240v to 12v transformer lighting

[Steven123]

hi guys i am new to wiring downlights as i work with 240v.

but i am wiring downlights in my bedroom which require to be transformed down to 12v. there are 4 lights in total.

they are 20w bulbs., so i am told i eed a transformer for each light.

how would i go around wiring it, am i right in sayen i would

take a feed from supply and put it in to light swtich, and take 4 switch wires from the light swtich to each transformer, then link the transformer to the seperate downlighters?

any advice from would be appreciated guys.

 

[Steve]

Dont you already have a lightswitch? All the switch wiring should already be in place?

 

[Lectrician]

Just treat each light point as a 240v, and then stick a tranny before the downlight.....

 

[Steven123]

yes steve but i didnt know where to place them. so is this correct.

consumer unit - light swithch - tranny - downlight - tranny - downlight - tranny downlight - tranny - downlight

in series

 

[briwire]

You could get a 100VA transformer that would be big enough to deal with your 80w load. Just connect the live and neutral to the tranny input, then 4 seperate supplies to your lights from the tranny output.

 

[Steve]

yes steve but i didnt know where to place them. so is this correct.

consumer unit - light swithch - tranny - downlight - tranny - downlight - tranny downlight - tranny - downlight

in series

Do you know how light circuits work?

And no, not in series.

 

[followgers]

Do as Briwire suggested. Wire conventionaly, and put a seperate tranny before each fitting. You could have all feed outs coming from one easily accessable j.b, or run them as a simple mini-radial circuit like any conventional lighting system, with your switch cable coming off your first j.b.

 

[followgers]

Do as Briwire suggested

sorry, I meant do as lectrician suggests.

 

[Taylortwocities]

You could get a 100VA transformer that would be big enough to deal with your 80w load. Just connect the live and neutral to the tranny input, then 4 seperate supplies to your lights from the tranny output.

You could do this but you will need heavy guage wire from the tranny to the further lights. There will be more volt drop on the longer runs making those lights dimmer than the others.

 

[Steven123]

so you mean. have supply come from c.u into switch, then switch into tranny, and link all the tranny inputs together then take a switch wire from each tranny in the out put to the lights

 

[electronicsuk]

so you mean. have supply come from c.u into switch, then switch into tranny, and link all the tranny inputs together then take a switch wire from each tranny in the out put to the lights

What?!

Setup would be similar to the (presumably) existing ceiling rose arrangement. The ceiling rose would be replaced with a 4 terminal JB consisting of live loop in-out, switched live, neutral and earth. Primary side of 100VA transformer is fed between neutral and switched live in JB with an earth if necessary.

12v lights are fed from secondary side of transformer, either with one length of two core cable per downlight back to the transformer, or looping in-out of each light with heavy gauge two core cable.

Can't make it much simpler

If using one transformer per downlight, wiring is exactly the same as if the downlights were mains.

 

[qubit]

Hiya, electronicsuk what would you class as the heavy 2 gauge cable you mentioned? I assume you mean 2.5mm cable? Is 1mm cable okay for wiring between trannys and downlights (even if say I wired 3 or 4 in serial looped) and which cable thickness is used for wiring between ceiling rose and switch and tranny I hope 1mm is okay cus I have loads of it

 

[breezer]

View media item 2640 6

 

[mattylad]

Speaking as a DIYr....

When you bought the lights & transformer units, did the transformers not have the output wires on them already?

Its usually best to keep the distance between the transformer and the light as short as possible, lengthening it may cause problems, not only those of brightness. The longer the wire the greater the possibility of interference to other equipment (and before anyone says "tosh", yes this can happen).

Obviously it all depends upon the individual circumstances of where they are but you can daisy chain the feed to them or take individual feeds to the transformers back to a single junction box fed from the light switch.

Dont forget heat shields above the ceiling & removing the insulation from around them and the transformers if thats the loft.