or approve an installation of a device that does not meet the regulations laid out in the NEC (National Electrical Code). One such regulation is UL (Underwriter's Laboratory) Listing. This means that UL has tested the device or product and have determined that it meets their standards of safety.

What you are saying is that all home made systems for automation are illegal and we must instead buy only UL approved schemes that don't work with Linux and instead spend all their efforts spying on you and sending your information back to their home base in China, Moscow, that big weird blast proof building in New York City, Redmond, Cupertino or especially Seattle.

[neo8223]

Qualified Tradesman...
Well Competent Person is the wording or there abouts, this allows home DIY, also altering things is less 'hassle', changing whole rings is usually more difficult. But if you know what you are doing then all should be ok.
anything that has to certified you can call the council to come check it. (Double check if you need to and who would do it)
Though quite often for large things it's easier and cheaper to get a sparky in and they can self certify.

For bathrooms, read the zonal info, but as the Pi and sensor will be down at 5V there is no problem there, keep the 230V to above the ceiling and also it's good practice to use an isolator switch for the extractor.
While many pop them above doors, it's a better idea to out it somewhere people can actually reach it

But if you are not competent, don't do it and seek better advice, by all means design it though.

Thanks Benisimmo, really helpful. The first thing I did when I bought the flat was re-wire it, I got a sparkie to test it and give it the certificate, so I'd say I'm competent to do within the realms of a home wiring jobby. [I have developed a special hatred for 6mm twin and earth ] He also approved a 5V USB socket in zone 3 of the bathroom, which runs off a spur on the main ring.

One other scenario in the bathroom is that I have a bluetooth light/speaker hooked up in zone 3 of the bathroom. Annoyingly, its only got live, earth and neutral, with no switched live. This means that when the lights switched off, I cant play out of the speaker, so need to use the remote control that it comes with to switch on/off the light. I thought that was crap, so I cloned the remote codes and bought a HC-SR501 motion sensor which I eventually want to put in the ceiling, and moved the light switch into a cupboard. (to be permanently on) For now, whilst i decorate the room, I am using the remote that comes with it, but the idea is for the arduino/pi to sends on/off signals via led when it detects motion/or lack of.

To avoid calling the council, going back to your point, if I plug the pi into another room, powered via a socket (keeping the 230v outside the room) and then have a long wire connecting to an LED and the motion sensor which I mount to the ceiling with a dry lining box, and cutting out a blanking plate with a nice dob of silicone, would that be deemed as safe? It'd be] in zone 3 territory in the ceiling.

If i were to call the council for other projects that say did involve using a relay directly to the mains, ie lighting, what would I need to say so they understand what I'm asking of them?

[stevend]

From the safety perspective, there are often two main areas to consider:
a) Powering the control system (i.e. Raspberry Pi and ancillaries). Legislation is probably satisfied by ensuring that the power supply used meets local safety standards (UL, CE etc).
b) The interface to any mains-powered circuitry. Sometimes compliance will occur naturally; using radio controlled switches for example. Other times it's mostly a matter of using components which meet relevant safety standards and are mounted and wired to maintain isolation between mains and low voltage, correct earthing etc. This can take more research to find out what the rules are, or which standards the components must meet.

In some cases it may be necessary to consider things such as heat dissipation, as well.

Whether formal approval of any 'home made' equipment is required will depend on the country; often it is only necessary if the product is being sold commercially ('put on the market'), in which case 'personal' use is OK (but doesn't excuse poor construction!). In the UK at least, the bigger problem might be explaining to your insurance company if the house is set on fire by your automation system.

There are obviously other things, such as EMC, to consider.

And, regardless of local regulations, it should be obvious that when messing about with mains voltages, only do so if you know what you're doing.


On the subject of domestic wiring specifically in the UK, you can do quite a lot yourself without needing to get any formal approvals (look up 'Part P'). Bathrooms (and outside) generally do need the electrics signed off by someone with the right bits of paper - what you can fit depends on where it is in relation to baths and showers and so on. This is an area you need to approach with caution; many electricians are likely to be reluctant to sign off an installation they haven't been involved with; all the more so if it involves unfamiliar bits. I've not approached my local council about getting stuff signed off, but have read that their approach varies - apparently some will do the necessary inspection/testing themselves, while others basically tell you to get someone to sign it off and then rubber stamp the paperwork. So could get expensive.

In answer to your specific question, I'm pretty confident that if you only run low voltage into Zone 3, derived from a power supply with UK safety approvals (i.e. CE-marked) you don't need to involve the council.

[neo8223]

Hi All,

I'm a rookie to the Pi, but I'm a member of International Brotherhood of Electrical Workers in the US. While my scope of work is low voltage communications specifically. But I know that no electrical contractor or journeyman can install or approve an installation of a device that does not meet the regulations laid out in the NEC (National Electrical Code). One such regulation is UL (Underwriter's Laboratory) Listing. This means that UL has tested the device or product and have determined that it meets their standards of safety. Again, that's here in the US, I'm not sure about other countries, but I assume they have something similar in place to protect you.

Thats what I was afraid of too in the uk. Lets face it, goods from China on ebay don't have the best of reputation and have been known to be unsafe and even use fake markings, apple chargers for example. In Europe, we have CE which stands for: "Conformité Européene" for all low voltage goods. One of my original ideas was to bastardise a small usb charger (made by plantronics) that I may have liberated from work (but know its the real mccoy), connect it to a 3amp fused switched outlet and do away with the 3 pin plug. But then I had the worry of living in a flat and "what if" came to mind.

I'm glad the UK seems a little more lenient however.

[bensimmo]

Flats are more difficult iirc and a bit more stringent. (it's been some time since I looked at it or lived in a flat) mainly as there are other people in the building and you often you don't actually own the actual building.

Check up the regulations, it's worth it.

I would have thought if the relay is a good as a switch, like any other light switch, it is just like wiring a switch in.
Just use something appropriate, but check up from someone/people who have done it and looked into it recently.

[fruit-uk]

Take a look at some of the european devices, perhaps from Germany as a start eg. http://www.conrad-electronic.co.uk/ce/e ... .ASTPCEN22 although that seems to have expanded omewhat since I last looked!
https://www.elv.de/ is good too if you can find your way around

Take a look at http://fhem.de and perhaps http://www.ply.me.uk/bits_and_pieces/fhem.html too

[boyoh]

Qualified Tradesman...
Well Competent Person is the wording or there abouts, this allows home DIY, also altering things is less 'hassle', changing whole rings is usually more difficult. But if you know what you are doing then all should be ok.
anything that has to certified you can call the council to come check it. (Double check if you need to and who would do it)
Though quite often for large things it's easier and cheaper to get a sparky in and they can self certify.

For bathrooms, read the zonal info, but as the Pi and sensor will be down at 5V there is no problem there, keep the 230V to above the ceiling and also it's good practice to use an isolator switch for the extractor.
While many pop them above doors, it's a better idea to out it somewhere people can actually reach it

But if you are not competent, don't do it and seek better advice, by all means design it though.

Thanks Benisimmo, really helpful. The first thing I did when I bought the flat was re-wire it, I got a sparkie to test it and give it the certificate, so I'd say I'm competent to do within the realms of a home wiring jobby. [I have developed a special hatred for 6mm twin and earth ] He also approved a 5V USB socket in zone 3 of the bathroom, which runs off a spur on the main ring.

One other scenario in the bathroom is that I have a bluetooth light/speaker hooked up in zone 3 of the bathroom. Annoyingly, its only got live, earth and neutral, with no switched live. This means that when the lights switched off, I cant play out of the speaker, so need to use the remote control that it comes with to switch on/off the light. I thought that was crap, so I cloned the remote codes and bought a HC-SR501 motion sensor which I eventually want to put in the ceiling, and moved the light switch into a cupboard. (to be permanently on) For now, whilst i decorate the room, I am using the remote that comes with it, but the idea is for the arduino/pi to sends on/off signals via led when it detects motion/or lack of.

To avoid calling the council, going back to your point, if I plug the pi into another room, powered via a socket (keeping the 230v outside the room) and then have a long wire connecting to an LED and the motion sensor which I mount to the ceiling with a dry lining box, and cutting out a blanking plate with a nice dob of silicone, would that be deemed as safe? It'd be] in zone 3 territory in the ceiling.

If i were to call the council for other projects that say did involve using a relay directly to the mains, ie lighting, what would I need to say so they understand what I'm asking of them?

Qualified Tradesman = Skilled at is Trade

Competent Person = Jack of All Trades But Master of Non

Advice The Electrician Who Passed Your Installation, Ask him
All the questions you are asking the forum ?

[stevend]

Qualified Tradesman = Skilled at is Trade

That's the theory; regrettably not always the case. And many are likely to struggle with the sort of things people here are trying to do. (I've come across an experienced plumber who couldn't diagnose a problem with a thermostatic mixer valve, and several who are incapable of dealing with even simple electrical issues).

Competent Person = Jack of All Trades But Master of Non

Sometimes. Or maybe they've just never gained the relevant piece of paper. I've come across extremely competent people without a piece of paper to their name.

[boyoh]

Qualified Tradesman = Skilled at is Trade

That's the theory; regrettably not always the case. And many are likely to struggle with the sort of things people here are trying to do. (I've come across an experienced plumber who couldn't diagnose a problem with a thermostatic mixer valve, and several who are incapable of dealing with even simple electrical issues).

Competent Person = Jack of All Trades But Master of Non

Sometimes. Or maybe they've just never gained the relevant piece of paper. I've come across extremely competent people without a piece of paper to their name.

I can't argue about the ability of some tradesman , and competent men. There are good and bad.
But in fairness ,you have to take them at face value, If you have not seen the qulity of their work
The trouble today is the short apprentice time, My electrical apprentice time was 7years, Started
In 1945 age 14 / 21. Then 2yrs National Service before I could reap the rewards of full money
I'm 85 now, retired 21yrs and would do the same job all over again, I was only happy with my
Head stuck inside a control panel. The Raspberry Pi keeps my brain active. I think I can sort
The good from the bad

Regards BoyOh. Retired Electrical / Electronic / Technician

[hippy]

In answer to your specific question, I'm pretty confident that if you only run low voltage into Zone 3, derived from a power supply with UK safety approvals (i.e. CE-marked) you don't need to involve the council.

I would agree with that. I have powered speakers, PIR, pressure sensor mats and door sensors in my bathroom all connected to kit which is actually in an adjacent room. I am happy with that and it complying with regs and would be happy adding light, temperature or humidity sensors. It's all low voltage ( nothing over 12V ) though I did consider what would happen if something failed and mains ended up on the wiring.

Running mains is a different matter. You need to check Part P of the Building Regulations to verify what exactly needs notifying and certifying -

https://www.gov.uk/government/publicati ... document-p

A trick for getting a sparky to certify is to get them to certify without the 'box of magic' they don't / won't understand. Wire a junction box outside the room for the spur to whatever needs mains power, get that all certified, then break the junction box and insert your control gear. As long as you are confident in its safeness you shouldn't be compromising safety nor the certification given and adding the control gear should not require certification itself.

One thing to note is that, where certification is required, self-certification these days is only allowed by "a registered competent person"; merely being competent is no longer sufficient.