Hi i just wired up some downlighters and think i have used the wron
cable what i have done is :
4 x gu10 mains voltage downlights got a 0.5m going from each downlight got 2 pairs going to a juction box then the 2 juction boxes going t another juction box where the 240 volt ring and switch arethe cable have used from the downlighters to the juction box is a 0.5mm 3 cor flex at 3 amps then i relised this could be wrong ( after i put all m floorboards back down ) I can use a 1mm 3 core 13 amps from the juction box to the main juctio box but would the 0.5 3amp be ok or do i need to rip it all back up an rewire using the 1mm?
The lights should be wired with T&E cable, not flex. 1sqmm might be OK but it's more usual to use 1.5sqmm, it's easier to use in general (less fragile) and gives you a bit more leeway as regards current carrying capacity.
The real worry though is where have you connected these lights to the existing wiring? They shouldn't be connected directly to a 'ring' if by that you mean a circuit supplying power to sockets. It's better if you can connect them to an existing lighting circuit (if it has the capacity) but if this isn't possible then connect them to the ring curcuit via an FCU (fused connection unit) with a suitably rated fuse.
I thought my reply was fairly explicit. No, it's not really safe, neither does it comply with the wiring regulations. The major risk is that there is no protection (in the sense of a fuse or MCB) for the fairly thin wire you've used to connect the lights.
If (as you appear to be saying) you have connected it into the ring circuit then the MCB protecting that will probably be a 32 amp one. A fault current considerably less than this could start a fire by overheating your added wiring but wouldn't trip the MCB.
If I understand you correctly, you have 4 lights in total. Two of them are connected to a junction box (Lets call this JB-1) The other two are connected to another junction box (JB-2)
Then these two junction boxes are connected to a third junction box (JB-3) where you lighting circuit supply is, and the cable from the switch is. The cable that connects JB-1 and JB-2 to JB-3 is 0.5mm flex. (stranded wire) The cable that connects the lights to JB-1 and JB-2 is the same. The only thing connected to JB-1 and JB-2 is the 4 new GU10 lamps. The only thing connects to JB-3 is JB-1, JB-2, the supply and the switch.
If this is the case, then it is not *currently* dangerous (but is against the regs) as all 4 lights combined are pulling a maximum of 200w or 0.87A
HOWEVER
Your lighting circuit will be fused or MCB'd at a rating usually higher than
3A, so the wiring should be rated higher than this (mainly because someone may uprate the lights in that room at some point in the future or connect something else to it)
The cable you have used is also the wrong type - It should be solid core Twin and Earth - 1mm is OK, but it is better to use 1.5mm - This should be used in all the connections, even to the lights.
You also mentioned before "where the 240 volt ring and switch are" Lighting circuits are not wired as a ring, so make sure you have connected these lights to the lighting circuit (rather then a ring main where your sockets are connected) - The easiest way to do this is to pull the lighting circuit(s) fuse(s) or trip the lighting MCB(s). I am assuming you have just replaced some lights rather than connecting a new set, so if you have connected the supply to the same place as where the old lights were, you should be OK, but it doesn't hurt to just check.
So, I recommend you take up the floorboards and do it properly, yes I know it is a pain in the arse to do, but you will then have the fuzzy feeling you know it has all been done properly, and any inspection of it in the future won't raise eyebrows to the tune of "Crikey, what cowboy wired this up for you!"
Next time, if you are not sure about something, ask BEFORE you start the job :-)
I wouldnt, but theyre better than the 240v ones. 12v halogens are more efficient, cheaper, more robust and longer lasting than 240v. But all these spotlight downlighters are very energy ineficient, and will add a surprising amount to your bills, and heat the place up in summer.
It will save you doing it in 6 months time when you realise that the cost and frequency of bulb replacement makes 6 quid a hit for LV ones seem really cheap.
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