Dimmer Switches

[The Medway Handyman]

Hi All

According to my leckie mate Alan (currently in Malta so I can't ask him) dimmer switches are the spawn of the Devil. Agin nature & no good will come of them. He reckons they are almost completely unreliable & nothing but trouble.

Anywho. Fitted one today for a customer. They had a energy saving bulb on the light somewhat like this

it up, nothing happened when it was first switched on. Turned it up & the bulb lit, then flickered & buzzed, then went out. Tried a normal bulb & the same happened. Both bulbs have a resistance so should be OK.

Only two terminals on the switch & two wires, one red & one black with red sleeve. Swapped them over & same thing happened.

Punter then told me the dimmer was a few years old & 'left over' from a hotel her son had helped to build. Hotels been there 15 years to my knowledge.

So, high chance the dimmer is U/S but I wondered - do dimmers work OK with these new fangled energy saving bulbs?

I'm sure I wired it right, but what would happen if I didn't? If its down to me not wiring it correctly I'll buy the punter a new one.

[Clive George]

If you click on one of the bulbs in the link you gave, you'll see the 'Features', one of which is "Not suitable for use with Dimmer Switch".

TBH I'm a bit surprised you didn't know this already - it gets mentioned here quite a lot.

cheers, clive

[Adrian]

The Medway Handyman ( [e-mail]) gurgled happily, sounding much like they were saying :

I fitted two dimmer switches (one a double) here a few years ago.

All died in fairly short order.

One - a single/clicky on-off/turny dim-bright - died in a "No Lights Working" kinda way in very short order. The other - a double/turny-off-dim-bright - has died in a turny-off-on kinda way, but took a bit longer about it. One half died a while before the other.

All were well within their rated power.

I think your mate has 'em summed up well.

Umm, no. No way. No how. Never. Thou Shalt Not Dim An Energy Saving Bulb.

(You can, I think, get dimming energy saving bulbs, but they're odd things that go in four steps rather than "dimming" like normal bulbs)

[Owain]

No.

Depends if you take the viewpoint you wired it up to the wrong sort of lamp, or the customer supplied the wrong sort of dimmer for you to install :-)

No point in buying new dimmer unless you also buy new lightbulb.

Owain

[Colin Wilson]

I think i've had to replace the same switch 3 times in 18 years - the first one lasted the longest at about 13 years, so while they're not "fit and forget" they're not a constant source of hassle.

Its fooked, replace the dimmer. Mine did the same about 3 weeks ago. You may find it also flickers when you start to dim it, without failing completely.

Not often, although someone posted a link to new fluorescent lamps being introduced that are dimmable.

[Guy King]

The message from "The Medway Handyman" contains these words:

Dimmers don't work with fluorescents.

[Andy Hall]

Your mate Alan has it the wrong way round. The dimmers are fine, it's the so called energy saving lamps that are the spawn of the devil.

[John Rumm]

Nope...

Chances are it is shagged if it did not work on an ordinary bulb (connecting to the compact fluro may have killed it!).

As to reliability, IME I have found them to be mostly reliable:

I have 8 dimmers here in total, 2 of which are touch dimmers (one needed its internal fuse replaced once in 13 years), 1 is a click turn type of dimmer - this failed once not long after fitting as was replaced with another which has gone for about 5 years. The rest are two way push on/off turn for brightness types. These have all worked fine since install (some 13 years, but most about six).

To put that into context, I have replaced at least two ordinary switches in the same time due to dirty/bouncing contacts.

[Guy King]

The message from John Rumm contains these words:

We had half a dozen - all but one have gone now, replace with ordinary switches so we can use LE bulbs. I spent a week or two looking at how we used them and decided that we so rarely dimmed them that we might as well just have a table-lamp or uplighter for the times the main lamp was too bright.

[John Rumm]

I found the arrival of children on the scene prompted a big expansion in dimmers - the ability to get up repeatedly in the night and be able to see without being dazeled suddenly became more necessary! ;-)

The remote control one is nice for home cinema applications - sit down comfortably, and then fade the lights down for the main presentation!

[David Hansen]

On Wed, 18 Oct 2006 22:13:01 +0100 someone who may be Guy King wrote this:-

Not with normal compact fluorescents.

Linear fluorescents can be dimmed, but it is a bit more complicated than with a filament bulb.

[meow2222]

Sounds about right. Theyre also prodigious wasters of energy, with bulb efficiency nosediving as theyre turned down. Far more sensible to use a separate lower power bulb if you want lower ligting levels.

Best > A demo I've done a few times is to

NT

[Dave Plowman (News)]

I've got 15 scattered around the house. All in grid switches so mainly made by Home Automation. Only one has failed, and that was the control pot which I managed to replace. The oldest ones are near 30 years old.

[meow2222]

Reliability seems to vary a lot according to make, with many makes being unreliable. I've seen some where the voltage put on the pot track is well in excess of what the pot could handle for any realistic length of time. Dimming seems to be a lose-lose operation.

NT

[Dave Plowman (News)]

Going to look brilliant that. Unless a twin filament type will look like one has blown.

Most don't fit dimmers to save energy. They're to give a 'mood' So the effect - and what it looks like - is the important consideration. If saving energy or the cost is important, but the 'look' not, you wouldn't start out with filament lamps anyway.

[Guy King]

The message from John Rumm contains these words:

That's the only one left - in the youngest's room. Even then I often just turn on her bedside reading lamp which is a 4W R50 LE bulb which starts very slowly.

[Guy King]

The message from David Hansen contains these words:

Indeed - I spent ages trying to work out the utterly counterintuitive switches that do just that in a nearby building.

[Staffbull]

Had dimmers in the lounge and bedrooms of the last house and this one, not one failure !! just dont try and dim "undimmable" luminaires :-)

[meow2222]

Everywhere I've lived I've had some lights on and some off much of the time. Has looked fine. I accept it might not if you design a lighting scheme that relies on symmetrical presentation, and switch the lamps asymmetrically.

Twin filaments are available in the US, maybe they'll catch on here some time. In the 30s 2 bulb fittings were more common, intended to run on this principle. Last one I used had a 40w and something bigger in it, giving 3 light levels from the twin wall switch. On original wiring IIRC. Leccy cost around 5p a unit then, very roughly comparable to =A35 a unit in todays money.

yes - but why fit a dimmer instead of fitting a 25w bulb? I've never found it hard to set up lighting that looks fine with some on some off. Which lights I have on determines the light level. Its much more comfortable that way, as well as lower energy use. What sort of lighting do you use that doesnt look good like this?

NT

[Andy Hall]

Because the light from a 25W bulb does not look aesthetically the same as that from a dimmed 50W one.