BATHROOM DOWNLIGHTS

[KEN RUCK]

I WANT TO FIT 6 DOWNLIGHTS IN MY BATHROOM, 3 TO EACH TRANSFORMER.
WHAT TYPE OF CABLE DO I USE TO WIRE THE DOWNLIGHTS TO THE
TRANSFORMER?
OBVIOUSLY THEY ARE LOW VOLTAGE DOWNLIGHTS.

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please see forum rule 6

 

[Job_n_knock]

I assume the lamps are either 35 or 50W. Make sure that the transformers are 150VA and no less. I use a cable that has good heat resistance properties. Its identical to normal flex but a little more robust. Normal flex has a number which is 3183Y, the cable I use is 3093Y. Get it from a wholesaler. The distance of the lamps from the transformer is important too as the longer the cable run, the higher the current therefore the larger the cable requirement, so keep the distance to a minimum. If you can ensure that its less than that then via a quick calculation of power divided by voltage gives the current...we get 50w/12v = 4.16A so 1.5mm will suffice. Always make sure theres plenty of room around the lamps, especially if you have lagging in the void around them or they will overheat. Strictly speaking you should use something called an intumescent seal which is basically a heat resistant bag that surrounds the fittings.
If you have longer cable runs you should consider using 2.5mm or even 4mm. Ive been known to have to use 6mm before now. It really is important that you get this right.
Useful sites to view: http://www.kevinboone.com/cableselection_web.html or http://www.diydata.com/electrics/bathroom_electrics/bathroom_electrics.htm

The manufacturers of these fitting also have in most cases a guide to installation...good luck

 

[Adam_151]

The distance of the lamps from the transformer is important too as the longer the cable run, the higher the current

 

[ban-all-sheds]

The distance of the lamps from the transformer is important too as the longer the cable run, the higher the current

Seconded!

Also, Ken -

ensure that the cables from transformers to lights are the same length, otherwise the lights will differ in brightness,

don't use one of those kits with 1 transformer to 3 lights, 1:1 is much better,

you only need firehoods if you need to restore the fire rating of the ceiling - their job is not to keep insulation away, and they do not prevent heat build-up,

and are you aware that this work is notifiable?

 

[KEN RUCK]

THANKS, VERY USEFUL INFORMATION

 

[securespark]

I assume the lamps are either 35 or 50W. Make sure that the transformers are 150VA and no less.

Job

This is lost on me - can you explain your reasoning?

 

[Job_n_knock]

I WANT TO FIT 6 DOWNLIGHTS IN MY BATHROOM, 3 TO EACH TRANSFORMER.
WHAT TYPE OF CABLE DO I USE TO WIRE THE DOWNLIGHTS TO THE
TRANSFORMER?
OBVIOUSLY THEY ARE LOW VOLTAGE DOWNLIGHTS.

If each trannie was only 100VA then......need I go on?

 

[Spark123]

The distance of the lamps from the transformer is important too as the longer the cable run, the higher the current

I think he means volt-drop...