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Are there any rules and regulations for using electronic devices built by a user in his own house in the UK?

Like for example, if I build a DMX control system (from scratch - i.e. PCB and enclosures etc) to control my lights in my home, do I have to comply to any regulations like the big companies do?

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  • \$\begingroup\$ Where do you live? \$\endgroup\$ – Ariser Oct 17 '16 at 11:35
  • \$\begingroup\$ Hey, I live in the UK \$\endgroup\$ – LabMat Oct 17 '16 at 11:36
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    \$\begingroup\$ Mains powered devices installed in the house (modifications to the house wiring) yes there are. With good reason - to protect its future occupants. Devices you sell ... yes. Devices you plug in to standard outlets and sockets - pretty much no. As long as they don't wipe out your neighbour's radio or TV reception, go ahead. But check your insurance policy for exclusions on electrical fires. \$\endgroup\$ – Brian Drummond Oct 17 '16 at 11:48
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Generally spoken: No plaintiff, no judge. Which means, you may violate a lot of codes and regulations, but nobody will care, as long as you don't stir up too much dirt.

CE is a set of rules you have to follow, when you like to sell something in the EU (to which you still belong). As long as you don't sell things, you don't have to state compliance with those regulations. OFCOM will only kick your ass, if someone complains about your EMI.

But with electricity there are some nifty details, as you should know.

  1. Electricity can kill people
  2. Electric devices (exempt incandescent bulbs and toasters) emit electromagnetic radiation
  3. Malfunction in electric devices can start fires and damage cabling and other devices

If you follow all rules and codes, you have already done much to fend off any detrimental effects of your DIY project. This does not save you from nasty legal consequences if your devices fail despite all countermeasures you have taken. If you aren't an engineer who has an insurance for the risks connected to your job, you may be held liable for damage, even if codes were followed thoroughly, because codes and rules are only covering a part of all possible mistakes. Only people with sufficient insight (i.e. engineers, electricians etc.) are considered to be aware of all lurking risks. If you aren't one of these, you ought to know, that electricity is dangerous and you shouldn't fiddle around with it.

Implications may be:

  • Fire insurance refusing to pay
  • liability for personal injury (not as expensive as in the US but painful nevertheless)
  • custodial sentence possible in case of personal injury
  • monetary fines due to violation of OFCOM rules. Usually only if someone complains about the EMI you were causing.

But if you decide to do your own design and decide not to comply with all rules and regulations you have to take some additional risks. This applies to people with sufficient knowledge even more. So if you are an engineer (who should have known better) and build a device which harms people you will encounter no pity in front of a judge.

Additional implications, if you should have known better:

  • fire insurance will refuse to pay in case of fire caused by equipment, for sure
  • private liability insurance may refuse to pay if you knowingly violated codes
  • accusation will be concerning gross neglegience instead of slight fault.
  • even the assumption of wilful intent is possible.
  • loss of job (as your professional seriousness is in doubt)
  • occupational ban

A good start for not risking jail and a life in poverty and remorse is to use off the shelf walwarts as power supply and only deal with SELV circuitry in your own design. Then it will be rather unlikely to kill or harm people with your circuitry. The EMI-risk is per se rather low as long as you do not try to build your own oscillators and wireless transmission devices.

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  • \$\begingroup\$ Thanks man. As I mentioned in the later post, I don't intend to do any mains stuff. It will all be DC and well within 24VDC. With regards to wireless transmision devices, I do intend to build my own bluetooth receiver. \$\endgroup\$ – LabMat Oct 17 '16 at 12:51
  • \$\begingroup\$ Build your own bluetooth? I assume you mean incorporate an off the self radio module. If this is for your own use, not an issue. If for sale then depending on the certifications that the module has and exactly how it is used this could be anything from 1 line on a piece of paper that you supply with the product or several days extra in a testing lab and a LOT of paperwork. \$\endgroup\$ – Andrew Oct 17 '16 at 12:58
  • \$\begingroup\$ To sell Bluetooth or use the name there can be quite significant licensing fees involved. \$\endgroup\$ – Spehro Pefhany Oct 17 '16 at 15:41
  • \$\begingroup\$ Ah. ok... @Andrew - Yes thats what I meant... Incorporating an off the shelf bluetooth receiver IC. \$\endgroup\$ – LabMat Oct 18 '16 at 8:42
  • \$\begingroup\$ A bit harsh. I agree completely with getting a certified low voltage (<48VDC) power supply for electrical safety. For fire etc there's a low power limit which is considered low hazard but I don't want to go on a limb and give an exact figure without checking. <5W at least qualifies so a 12V 0.5A supply is safe. Wrt no pity in front of a judge, it's not that straightforward as something you build at work may still fail catastrophically with no jail time. This of course depends on investigation, quality controls (if any), type testing (if any) and so on. \$\endgroup\$ – Barleyman Nov 16 '16 at 14:06
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Legally I have no idea but as long as you don't plan to sell the system and you can remove it if you move out then I very much doubt anyone is going to come and arrest you.
Worst case you'll have to turn it off is someone complains that it's causing interference of some kind.

However keep in mind that if you've wired up something you made yourself into the mains wiring you can be sure that your insurance company is going to reject any claims caused by electrical problems. It doesn't matter what the cause of the problem actually is, insurance companies will use any excuse they can.

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  • \$\begingroup\$ Hey thanks. I'll be using an off the shelf AC-DC switching supply which I will wire a UK plug and connect it to the mains outlet. It can be 9/12/24V DC. Ill only be designing the final product that takes in DC power. No mains operation. Now if I put this mains PSU and this product in an enclosure, do I have to comply with any regulations? \$\endgroup\$ – LabMat Oct 17 '16 at 12:20
  • \$\begingroup\$ Only if you want to sell it. Any product you sell will need to meet the relevant emissions regulations. This is a self certification process in the EU however you are still required to show due diligence and reasonable grounds for believing that you comply. For new products this generally means a couple of days of lab testing. \$\endgroup\$ – Andrew Oct 17 '16 at 12:52
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Yes, there are.

DMX sounds alarm bells: That sounds like switching "heavy" loads or dimming things – and that sounds like you can easily incur EMI problems.

Now, for devices you don't sell that aren't meant to transmit radio signals, you don't need to FCC/OFCOM/BNetzA...-certify them. However, you, and all the devices you own, are subject to regulation on electromagnetic emissions. If your dimmer happens to transmit strong interference where it is not allowed to (i.e. anywhere in the spectrum, but with varying limits), you're breaking the law. Now, you can avoid that usually by proper shielding of the switching components.

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  • \$\begingroup\$ Selling interference sources would clearly be breaking the law. Using them? More like a civil matter. Even radio hams, building intentional emitters, aren't expected to submit products for compliance testing. But if a neighbour complains to OFCOM about lousy TV reception, you are expected to diagnose and fix the problem, or failing that, cease transmitting. \$\endgroup\$ – Brian Drummond Oct 17 '16 at 12:33
  • \$\begingroup\$ unlawful emission == breaking the law == illegal != criminal, and that's a good thing \$\endgroup\$ – Marcus Müller Oct 17 '16 at 12:37
  • \$\begingroup\$ @BrianDrummond also, notice that you actually need a ham license to be allowed to do that. \$\endgroup\$ – Marcus Müller Oct 17 '16 at 12:37
  • \$\begingroup\$ Good points. Different ham bands have different (more or less strict) license requirements ... I can't remember but don't some bands have minimal to none requirements other than actually applying for a license? \$\endgroup\$ – Brian Drummond Oct 17 '16 at 12:41

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