Pros & Cons - Mains vs Low Voltage Halogens ?

Aug 30, 2007 21 Replies

Hi



We're having our bathroom refitted and I've decided to replace the single 100watt light with 4 x halogen downlighters. The bathroom is



3metres square. What I'd appreciate advice on are the following:


  1. What's the best choice, low voltage or mains, and why?

  2. What sort of total wattage will I need to achieve a similar level of brightness to the single, centrally mounted 100W bulb?


  1. Are there any special considerations when installing halogens in a potentially steamy environment?



Thanks


You can use either. LV ones seem to have a longer lifetime.

Rather than using 4 x e.g. 35-50W fittings, using a larger number of

20W fittings near the walls works well. For example, 3 fittings on each of 3 walls, but it does depend on the layout. it's good to choose types that are adjustable and to use relatively wide angle bulbs. This way you will get a cone of light which will intersect with the wall producing a parabola of light.

Don't forget that the choice of tiles or wall finish in the upper part of the room will make a difference to the appearance of this. Natural stone tiles with texture are especially effective.

This is a great opportunity to make some mood lighting. You could look at grouping the lights and arranging dimming facilities with suitably IP rated dimmers such as touch plate types.

Not particularly, especially if you use LV fittings.

Thanks for the input Andy, dimmable lights would be a great idea, I hadn't considered it because I'd just assumed that regulations required a pull switch in bathrooms. Any idea where I'd find IP rated dimmers? Doesn't sound like something the sheds would stock.

>

you can get a pull cord dimmer - TLC stock it, search for dimpull

Owain

formatting link
are a couple of other releveant articles in the lighting category there too

LV dimmers with fixed dimming level can be made with a switch, 2 diodes and a heatsink.

NT

LV. It's brighter, the bulbs are cheaper and last longer, and its a tad safer in a bathroom.

about 3x50W

Not really. you can get showerproof fittings if direct splashes are a possibility.

I went for tiltable eyeball ones in the bathroom here..so I could focus on the bath and bog for readng, and the basin for washing and shaving.

Not a very bright idea. Running unidirectioal current through a transformer. Makes me rather too hot. won;t work with switched mode either.

LV wins every argument really apart from a slight increase in complexity when retrofitting it... see the wiki article for details.

Similar, or perhaps a bit more 120W - 200W should work ok in a room of that size. Many lower powered lights works better than a few big ones. As does use of wide beam lamps. Use of wall washer type fittings can make an attractive lighting display especially in fully tiled rooms. Having some control over brightness is handy so you can do the relaxing soak in the bath bit and still have the lighting required for close work in a mirror etc.

Yes, use at least IP45 fittings, or IP65 fittings if you want a light directly over a shower for example.

formatting link

Either you misread or your brain isnt working today. 2 diodes back to back does not make for unidirectional current flow.

NT Comprehension before criticism

Two diodes back to back do not allow any current flow. Perhaps you meant in inverse parallel, or side-by-side.

Steve

wher ws back to bak mentioned/.

Running two dides does bugger all on the HV side, and its a monstrous waste of power on the LV side. Might as well use a resistor.

which is still a crappy idea.

No mention was made of how they were to be connected. Anyone with any understanding of the subject can work that out.

Dimming is always a monstrous waste of power. Dimming on the lv side wastes about 10%, but more importantly its an easy way to get dimming for use in wet environment.

formatting link
dont recommend dimmers at all, but it does what the op wanted. Hopefully OP may decide to want something better, ie a switchbank.

NT

bollocks. A triac dimmer on the mains side itself waste very little power.

Dimming on the lv side

At the least. Maybe more.

I use mains side dimmers with electronic 'transformers' that understand dimmers. Works fine. Not a lot of heat..the switch plate gets a 'couple of watts' warm which is far less than is lost in the actual 'transformers'

are you not familiar with the nose dive in energy efficiency that dimming produces in filament bulbs? Figures are all on the wiki.

Which suitably IP rated dimmers do you rcommend for bathroom use?

NT

Sure, but why also throw away even MORE with a stupid way to dim it.

A bulb operating at reduced power is all infra ed and converts very little of its power to light no matter how you achieve it. That can;t be gotten away from. But using what amounts to a ballast in series with it

- and a resistive one at that if somewhat non linear - , merely makes matters WORSE.

If you want a zero loss dimmer, use a switched capacitor.

An=y that are fitted outside the door ;-)

Or work from a remote.

Rather extreme figures involving 500W halogen monsters dimmed to simulate 60 bulbs are on the wiki, not always a realistic example.

More to the point, dimming when used is about achieving a lower lighting level not reducing power consumption; the fact the power consumption is also reduced is a bonus. Having decided to install and use a filament lamp one has already accepted the associated full brightness running costs - so why would you be bothered when these are reduced a little?

formatting link

ok, I had to have a hack at it! See if it is any less rabid:

formatting link

Thanks for everyone's input on this, much appreciated...

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required