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Discuss Question about 'self made' 12V Lighting in new extension in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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Straight up, I'm not an electrician. I'm an electronics engineer. I currently have a range of LED products on the market and my commercial lighting designs have been in continuous production since the 1990's. I'm having an extension built and naturally see it as a great way to showcase my latest products.

Now my building contractor is telling me that I can't install my own colour lighting, which I had planned to first-fix any day now. My installation would involve a 12V 10A double insulated switch-mode supply connected via a Fused Connection Unit to an existing lighting circuit that was put in specially for my lounge lighting (also self designed) when we moved into our house 20 years ago. From there would run a short DC twin cable to the controller then a multicore cable out to the assorted lighting devices. These consist of 10m of LED tape and a group of downlighter-like fittings (3D printed).

I've been reading Part P of building regulations trying to understand the process but the clock is counting down to when the contractors electrician arrives so I thought I would seek expert knowledge on these forums in a bid to arrive at a speedier conclusion.
 
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Can't see why you can't install that.

You don't need a fused connection unit. They are not used or required on lighting circuits which are adequately fused anyway.
 

telectrix

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absolutely no reason for you not to install the lighting. at a push you could leave the final connection into the house wiring to the electrician.
 
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Thanks for the replies so far. I think the problem might be to do with certification. There are other electrical installation works being undertaken by his registered fitter and the lighting I wanted to install would seem to have to be included in his certification.
As long as the work you do complies with the regulations you can do it.
For electrically isolated 12V circuits the only conceivable hazard would be sharp edges or tripping. Seriously though, I appreciate that Part P is about safety, referring to the standards set out in BS7671
From what I can see hazards to be considered are the potential for fire caused by short-circuit I2R heating in conductors (electronic current limiting in the AC-DC converter being the remedy in my case), separation of low and high voltage cables (my LV is distributed in its own PVC conduit). Other than that I don't see any other issues. Am I missing any others?
 
Surely the electrician on site can do the install to your specifications. The main contractor doesn't want to take responsibility by the sounds of it. Or ask the electrician to sign off your work once it's been inspected.
 
Part P is very 'broad brush'
"Reasonable provision shall be made in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installation from fire or injury."
This is usually demonstrated by compliance to the current edition of BS7671.

Your lighting scheme sounds easy to sign-off, the lighting itself is SELV so..
1) The PSU should be connected by properly protected wiring, your arrangement sounds fine.
2) The PSU should provide adequate creepage and clearance to avoid exposing the SELV side to mains. It should have a CE label and you can take that certification to assure insulation.
3) To be thorough, before energising the circuits, confirm that the supply insulation resistance is at least 500k ohms with 250V DC applied. (Table 64 of BS7671 18th edn).

Your contractor just doesn't fancy the job so the advice here to get a competent electrician to fit and sign it off is sound. If in doubt talk to your building control officer.
 

telectrix

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and put the builder's shovel to it's designed use. bash him on the head with it. :D:D:D.
 

davesparks

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Thanks for the replies so far. I think the problem might be to do with certification. There are other electrical installation works being undertaken by his registered fitter and the lighting I wanted to install would seem to have to be included in his certification.

For electrically isolated 12V circuits the only conceivable hazard would be sharp edges or tripping. Seriously though, I appreciate that Part P is about safety, referring to the standards set out in BS7671
From what I can see hazards to be considered are the potential for fire caused by short-circuit I2R heating in conductors (electronic current limiting in the AC-DC converter being the remedy in my case), separation of low and high voltage cables (my LV is distributed in its own PVC conduit). Other than that I don't see any other issues. Am I missing any others?
There is no need to include your work on their certificate, your work will be covered by the bs7671 certificate you issue when you complete it.

BS7671 applies to installations at LV and ELV, so basically if it is below 1000V AC or 1500V DC it applies.

There are specific requirements in bs7671 applying to elv lighting, I can't remember the details off the top of my head as I don't deal with it regularly.
 
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There is no need to include your work on their certificate, your work will be covered by the bs7671 certificate you issue when you complete it.
That's where my confusion comes in. Certification schemes - IET Electrical - https://electrical.------.org/bs-7671/building-regulations/part-p-england-and-wales/certification-schemes/ says:
Persons who are not registered with a self-certification scheme - including DIYers - will need to notify or submit plans to a Building Control Body (BCB), unless the work is non-notifiable.
So, as a DIYer doing non-notifiable installation work, I interpreted this as meaning I don't need to interact with building control at all.

Yet you say I will issue a BS7671 certificate. I'm sorry to say none of this makes any sense to me. In trying to find out how a "DIY'er" might go about issuing such a certificate, I checked the Institution of Engineering and Technology for details of self-certification schemes. This lead me to download the IET-BCA Guidance document - the content of which would undoubtedly lead BC to view me as maximum risk (having no modern Electrically related qualifications).

What's getting my fur up is that after 44 years of experience in the electronics industry I'm more than capable of producing electrical and electronic designs that go through test houses and receive CE certification covering all aspects of safety, allowing said designs to be mass-produced and put into international markets - yet from what I see, I would have to jump through hoops to convince Building Control that I should be allowed to screw a bunch of these 12V circuit boards to my ceiling without paying them to come and prod about in my own home. Pardon me, but my blood is beginning to boil here.
 

Matthewd29

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It is what it is, your an electronic engineer and not an electrician so you can't issue the certificates. Also there is no formal qualification for issuing the certificate you just have to be 'competent'. Personally I wouldn't get involved in certifying any DIY work whatsoever and never will but at the end of the day it is your house and if you feel you are competent to do the job then you can go ahead and do it . I suspect the contractor is taking the same point of view as me and doesn't want to take any responsibility for it and I understand that
 
That's where my confusion comes in. Certification schemes - IET Electrical - https://electrical.------.org/bs-7671/building-regulations/part-p-england-and-wales/certification-schemes/ says:

So, as a DIYer doing non-notifiable installation work, I interpreted this as meaning I don't need to interact with building control at all.

Yet you say I will issue a BS7671 certificate. I'm sorry to say none of this makes any sense to me. In trying to find out how a "DIY'er" might go about issuing such a certificate, I checked the Institution of Engineering and Technology for details of self-certification schemes. This lead me to download the IET-BCA Guidance document - the content of which would undoubtedly lead BC to view me as maximum risk (having no modern Electrically related qualifications).

What's getting my fur up is that after 44 years of experience in the electronics industry I'm more than capable of producing electrical and electronic designs that go through test houses and receive CE certification covering all aspects of safety, allowing said designs to be mass-produced and put into international markets - yet from what I see, I would have to jump through hoops to convince Building Control that I should be allowed to screw a bunch of these 12V circuit boards to my ceiling without paying them to come and prod about in my own home. Pardon me, but my blood is beginning to boil here.
I'm also an electronics engineer and a little behind you with only 42 years experience and understand your concern, but you may be overthinking this one a bit.

Part P doesn't require any particular qualifications, it only requires 'competence', if you can convince your building inspector that you understand BS7671 and have the practical skills and experience to do a compliant installation, you're free to do the work, document it and submit to whatever checks are specified. In practice that doesn't work well for two reasons, 1) you have to become and stay current with technical guidance and practice, which realistically few electronics engineers will do, and 2) Building Control will charge a full fee for processing the certification. They may also refuse to go that way.

An electrician does a whole bunch of training to acquire and maintain the specific technical skills to install and validate safe power distribution and for an annual fee to a certifying body, is permitted to sign-off work as compliant without the whole Building Control route. This is almost always the safest and most cost-effective route.

You just need a 12V supply for your LEDs and that shouldn't be any problem, the contractor you mention in your original post has it wrong. In the extreme you could have a 13A socket wired in (or FSU if you prefer) and you can connect any CE labelled PSU into it and do whatever you like with the 12V coming out. Anything less than 60V is not of interest. 60V always sounds a bit high for strict electrical safety but it arose because the telephone companies didn't want their voltages to be classed as hazardous live, hence 60V.

By your contractors logic a train set, Scalextric and Christmas lights all need Part P certification - fortunately they don't, it would be a bit of a downer on Christmas Day if they did
 

davesparks

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That's where my confusion comes in. Certification schemes - IET Electrical - https://electrical.------.org/bs-7671/building-regulations/part-p-england-and-wales/certification-schemes/ says:

So, as a DIYer doing non-notifiable installation work, I interpreted this as meaning I don't need to interact with building control at all.

Yet you say I will issue a BS7671 certificate. I'm sorry to say none of this makes any sense to me. In trying to find out how a "DIY'er" might go about issuing such a certificate, I checked the Institution of Engineering and Technology for details of self-certification schemes. This lead me to download the IET-BCA Guidance document - the content of which would undoubtedly lead BC to view me as maximum risk (having no modern Electrically related qualifications).

What's getting my fur up is that after 44 years of experience in the electronics industry I'm more than capable of producing electrical and electronic designs that go through test houses and receive CE certification covering all aspects of safety, allowing said designs to be mass-produced and put into international markets - yet from what I see, I would have to jump through hoops to convince Building Control that I should be allowed to screw a bunch of these 12V circuit boards to my ceiling without paying them to come and prod about in my own home. Pardon me, but my blood is beginning to boil here.
You are confusing bs7671 with part P, they are two seperate things. The work will not be notifiable for the purposes of part P. But it is electrical work covered by bs7671 so you shoukd be issuing the appropriate certificate.
 
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You just need a 12V supply for your LEDs and that shouldn't be any problem, the contractor you mention in your original post has it wrong. In the extreme you could have a 13A socket wired in (or FSU if you prefer) and you can connect any CE labelled PSU into it and do whatever you like with the 12V coming out. Anything less than 60V is not of interest. 60V always sounds a bit high for strict electrical safety but it arose because the telephone companies didn't want their voltages to be classed as hazardous live, hence 60V.

By your contractors logic a train set, Scalextric and Christmas lights all need Part P certification - fortunately they don't, it would be a bit of a downer on Christmas Day if they did
But isn't it the case that if I were to build those Christmas lights into a wall or ceiling, and was doing this in parallel with a scheme electrician installing 240V wiring into the same room, then he would be compelled to make reference to said xmas lights regarding all applicable aspects of BS7671? Let's look at its scope in a minute...

You are confusing bs7671 with part P, they are two seperate things. The work will not be notifiable for the purposes of part P. But it is electrical work covered by bs7671 so you shoukd be issuing the appropriate certificate.
Yes, but this seems to contradict Shoei's reply above.

...BS7671 defines the scope of its applicability in 110.1.2 as being "Circuits supplied by nominal voltages up to and including 1000V AC or 1500V DC" expressly including "fixed wiring for information and communication technology, signalling, control and the like" i.e. any wire (even if not in circuit apparently! A certificate would seem to be required for a dead loop of wire clipped to a joist.o_O ).

I can't emphasise enough how I'm not trying to withhold due payment to any scheme member to save a few quid by doing something myself, but it's simply not practical to train and instruct the contractor to assemble my electronic components. For example, the scope of BS7671 takes in something as simple as the DHT22 temperature/humidity sensor I was going to cable-up into the roof space for connection to the Raspberry Pi that manages my Home Control system.

Over the years, as millions of other people must have, I've pulled aerial, speaker, ethernet, intercom, telephone etc. cables through walls, floors and ceilings and only wished I had been able to do so at 1st fix! Yet as these 'circuits' are all in scope, then should we be lucky enough to have the opportunity to install them at 1st fix, they apparently require a certificate that most of you agree is impractical for a non-registered individual to issue. Maybe the Bureaucrats have won this extra ground for scheme members but beyond the trivial IT systems mentioned, there are electronics hobbyists and professionals who would appear to have become ensnared in a world they have no moral need to be involved with.

Now I'm not here to seek an audience for a rant, but to poll scheme members for thoughts on how they would go about working with an electronics hobbyist/professional who views their 1st fix shell as an "equipment case" for their own circuit boards. I get how the problem hinges around the inspection and sign-off and how naturally cautious a scheme member would be about come-back if something stupid went down after they left.
 
I’m thinking that perhaps it’s a case that there no BS for your new equipment (yet) and the sparks will only fit BS marked items, this is sensible given some of the shite customers provide from China, eBay or both. New and modern tech could be fitted as a departure - you would need to convince the spark that they are safe because this would be documented in the departure. Just a thought, don’t beat me!
 
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