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[gselectrical]

Afternoon. I have some low voltage down lights to install within a bathroom. Would it be ok to install 1 transformer (50-150W/VA) to supply 4 lights or is it best to have one (smaller) transformer for each light?

Cheers

 

[Brian 157]

What rating lamps are you using? If the tranny is rated higher than total lighting wattage you should be ok but I have had problems with unequal length feeds to low voltage downlighters from the same tranny, (keep all the 12v cables the same length) one tranny per light will avoid this problem (& leave illumination if a tranny fails) but it will of course cost more...

 

[gselectrical]

What rating lamps are you using? If the tranny is rated higher than total lighting wattage you should be ok but I have had problems with unequal length feeds to low voltage downlighters from the same tranny, (keep all the 12v cables the same length) one tranny per light will avoid this problem (& leave illumination if a tranny fails) but it will of course cost more...

35W, Tranny rated higher. Wasn't sure whether there was something in the regs about only supplying one piece of equipment or something. ?

Cheers

 

[ianmacd]

You shouldnt use a 50-150W tranny with a 35W load anyway as it will shorten its life (especially if the lamp blows). Some manufacurers (like snaplite) supply a tranny with their ELV fittings. If yiou are doing one tranny per light then look for trannys that start at 0w (0-70W for example).

 

[a1spark]

Trannys will also need to be accessible for maintenance either from above or through downlight hole.......if the latter, and its a suspended ceiling then its best to check they will fit through the hole before purchase...not all larger wattage sizes do especially if its a shallow void.

 

[gselectrical]

Trannys will also need to be accessible for maintenance either from above or through downlight hole.......if the latter, and its a suspended ceiling then its best to check they will fit through the hole before purchase...not all larger wattage sizes do especially if its a shallow void.

There's an attic. So access won't be an issue.

Cheers

 

[gselectrical]

You shouldnt use a 50-150W tranny with a 35W load anyway as it will shorten its life (especially if the lamp blows). Some manufacurers (like snaplite) supply a tranny with their ELV fittings. If yiou are doing one tranny per light then look for trannys that start at 0w (0-70W for example).

4 Downlights. 4 x 35w = 140w. Therefore load will actually be 140w.

Cheers.

 

[ianmacd]

4 Downlights. 4 x 35w = 140w. Therefore load will actually be 140w. Cheers.

I was referring to one per lamp.

 

[gselectrical]

I was referring to one per lamp.

Ok Ian.

So using 4 x 35W lamps with the 50-150w tranny should be ok? As in it wont affect the life of the tranny as is the case if only 1 was used.

Cheers.

 

[ianmacd]

No it should be fine. I have not seen any issues with differing cable lenghts on the ELV side as Brian suggests but that may be becasue they have been short lenghts (sub 3m) rather than largly different lengths so its something to keep in mind too.

 

[ianmacd]

If there is a loft above, make sure that the lights and tranny do not get covered in insulation and/or boards. If they are then you may need the plant pot type insulation standoff's.

 

[SPARKY TIM]

It could be a problem if the client replaces with 50 watt lamps at a later date.

 

[septiclecky]

35W, Tranny rated higher. Wasn't sure whether there was something in the regs about only supplying one piece of equipment or something. ?Cheers

35w x 4 =140w total with a 150w tranny what happens if the 35w are replaced with 50w as sparky tim says?

 

[gselectrical]

35w x 4 =140w total with a 150w tranny what happens if the 35w are replaced with 50w as sparky tim says?

Lamp holders clearly state "35W bulbs only" or something along those lines. So im hoping they can read.

Cheers

 

[septiclecky]

Lamp holders clearly state "35W bulbs only" or something along those lines. So im hoping they can read. Cheers

It has a RED man at a pelican crossing meaning dont cross but people do so don't rely on that

 

[SPARKY TIM]

Lamp holders clearly state "35W bulbs only" or something along those lines. So im hoping they can read. Cheers

Never underestimate the stupidity of customers

 

[ElectekAir]

Personally i would use individual transformers a little more expensive initially but if one fails only

 

[gselectrical]

It has a RED man at a pelican crossing meaning dont cross but people do so don't rely on that

Oh well.....they can give me a call when the tranny blows after replacing them for 50s!

Installing a trannie for each light now.

Cheers

 

[Evans Electric]

Lamp holders clearly state "35W bulbs only" or something along those lines. So im hoping they can read. Cheers

They can probably read but it wont stop them from putting 50w lamps in .

I did bathroom downlights once using a 400w toroidal tranny sitting the middle like great spider, trouble was the inrush surge kept tripping the breaker. Ended up fitting a type C .

I think its perhaps best to use individual soft start electronic trannys.