Downlighters for bookcases

[helpmeimdrowning]

Hi all,

I want to add clip on lv halogen downlighters to the top of some bookcases in the living room. Due to the layout of the room, I need to use three lv transformers to connect the various lights.

I have a free mains socket and rather than fit a spur to it I'd like to just plug the transformers in to the mains and also wire in a dimmer switch, so I can dim all the lights at once.

I've made the following wiring diagram, can anyone confirm it is correct?

Thanks in advance!

 

[ericmark]

A number of things don't seem to add up.
1) Halogen lights tend to get very hot. No correct that have to get very hot to work. Books and very hot don't mix.
2) To try and dim a halogen lamp is going to defeat the whole reason for using quartz halogen. The idea is the quartz envelope is so hot the tungsten will not deposit itself on the quartz. To use a dimmer would seriously reduce lamp life.
3) Low voltage lamps do not need transformers only extra low voltage need transformers and to work a dimmer with a transformer defeats the whole idea of using a transformer. They are not really transformers they are switch mode power supplies. They are specially designed to maintain exactly 12v at the lamps to increase lamp life.

Lamps like these are cool so will not damage books and clip on but can't be dimmed. There are many more options like this and another all clamp on and all are cool so will not affect books. If you really want to dim lamps then likely they will be fixed as that way you can ensure they will not be too close to books something like this uses non quartz bulbs and therefore can be dimmed without a problem. [/url]

 

[helpmeimdrowning]

Thanks for your reply!

I'll definitely follow your advice about using fixed lights, it's very wise.

My question is:

In our kitchen, we have 10 12v cabinet downlighters, installed by the sparks when we were getting our kitchen fitted. He took a spur off one of the mains sockets and installed a dimmer switch which controls all of the lights at once.

This is the effect I want for the bookcase lights. I know you can get dimmable 12v transformers and dimmer switches suitable for low voltage lights, and I wanted to see if I had the wiring correct for using these.

Thanks again,

Alan

 

[ColJack]

on the assumption that your dimmer switch is correctly rated for the load and spec'd for the transformers etc, and that it does not require a neutral, then yes your wiring looks correct for the circuit..

 

[Steve]

Why do you need to dim task lighting in a kitchen? If the lighting was appropriately designed, you wouldnt need to!

Task lighting should be T5 or T4 fluorescent strips. These give a much more even and cool light than ghastly halogen lights, and are about 5 times more efficient. You might only need, say 50 watts of fluorescent, compared to your 200? watts of halogen spot-heaters.

Dimming an incandescent lamp by 50% only achieves about a 30% energy saving.

Halogen spot lamps are about the least efficient form of lighting. Ever.

 

[ericmark]

I would agree. The main problem in most kitchens is they get too hot. Anything which can be done to reduce the heat must be a plus. Using discharge lighting will be the first step to a better working environment. Using an induction hob which puts heat into food rather than kitchen would be another. But the induction hob is expensive so best to start with cheap options first and resign to bin all tungsten lighting in kitchens.

As one moves away from kitchen the outlook changes where lights are only used when it's cold anyway so tungsten lighting is not so bad when one realises that the radiant heat will allow one to reduce to air temperature by 2 degrees yet maintain the comfort zone.

However one should not design an area using quartz lamps and dimmers. If dimmers are wanted then don't use quartz lamps. Other than the quartz lamps most lighting is low voltage. The extra low voltage lighting is in the main restricted to the quartz type lamps. With low voltage lighting there is no problem in getting transformers to work with dimmers as there are no transformers.

Although LED and Discharge lighting can be dimmed it is not easy. So using lamps with SES bases is likely the best option allowing small lamps without the problems associated with the quartz types.

Please note:- Low voltage is 230v the 12v lamps are called Extra Low Voltage.