junction boxes

[GregSmith]

I'm planning to replace a pendant with one or more mains voltage downlighters. Do I need 5 or 20 Amp junction boxes? Also, in their instructions, my lights say they mustn't be earthed. Is this right?

 

[alexnic]

5-amp.... you might be better running the cable from one light to the other etc. that way you will only have the one junction box.(where the mains cable comes into the existing ceiling rose)

Your lights will be 'double insulated' so there will be no parts on it that will inadvertintly become live, hence the reason for there being no earth requirement

 

[GregSmith]

thanks very much for such a quick response

 

[masona]

you might be better running the cable from one light to the other etc.

My downlighter connector terminal block was too fiddly and tight to put 2 wires into it. Oh why don't they make it slightly bigger !

 

[GregSmith]

yes i've noticed that. how did you connect them then

 

[masona]

Connected each lights to the junction box

 

[alexnic]

Good point ...

In that case you could use a single junction box and run each light to it and a 20A would probably be better , nothing to do with the rating it's just that there would be more room for the cables...

 

[masona]

That what I did and out of interest,I've seen people have 20+ downlighter how is it done,do they use more junction boxes or something like a bigger teminal junction box all in one ? or do they daisy chains them with difficulty!

 

[alexnic]

whatever is easiest ... sometimes it is better to use a central JB and run each light to it.

For 20 lights ... off the same 6A switch? quite a load unless they are low voltage

 

[GregSmith]

Is there a limit to the number of mains downlights I can put on one ring or from one switch? What's the limiting factor?

 

[breezer]

current is the limiting factor, most switches will only switch up to 6 amps

 

[spark]

It's not any harder to connect 20 lights than it is to connect 2 lights, just link from one to another. The only difference is that you need more links and JB's.

The limiting factors are the load already on the circuit, the size of protective device and the size of the cable. Switches are a factor, but 10A switches are easily available. 20 lights is well within the capability of most lighting circuits depending on the existing load.

The load will be the same whether they are mains voltage or low voltage. A 50W lamp is a 50W lamp regardless of whether it's 230/240v or 12v . The current drawn is inversely proportional to the supply voltage, meaning that if you increase the voltage, the current drawn will reduce. If the voltage is decreased the current drawn will increase. Switching 20 downlighters whether they are LV or mains will have the same load on the circuit and the switch. The switch operates the circuit on the primary side of the transformer on a circuit with LV (well technically they are ELV) downlighters, therefore the load switched will be the same. I'm only making this point to ensure you don't install LV downlighters thinking they are less of a load