Running cable to attic lights and smoke detector

[gotnolegs]

Hi

I am running cable in the upper floors of the house at the minute, i wont be getting them connected and signed off till after the new year so i have no sparky to consult. I have worked for a couple for sparkies in the past but i am a bit rusty on the regs (plus one was a bit of a cowboy and didnt care).

At last count i can only run cables through a wall within 150mm of a corner or horizontal/vertical from a fitting. Is this still correct?

I fitted single 25 mm round conduit behind the plaster board running up to a 35mm knockout (dimable light switch) and again out of the top of it running to the corner of the ceiling (which then follows up to the ridge).

I now want to fit smoke detectors so i can rent the house out in the future.

Can i run the additional wiring for the smoke detector through the same conduit? It will mean running the cable through the same knockout box as the switch to reach the terminal box under the floor, this is what i am unsure of.

I will be rigging the smokes to the light circuit. I have seen it done [passing extra cables through a knockout] but unsure if it conforms to the regs. If it is fine, is the box deep enough for the extra cable to pass through and a dimmer? If not i am going to have problems geeting the cable up there within safe zones.

Also the light circuit will be a 3 way switch, from memory i had planned for 2x 1.5 mm cables to be running from the floor to the switch and 1x 1.5 to be running from the switch to ceiling. Is the conduit big enough to take the additional cable for the smoke detector or will i have to use oversized cables for thermal reasons?

I really want to avoid the sparky being uncomfortable with the way i have done things when it comes to 2nd fitting and signing off, the last thing i want is to be having to change things (i am going to plaster this winter).

Cheers

EDIT: since i cannot lay cables unsupervised/not employed by the sparky signing off i will get a sparky to do that. However, i still want to keep the cost down so will be using my own channels and conduit, so the question still stands. No attempt has actually been made to answer the question yet.

 

[bernardgreen]

When running cables to supply lamp(s) in the loft consider running them to the ground floor lighting supply and NOT to the supply for the lights on the floor below the loft access hatch. This enables you to have lights in the loft when working of the lights for the floor below. It also means that in the event of losing one lighting circuit there is still light either below or above the access hatch allowing a reasonably safe exit from the loft.

 

[gotnolegs]

I was rigging the attic light + smoke on it's own shared circuit even though it is only gonna have one spot rail (so i could have each floor on a seprate trip switch at the box).

 

[bernardgreen]

They should be on different RCDs if not RCBOs.

 

[gotnolegs]

What should be on seperate rcd [assuming the sparky does not use RCBO]? Lighting on each floor or the smokes?

I am not sure what goes on at the box, i used to knock channels and run cables following the sparkies instruction, not mess around with boxes (so i have little idea what must happen there).

AFAIK what i was planning is fine, run cable up the the attic from consumer for lights [and lay the circuit], run cable up from consumer to the attic for sockets [and lay the ring circuit], run cable from smokes to terminal box on attic light circuit. Repeat for each floor. Let the sparky decide what gets protected by what at the box and just tell him i want each floor seperate in case something breaks.

 

[ban-all-sheds]

How will the electrician know the exact route the cables have taken?

How will he verify the installation method used, grouping factors etc, to calculate the current carrying capacity of the cables?

How will he confirm that the same size of cable has been used throughout each circuit?

How will he confirm that there are no concealed joins?

How will he check for things like support, bend radii, damage to cables?

 

[gotnolegs]

"How will the electrician know the exact route the cables have taken?"

Gonna photo the channels before i plaster for anything recent and have already done it for the conduit that is covered. The floor hatches will still be accessible so confirming it will be common sense tbh. Plus i have a metal detector so he can verify they are where i say they are if any doubt and i am sure he will too. He will have to 2nd fit so remember he is going to have goood access to most of it aside the walls.


"How will he verify the installation method used, grouping factors etc, to calculate the current carrying capacity of the cables?"

Installation under the floor will be obvious, as will the round conduit atttched to the knockout boxes.

The house is small,, the circuit is going to be small and basic, 1.5's for lights and 2.5's for the ring is more than ample unless thermal emissivity is at play (which is one of my questions that i asked where a conduit could potentially be over packed). Never seen a sparky use bigger cable sizes than this even on circuits that are supping far more power except whetre covered in insulation.


"How will he confirm that the same size of cable has been used throughout each circuit?"

Well he is going to be connecting them at each fitting, so unless he presumes i joined thinner wires on within the walls to save money (while i will probably have spools of wire spare) it would be a bit of a leap to presume otherwise. TBH if they suggested that i would hire a smarter sparky... they could test the cable with a meter to verify the resistance against the estimated cable lengths, obviously.


"How will he confirm that there are no concealed joins?"

If they are going to assume i have joined cables within the walls when i will have spools of excess cable running around frankly i will hire someone else. However, if they had such reservations, since i already said i have run 25 mm round conduit behind the plasterboard i could obviously pull it out and show them in most places. Sure there will be one or two areas where this would be tricky but sparkies here are not exactly swimming in work so i will find someone reasonable.


"How will he check for things like support, bend radii, damage to cables?"

They can look under the floor through the hatches; same as above if they wanted to visibly check what was in the walls, but i wouldn't hire someone silly enough to think i would not use safe materials in a house i was going to live in..

The way you are speaking is as if it is unheard of for people to run their own cable and impossible to verify it, neither are true If the sparky wants the job, they will have their methods for assessing if i cut corners. If they dont want it, they can give the third degree and get the door


Anyway, back on track, can anyone please answer my question? All i want to know is in post #1. The rest is my concern It would be great if you could take the minute to help me with that.

 

[skotl]

You're about to incur the wrath of ban-all-sheds (and others)...

Anyway, you just said that you would ... "use safe materials in a house you were going to live in". But in your original post, you mentioned renting it out...

The regulations are in place for a reason, primarily for your safety and others who are in the house, and you really shouldn't be looking for ways to cut corners.
The additional liability if you intend to rent the place out makes the situation even more critical. What if there was a fire that injured your tenants (or worse) and it was traced back to your wiring?

You've said you'll engage an electrician, which is half the battle, but you should engage him now rather than at the end. It's not worth the risk for the sake of an extra couple of hundred quid.

 

[gotnolegs]

Aye, rent it out in the distant future. That is only potentially too.


I have not said i am trying to cut corners at all, where did i say that? I have directly said otherwise actually Save money on installation, yes, cut corners, no. Everything i intend to do that i have not asked or have done already is within regulations and i can prove to the sparky, what i am unsure of i have asked...


I would engage a sparky now but tbh i am not doing the entire house now, i just want to get the attic in plaster so that i can live in there and tackle the rest of the house (at which stage the sparky will come in). The attic is one room, only a part of it won't be visible for him to see. That is fairly minor. I wont be doing the rest of the house untl next summer as i have other commitments..


If ban all shed feels like giving the the n'th degree for that reply then so be it, it was a fair reply it just sounds stern in text (sorry if it came cross otherwise). That is why i slipped smileys all over the spot. TBH i could have put more detail on post #1 to avoid all the questions but when i write posts with loads of detail people skim them so i cant win..

Plus tbh it really isn't anyones business what process i take with getting the sparky in (no offence meant at all) they are either willing to confirm that i can run a cable through a knockout and if i plan to put too many cable in a 25mm conduit or they are not. People seem happy to tell people how to do stuff on here that clearly have no intention of getting a sparky to sign off so i don't see the problem here. Whoever i hire will question me himself no doubt


Sure i have no idea what goes on at the board but a little advice to someone who has laid a good few cables for proper sparkies really that bad?


I appreciate the concern and all, please remember i am not intending to be rude to anyone i just dont come across well in text form

 

[gotnolegs]

Yea i just re read it and my wording does sound a little rude if, it aint meant to be though so please bear that in mind.

Hopefully though it does not get taken the wrong way, plus i have now clarified some points that may be of concern to people.

 

[ban-all-sheds]

Firstly this work is notifiable, i.e. it needs Building Regulations approval. You have to apply for that before you start, and as part of that tell them how you will comply with Part P.

If you think that you will get an electrician in after the event, and present him with your faits accomplis in the aspects of design and construction, and expect him to say that he did it all and it all complied with the Building Regulations then prepare to be disappointed.

Secondly there is the matter of the Electrical Installation Certificate.

With a couple of key words highlighted:

I being the person responsible for the design, construction, inspection & testing of the electrical installation (as indicated by my signature below), particulars of which are described above, having exercised reasonable skill and care when carrying out the design, construction, inspection & testing hereby CERTIFY that the said work for which I have been responsible is to the best of my knowledge and belief in accordance with BS 7671:2008, amended to 2011 except for the departures, if any, detailed as follows:

It is feasible for an electrician to take the view that if you are closely under his direction and supervision, he can take responsibility for those aspects even if you are the one who physically installs the cables.

It is not realistic to expect him to say that he was the person responsible and he exercised reasonable skill and care and to the best of his knowledge and belief what he did was OK if not only did he not do it, but he had no hand in it whatsoever - it was done by you some months before and now you are asking him to certify it.

You may wonder how could anybody with any sense think you might have cut corners or made mistakes etc, but the guy's professional reputation and membership of a Competent Person scheme will be on the line.

Get an electrician on board now.

 

[gotnolegs]

I am full well allowed to lay cable. I just cannot connect it without building approval. A sparky will decide if it is correct and if he is willing to sign it off for part p, if they are not happy that is up to them. I do not need to open a ticket to lay cable so long as i dont tamper with the existing circuit or attempt to install it.. I even confirmed this with a sparky who i was working with last year who was willing to come and second fit (i dont know but that offer may even still stand).


I don't expect anything from anyone, if he is not satisfied with the section of cable he cannot check he is free to leave. If it is a small section i will pull it out. Truly, i do not think they are under any obligation to do anything, they have an option, if they re not satisfied i understand that is my risk that i may have to pull the cables out of the conduit or make a minor alteration.


I am only talking about the attic here, the rest he will be able advise on in summer. I am literally talking about plastering over one 3 meter section of cable that can be pulled back out of the conduit and laying cable through the floor joists for a basic ring main, which he will have full physical access to..


Really, i left a lot of blanks open but i had to to get my post read, if i put everything i could think of in post #1 nobody would bother to read it


If they are not comfortable with it i am 100% sure they will not put their name to it. I am sure you know yourself that what is in the floor can be checked or easily redone without waste and that a 3m section of cable in the wall while inconvenient to remove can be removed and refitted into 20mm conduit should the person i hire wish it.


What would not be so easy is if it turns out i need more conduit for thermal emissivity reasons or to find another route for the smoke detector, which is why i am here asking that specific question.


Now i have given proper detail and context into what i have planned and what i mean to do i hope this might alleviate the hesitation to answer what i ask. I really have no expectation of any sparky to do anything for me, i understand they may want the section the cannot see removed and redone (this is one reason i used 20mm round conduit everywhere, i even fitted it under the floor already so cable can easily be slipped in and out of it).


NOTE: post 1 was meant to say the wall has 20mm round conduit, not 25mm.

 

[gotnolegs]

Just to clarify this is the only part that will not be visible, the red is 20mm conduit which can easily have cable pulled out again.

Everything i plan to run under the floor is very easy for him to inspect as i have put plenty of access hatches (one at every fitting or terminal) with round conduit between so he can request i pull it out to check for damage and slip it back in..

Cable can be fed in and out easily for inspection with round conduit, there are no sharp turns.

Untitled

• gotnolegs
• 29 Oct 2014
• 1

1st floor and ground floor will be done after i can pay a sparky to start in summer. I just need to get the one room in plaster so i have a decent room to live in while the rest of the house is ripped apart.

 

[ban-all-sheds]

I am full well allowed to lay cable. I just cannot connect it without building approval. I do not need to open a ticket to lay cable so long as i dont tamper with the existinf circuit or attempt to install it..

Laying cable is installing it. It doesn't have to be finally connected or energised for the process of installation to have started

Choosing the cables to install, and where to install them, is design.

P1 Reasonable provision shall be made in the design and installation of electrical installations in order to protect persons operating, maintaining or altering the installations from fire or injury.

So that makes what you are doing a controlled act within the scope of the Building Regulations, and because of the details of what you are doing it is notifiable.

So yes - you do need approval to do what you are doing, whether you like it or not.

I even confirmed this with a sparky who i was working with last year who was willing to come and second fit

He was wrong.

And if he's the sort of dishonest person who is prepared to take a payment from you in order to lie to his scheme organiser and to Building Control about what he did then you should think carefully about whether you should have anything to do with him. If he'll lie to them, he'll just as happily lie to you.

 

[gotnolegs]

To be honest the guy i asked was a very good and professional electrician, perhaps he just had trust in my work and was willing to do it because i was already working under him at the time and doing exactly that. The cowboy i mentioned in post 1 i would not let near my house with a 10ft pole..


If you are certain that is the case i will contact my local council and confirm it.


However, surely i can fit my own conduit for the cable to be fed through and plaster over it.. I can't get a sparky until next summer so am i good to fit the conduit, plaster it and get a sparky to feed it through afterwards?

If so i would like to get the conduit in and plaster over it so i have a decent room for now. This should surely circumvent any practical or legal issues and allow me to acheive a temporary living space.