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Discuss 12v downlights - help required in the Commercial Electrical Advice area at ElectriciansForums.net

D

DonaldJ

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Afternoon all,

I'm new here and this is my first post.

I recently posted on another forum with a rather long post about a problem in my shower and utility room although I haven't had much of a response. Probably a combination of a long post and me not explaining myself properly.

Basically, whoever did the wiring bodged it good and proper and the lighting is on a radial (which incidentally is protected by a 32a MCB!) rather than a lighting circuit.

I desperately need to make it safe and am unable to afford professional help at the moment so have no option but to rectify it myself.

I've disconnected the lighting from the radial completely now and now need to re-insall the lighting circuit.

What I'd like to know is can I take the supply for the lights and fan from the load side of an FCU fused at 3a and then just treat this as a standard lighting circuit? At the moment the fan is connected to a switch of its own in the back of a 2g switch. Can I just connect this to the lighting circuit at a junction box so that the fan operates whenever the light is switched on? The wiring from the fan to the switch is simply a flex which is concealed in a stud all. I though that the flex should be connected to a flex outlet, with tin and earth suplying the outlet.

Any advice would be much appreciated as the wiring was in a dangerous state and is in need of fixing so I can use the utility room once again.

For info, I've pasted the long post below if you really want to spend a week reading it.

Thanks in advance for any helo you may be able to provide.

Don.

Original (long) post in another forum.

My apologies for the very long post but I figured it best to try my best to describe the situation as fully as possible so I can hopefully make it clear enough to get the best advice possible.

I need a bit of help with the electrics in my house. I bought a house a couple of years ago which had what appeared to be a nice kitchen refurbishment and a garage conversion into a utility room and shower room.

For a while now the downlights in the kitchen have been switching off and on intermittently. The main problem though is the shower room and utility room. I had the light on the other day in the shower room and the room started to smell of smoke. Obviously I switched the lights off and haven't used them since.

Above the shower is a 240 downlight, which is connected to the circuit by a terminal block and taped with insulation tape. From the terminal block there is a cable going to a transformer, again connected by a terminal block, the other side of which is a thin (ish) black flex that goes on to two 12v downlights. Having pulled these lights out and inspected the terminal blocks, the cable has melted near the blocks and the blocks and tape are extremely brittle and dry. Obviously these have been overheating.

I should also point out that there is a fan in the shower room and is controlled by the other switch on the 2g switchplate. I was a bit suspicious of how the fan and lights were wired when I tried isolating the circuit. The lighting circuit was isolated when I swithed off the utility room ring main. Upon removing the switchplate my suspicions were confirmed when I found two 2.5mm live conductors in one terminal of the switch controlling the fan and the live conductor of the fan FLEX in the other. Surely the flex should be connected to a FCU. The neutral is connected ina terminal block to the neutral of the ring.

I haven't as yet investigated so far as to exactly where the lighting gets its power but suffice to say it's somewhere off the ring main but I can only see the the connections in the back of the switch.

Now I need to get this fixed - obviously. It's currently dangerous. However, I have no money at the moment and can't afford an electrician. I am however familiar with electrics an prior to 2005 had in the past re-wired my old house successfully so do have a bit of knowlege. Having said that, I am not an electrician and do not have access to the test equipment and full knowlege that professional electricians have.

First question is, if I was to fix this myself, does this fall under Part P and would it therefore be notifiable (£180 notice fee to my BCO I believe!)? If it were a straight like for like replacement then possibly not but given that I'm going to have to remove the lights and fan off the ring main and connect to (or create a new - there is a spare way in the CU) lighting circuit then possibly so, especially given that it's in a shower room. If it's notifiable then I'm a bit stuck due to the money situation but will have to make it safe anyway.

My net question is how I really go about fixing it. I'm going to have to remove the lights and fan from the ring main and join the ring main together with terminal blocks and choc box and leave behind a blanking plate where the current switch is (the switch is in the utility room by the way, not in the shower room). I'm then going to have to fit a new switch elsewhere. That's fine. However, what I am unsure of is the best way of replacing the lights.

I don't really like LV lighting but I think I'm going to have to use it. Obviously the first step is to disconnect everything to do with the lights and fan from the ring. So far so good. However, it's here 'm a little stuck. Is installing a LV lighting circuit exactly the same principle as a loop in lighting circuit or would it be better to use a JB circuit?

I was planning on replacing the shower light with a LV shower light (this is all I can find on Screwfix anyway and comes pre-assembled with transformer and junction box etc) and then fitting two LV lights in place of the two current ones, each with their own transformer. The shower light JB would be fed with 1.5mm cable to the JB which would then in turn feed another JB for the first LV light in the chain with 1.5mm cable which again in turn would feed the second LV light in the chain with 1.5mm cable. From each JB would be the supply flex to the transformer for each light.

My other problem here is the melting of the existing connections. I suspect a combination of poor connections, inadequate cable / flex between transformer and light fittings and also the fact that there's insulation in the ceiling space too. There are no fire hoods either. I'm aware that reducing voltage increases amps which has generated more heat than the cables or flex can cope with, especially given that the connections and transformer sat below insulation. Do I remove as much of the insulation as I can before I start? I'll also fit fire hoods although as the room used to be a garage, there is a secondary ceiling above the ceiling into which the lights are fitted. I assume the transformers and connections sit outside the fire hoods.

I am also now worried about the utility room lighting (this is also connected to the ring main) so will probably have to sort that out too. there are 5 LV downlights here all powered it seems from one transformer between switch and first light in the sequence. Does the same apply to this. 1.5mm cable daisy chaining to 5 junction boxes, each JB feeding a transformer for the light?

My other concern is now obviously for the kitchen lighing. The kitchen refurb was done at the same time as the utility and shower room so it's reasonable to assume that the quality of this install is just as poor. Is this the reason why the bulbs go off and on - they overheat and switch off until cool enough?

I appreciate that this work may fall under Part P but with my current financial situation I am going to struggle to afford to do this work myself, let alone pay to notify or to pay a qualified electrician to do it. I would therefore like to do it now (in any event it will be safer than it currently is) and would be extremely grateful for any advice you folks can give.

If necesary, I will have the whole thing re-done by a registered eectrician when I can afford to do so but that's likely to be a couple of years away at least.

Thanks in advance for any advice offered and once again, sorry for the length of the post.
 
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W

wayne

  • Thread Starter Thread Starter
  • #2
check the cable size off of the mcb minimum should be 6mm
is all you planning to do ;wire from the sw fu spur to a sw to the lights and the fan?
please answer briefly (yes,but....not quite...)
 
D

DonaldJ

  • Thread Starter Thread Starter
  • #3
check the cable size off of the mcb minimum should be 6mm
is all you planning to do ;wire from the sw fu spur to a sw to the lights and the fan?
please answer briefly (yes,but....not quite...)
Cheers for the reply Wayne.

Cable of MCB is 2.5mm. It's a radial so I was planning on changing MCB to 16a.

Sort of yes. Was planning on an unsw FCU, with 1.5mm t&e to a junction box to create the lighting and fan circuit.

Was going to go into more detail but will leave it that brief for now (as per your instruction).

Regards

Don
 

Had8Lives

-
Arms
What you are planning seems reasonable. Looks like the previous owner was either a rubbish DIY'er or had dodgy tradesmen in. Lights over showers should always be IP rated and LV.
 
W

wayne

  • Thread Starter Thread Starter
  • #5
how are you planning to switch it on/off ,locally at the room ?
keeping it brief works sparks have short memory spans ......now where was i going?
 
D

DonaldJ

  • Thread Starter Thread Starter
  • #6
What you are planning seems reasonable. Looks like the previous owner was either a rubbish DIY'er or had dodgy tradesmen in. Lights over showers should always be IP rated and LV.
Cheers Mr Lives,

What about the fan? It's incredibly close to the shower, like literally just outside the cubicle. The ceiling's 9' high or so though. Should I change this for a 12v fan?

This it was tradesmen rather than DIY. Absolute cowboy job. Got a couple of pics of some of the connections but don't know how to add em. Will have to search how to when I get a chance.

Don

how are you planning to switch it on/off ,locally at the room ?
keeping it brief works sparks have short memory spans ......now where was i going?
Cable from FCU will be the circuit cable up to first junction box. From this first JB a switch cable will return to a location more or less right next to the FCU (which incidentally is in the utility room, just outside the shower room door).

From the JB the circuit cable will continue on to the utility room lighting JB. From each of these primary JB's a cable will run to a series of secondary JB's for each LV light fitting. Does that sound right? Also, from the primary JB in the shower room, a cable will feed the fan, which I will be changing for one with an overrun timer.

Thanks for the replies so far.

Cheers

Don
 
Last edited by a moderator:
W

wayne

  • Thread Starter Thread Starter
  • #7
you seem to have an idea of how it works.
for the fan position look up zoning in bathrooms
now for the legal bit ;can someone say whether this works will require "part p"notification ;off top of my head i think this will require a minor works cert
 
S

Shakey

  • Thread Starter Thread Starter
  • #8
this is notifiable and WILL require part p notification, even though you could get away with a minor works cert
 
D

DonaldJ

  • Thread Starter Thread Starter
  • #9
Cheers folks.

I figured it is notifiable because, even though it's sort of like for like replacement and there is nothing being changed or adapted, it is still work in a bathroom.

However, given that I am completely broke, so much so that I'm struggling to afford the lights, transformers, fan and switches etc, I am unable to afford the £180 or so notification fee that the LABC want. Therefore, I will not be notifying at the present time but if necessary (which I've no doubt it will be when I eventually sell the house), I will employ a qualified electrician to do it all again when I can afford it so it's all signed off properly. I am fully aware of the conseuquences of this but ultimately, what I am doing is, in any event, a hell of a lot safer than what is, or was, in place. Christ! You should see some of the cables. The connections are even worse. Some are so badly burnt that they literally crumble to dust when you touch them!

Re the fan, I've read about zoning in the past and what is allowed where etc but can't fully recall it all. I'll check it out again tomorrow - far too tired now to take anything in.

About those melted cables and connections. What's the most likely cause - any ideas? I was wondering if it's simply because the space above the ceiling is so tightly packed with insulation that any heat build up in the cables and connections is unable to escape. I know loose connections can also be a factor but I dont think overloading was a factor because when I removed the lights, transformer and cables etc it all seemed to be part of a B&Q kit and doesn't appear to have been doctored in any way.

Thanks again.

Don
 
W

wayne

  • Thread Starter Thread Starter
  • #10
how old is your cabling ?
you seem to have listed the main causes for burnt wiring ,i suggest its replaced before you have to buy a new house!
 
D

DonaldJ

  • Thread Starter Thread Starter
  • #11
The only cabling that's affected is the cabling n this circuit which is new blue and brown cable so not that old at all. The rest f the house wiring is fine, old colours but not reasonably modern and not that old fabric covered or rubber covered stuff.

The main parts burnt are the t&e at one side of a connection and the flex to the transformer on the other although there is a random bit of melting in the flex between the transfrmer and the light.

Is there any reason why I can't use 240v downlights? Got B&Q vouchers which I figure I can use for the replacement lights but their selction of 12v downlights is limited.

Also, for the shower light I thought that they HAD t be 12v for zone 1 but B&Q only sell one type and it's 240v suitable for zones 1 2 and 3.

Cheers

Don
 
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