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.
 
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.
 

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!
 

davesparks

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they apparently require a certificate that most of you agree is impractical for a non-registered individual to issue.
Who said its impractical for a non-registered person to certify work to bs7671? There must be hundreds of us who aren't registered with any scheme but still certify our work.
 

Lucien Nunes

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Good contractors would only install material for which they had, or could reliably obtain, traceable approvals. In the event of any comeback, their position is clear regarding the boundary between their responisibilities and those of the manufacturer. If your equipment is CE-marked, it doesn't matter that you made it, you can ask him to install it and his responsibilities are unchanged. Some contractors will however balk at fitting items that they consider less satisfactory than their normal choice. If your equipment does not carry the necessary approvals, e.g. because it's a prototype or demo model, then a contractor might not want to install it.

If you want to install equipment for the supply of electrical energy yourself, then it might need to comply with BS7671. A micropower sensor cable would not, an ELV circuit carrying 10A to lighting fixtures certainly would. The onus will be on you to provide the certification that it does. This should be no problem for you, as you will understand the requirements and can fill in the certificate. However, some would consider the load side of an un-pluggable CE-marked PSU brick not to be part of the fixed installation. If that is in fact the case, then once the electrician has laid on the supply to the brick, you can do whatever you like as far as BS7671 is concerned.
 
Good contractors would only install material for which they had, or could reliably obtain, traceable approvals. In the event of any comeback, their position is clear regarding the boundary between their responisibilities and those of the manufacturer. If your equipment is CE-marked, it doesn't matter that you made it, you can ask him to install it and his responsibilities are unchanged. Some contractors will however balk at fitting items that they consider less satisfactory than their normal choice. If your equipment does not carry the necessary approvals, e.g. because it's a prototype or demo model, then a contractor might not want to install it.

If you want to install equipment for the supply of electrical energy yourself, then it might need to comply with BS7671. A micropower sensor cable would not, an ELV circuit carrying 10A to lighting fixtures certainly would. The onus will be on you to provide the certification that it does. This should be no problem for you, as you will understand the requirements and can fill in the certificate. However, some would consider the load side of an un-pluggable CE-marked PSU brick not to be part of the fixed installation. If that is in fact the case, then once the electrician has laid on the supply to the brick, you can do whatever you like as far as BS7671 is concerned.
This is an excellent reply - well stated. The only comment I have is whether the OP is in fact the manufacturer, I believe he is and as stated the boundary is clear. Placed in this position consideration would need to be in obtaining appropriate documentation from the 'manufacturer' and detail this in the departures section of the certification and limited as a 'PSU brick'. or some such technical jargon.
 
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Good contractors would only install material for which they had, or could reliably obtain, traceable approvals. In the event of any comeback, their position is clear regarding the boundary between their responisibilities and those of the manufacturer. If your equipment is CE-marked, it doesn't matter that you made it, you can ask him to install it and his responsibilities are unchanged. Some contractors will however balk at fitting items that they consider less satisfactory than their normal choice. If your equipment does not carry the necessary approvals, e.g. because it's a prototype or demo model, then a contractor might not want to install it.
Totally understandable. I really don't wish for the contractor to install any of it. It would be trivial work for me compared to explaining how it would be done by someone else anyway. The problem seems to be with having me do some installation alongside theirs when it comes to any third-party inspection.
Lucien Nunes said:
If you want to install equipment for the supply of electrical energy yourself, then it might need to comply with BS7671. A micropower sensor cable would not, an ELV circuit carrying 10A to lighting fixtures certainly would. The onus will be on you to provide the certification that it does. This should be no problem for you, as you will understand the requirements and can fill in the certificate. However, some would consider the load side of an un-pluggable CE-marked PSU brick not to be part of the fixed installation. If that is in fact the case, then once the electrician has laid on the supply to the brick, you can do whatever you like as far as BS7671 is concerned.
While I was going to power the AC-DC power supply from the lighting circuit (simply because I have a dedicated MCB for the zone containing my own products) I can simply plug-in to an existing 13A outlet in the rack cupboard where the rest of the home-control kit lives.

But you only say some would consider the lights so connected not to be part of a fixed installation. I see nowhere in BS7671 that covers this edge case so I would have nothing in writing to demonstrate this to the contractor.

As for a micropower sensor cable, would it not come within the scope of BS7671 where 100.1.2 describes "fixed wiring for information and communication technology, signalling, control and the like"? The keyword seems to be "fixed wiring" - evidently of any description.
 
There is a 60 page IET Code of Practice for Low and ELV DC power distribution in Buildings. I have version 1, published in 2015.

ELV is defined as not exceeding 50 volts AC or 120 volts ripple-free DC (in BS7671). You do need to meet BS7671 as regards to current carrying capacity of the wires, etc, etc, but not any building Regs. as far as I could find out.

Video resources for LV and ELV d.c. power distribution - https://electrical.------.org/wiring-matters/issues/61/video-resources-for-lv-and-elv-dc-power-distribution/

In your case I would get the work signed off without your DC lighting and then add it if afterwards. I can understand a normal sparky being wary of signing off your bits. That is what I did in my own house - in Scotland you have to be a Member of a competent group (e.g. NICEIC et etc) and also on a list of Approved Electricians in Edinburgh to meet the Scottish equivalent of Part P Building Regs. But the ELV DC wiring and fitments do not, as far as I can find out, come under the building Regs.
 
Install your bit yourself and ask the contractor to clearly state in his installation certificate the extent of the installation the certificate covers. Which would be a case of identifying the circuit excluding ELV lighting.
 
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The first fix is underway and I will be laying in draw-wires to key locations enabling me to install most of my equipment at a later date without too much surgery.

I greatly appreciate the constructive and civil atmosphere of these forums. This is in contrast to some other online trade forums I have visited. Thank you all for taking time to consider my question.
 

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