loft light earthing question

Joined
8 Sep 2010
Messages
27
Reaction score
0
Location
Cheshire
Country
United Kingdom
Hi There,

I am intending to install a loft light at some point this week and was after a bit of clarification on the earthing.

Essentially I am going to follow this method which was on another post.

1) Check that your ceiling roses are wired with the 3-plate method - Have a look in them, you should see three sets of terminals (plus an earth terminal) - Each ceiling rose will have two or three cables going to it - if you only have one, this method will not work. The middle terminals should have red wires, the two outer ones (which feed the light itself) should have a black in each, one of which should have red sleeving on, (but this is often missing). These two outer terminals sets should also have the pendant connected to them.

2) Take a 1mm T+E cable from a ceiling rose to a switch box fixed to a joist in the loft. You will find that most or all of the roses will have three wires in, but the last light on the circuit should only have two - you will find it easier to wire it from this one if you can find it.

3) From this switch box, wire another 1mm T+E cable to the light fitting in the loft, and connect the light fitting to this.

4) In the switch box, connect the incoming and outgoing earths together to the earth terminal in the switch box, or if there is not one, into a 5 or 15A insulated connector block (don't forget to put green/yellow sleeving on the earth wires).

5) Connect both of the Neutrals together in the switch box into a 5A or 15A connector block.

6) Connect the incoming live (from cieling rose) to the 'C' connection on the switch.

7) Connect the outgoing live to the L1 connection on the switch (you may need to swaop this to the L2 if switch appears upside down when you have finished).


This all makes perfect sense, just a couple of queries :

- Rather than connecting the neutrals together in the switch box, would I be better off using a choc block ?
- The light is double insulated (no earth), so what should I do with the earth wire when I get to the light ? Just cut it back ?
- Am I OK to use a metal light switch/back box or should it be plastic ?

Thanks in advance
 
Sponsored Links
To connect the neutrals together use a connector block, aka choc block, but you'll need to have it tucked away somewhere safe where it can't be touched - inside the switch box is a good place.

Just because you've got a double insulated fitting, don't cut back the earth wire (cpc) in case it's wanted when the fitting is changed. Sleeve it and terminate in a connector block or the earth terminal in the switch box (if it has one).

Generally speaking you'll be better off with plastic if you're surface mounting. The metal back boxes are usually intended for being sunk into plaster. Plastic boxes are less unattractive, intended for surface mounting and naturally insulated, therefore safe. If you don't connect the earth and then use a metal box, you've installed an accident waiting to happen as you'll have unearthed metal.

PJ
 
Cool - makes sense on the neutrals.

In terms of the earth I was going to use one of these switches

http://www.astra247.com/1009/Electr.../Metal-Clad/?gclid=CIT7_O7o8bICFYTMtAodmSwAfg

So, Assuming I am taking an earth from the ceiling rose to the switch, I can then terminate it inside this switch. The bit I am unsure of is as I will then be going from this switch to the light how do I deal with the earth up to the light ?
 
I think what I am trying to say, is that I can wire an earth all the way up to the light fitting. Its just a case of what do I do with the hanging piece of earth ?
 
Sponsored Links
The earth cable (circuit protective conductor/CPC) that enters the light fitting should be sleeved green&yellow, then terminated in to a connection block and tucked away safely within the light fitting. Even though this light is double insulated, it could one day be removed and the CPC then required for the replacement fitting, also the CPC is important for the use in testing for continuity, polarity and Zs. So never snip or cut them off!
 
Make sure all the earths at the switch are connected, including the one to the light. Connect them to the earth terminals provided, ie on the switch faceplate and the switch back box. Make sure both earth terminals are 'linked', to ensure both the box and faceplate are earthed. A short piece of earth wire between the two terminals will be used.

You must use grommets or better still plastic cts glands where the cable enters the metal back box. This will prevent the sharp edges damaging the cable. Glands are best as they prevent foreign matter dropping inside. If you do only use the grommets, make the cable entry at the bottom so stuff can't drop into it so easily.

Send a picture of your work if possible, and we can see how you're doing.
 

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.


Are you a trade or supplier? You can create your listing free at DIYnot Local

 
Back
Top