18 LED bulbs in to 2-gang dimmer... help please

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WJS

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Hey there!

I have an open plan kitchen-dining room, each has a 3x3 grid of spot lights with LEDs. 9 LEDs per room, 18 in total, all going in to a 2-gang dimmer switch (so each knob controls 9 LEDs).

Now, when I first moved in a few years ago, I swapped all the halogens in the house (every room has spot lights) to LEDs. Some cheap-as-chip ones from eBay.

No other switches in the house are dimmers, just plain old on/off. They've been fine.

The kitchen-dining room though.... Bulbs have failed, and any dimming that's applied makes the fuse box sound like it's going to explode.

So, now I want to get around to solving the issue:
> buy proper dimmable LEDs
> buy a proper 2-gang switch

Sourcing the bulbs isn't a problem, however it's the dimmer switch that is a problem.

My understanding is that if each LED bulb (though 6W) is a "50W equivalent" then I have 18 x 50 = 900W, so I need a 2-gang dimmer switch rated for 900W, so each knob can control the (9 x 50W) 450W AOK without exploding the fuse box.

But my hunt for one so far has come up blank.

So .... do they exist? All I can find are 400W 2-gangs, which - as I understand it - won't help me.

Any help would be much appreciated. Puns about being dim and lightbulb moments also welcome.

Thanks! (y)
 
It's the visible light output that is the equivalent value. It has nothing to do with the wattage.

18 x 6 = 108W total. 54 on each switch. That's it.
 
How on earth can somebody have thought that it was a good idea to have used lights which are so bad at doing the job they are installed to do, i.e. to light up a room, that large numbers have to be put in in order to try and work round the problem that they are fundamentally the wrong sort of lights to use.
 
WJS,
FYI I have found that normal Dimmers have not been that good with LED bulbs, and would recommend you use a LED specific dimmer such as

Varilight V-Pro Led Compatible Dimmer that are LED bulb rated.

Not recommending TLC one way or the other (I bought my from a different stockist), but they seem to have a good range:
https://www.tlc-direct.co.uk/tcl/search?query=Varilight+V-Pro+Dimmer&Submit=Search
and I think this is what you are looking for at up to 250W of LED:
https://www.tlc-direct.co.uk/Products/VLJQP252W.html
sfk
 
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WJS,
"I don't need to get a switch above 400W" > correct, as ELI said you need a dimmer that matches the actual Wattage of your Bulbs - 18bulbs x 6W = 108W total.

And note that the dimmer I recommenced above is designed for LED so its up to 250W will work perfectly. (or rather I will say 'should' as LED always makes things a bit more complex)
SFK
 
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Hmmmm .... so the loud buzzing from the fuse box when I currently dim (plus the fact that the LEDs don't dim) is down to....
>under-loading?
>non-dimmable LEDs?
> some other mis-match between the lights and dimmer switch?

Thanks for any more pointers!

(y)
 
No idea why the buzzing, especially at the fuse box - but dimming non-dimmable LEDs with a normal Dimmer sounds a recipe for trouble at the bulbs and the dimmer.

Now I am going to ask troubling question - are the bulbs you are using 12Volt or 240Volt ???
I ask because if 12V then there will be 240V to 12V convertors before the bulbs. And your 240V to 12V convertors might not be dimmable!
Sfk
 
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Hmm, from a look back at the eBay items, they were listed as 220-240v.

It also lists them as non-dimmable (something I probably should have looked more in detail at the time).

So if the wattage on the dimmer needs to be 108W, is there a danger in getting one rated 200W or 400W, or can I buy without worry (obvs getting dimmable LEDs this time too).

Thanks!
 
WJS
Glad to hear that they are 240V as that makes it easier to replace non-dimmable with dimmable.

Those Varilight V-Pro Led Compatible Dimmers are rated "up to xxxW for LED" and so no issue on the dimmer being overrated against the bulbs - at least not that I have found.
I use the "Varilight JQP401W V-Pro LED Compatible Dimmer Switch 10 - 400W" with 3bulbs x 5W = 15W with no issues. However I do have issues when using standard dimmers. And note that the page you referenced also recommended Varilight dimmers.

Regarding your Fuse Box noise I found this regarding noise when using a standard dimmer:
"The dimming element is not a variable resistor, it is a semiconductor device (triac) that switches the load on at a certain point through each half cycle. You choose the point by adjusting the variable resistor. So instead of that lovely sinewave, the current waveform has horrible square edges. The filtering in the dimmer removes most of the higher-frequency components for EMC compliance, but the filter inductor can buzz if it's not a "potted" type. You will also be hearing the result of this distorted current waveform at the [fuse box in the] MCB, as they contain a solenoid element for rapid disconnection in the event of a short circuit. It will be causing the components to move, hence the noise." http://www.electriciansforums.co.uk/threads/dimmer-buzzing.26934/
sfk
 
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Crikey! Many thanks for finding that.

So it does just seem like it's an old dimmer switch with non-dimming LEDs.

Puzzle over, I will shop with peace of mind.

Thanks for all of your help!
 
WJS,
Just to add (and slightly correct) what I said above, I would recommend the following:
Varilight Trailing Edge Push Dimmer 2G 1/2W 2 x 250W
http://www.screwfix.com/p/varilight...va/98455#product_additional_details_container

Where when you look at the downloadable instructions it says:
DIMMABLE LEDs The minimum load per gang is 10W. Always choose LEDs that are “dimmable” and for the best performance choose dimmable LEDs from established brands. We cannot guarantee that all LEDs labelled as “dimmable” can actually be dimmed satisfactorily. The maximum load of dimmer should be de-rated for LEDs. See below or check www.varilight.co.uk/led for latest advice on loading. Maximum and minimum loads will vary according to make and type of LED. Refer to LED manufacturer for specific loading information. If in doubt, use 2 to 10 lamps per gang (or 100W, whichever is lower)

So it says "If in doubt, use 2 to 10 lamps per gang/switch (or 100W, whichever is lower)", and so you have 9bulbs x 6W = 54W (per gang/switch), which should all be perfect.

No idea if you are after GU10 bulbs, or if the correct colour for you, but you could also get 2 boxes (20bulbs) of these 240V GU10 LED bulbs and see if it all works:
http://www.screwfix.com/p/lap-gu10-led-reflector-lamp-345lm-900cd-5-2w-10-pack/9326p

SFK
 
WJS
Also.... these V-Pro switches are programmable and can be setup to do lots of different things to match different lights. BUT I never bothered changing the programming and simply used them as they were when the first came out of the box. :>
SFK
 
Hey Folks,

Many thanks for all your help on this. Turned out to be rather simple in the end. I opted for the "Varilight V-Pro White 2 Gang LED Trailing Edge Dimmer Switch 1 or 2 Way" from Amazon for £23, with 18 "5W LED GU10 Spotlight - Glass - 50W Replacement" - the dimmable and warm light option - from LED Hut (https://www.ledhut.co.uk/5w-led-gu10-spotlight-dimmable-option-glass.html)

I had always thought changing switches to be quite an involved task, hence having held this particular thing off for years, but all in all it was quite easy! Out with the old switch and bulbs, and in with the new.

Everything works perfectly, the dimming works, the colour of the bulbs is lovely, no more buzzing from the fuse box, and the dimmer switch does a very nice 'fade on' effect when you turn them on. Subtle, but noticeable and makes a nice difference.

Makes such a difference to the rooms, and it's not even night time yet.

So thanks for all the help, glad I asked this forum! (y)
 
WJS,
Thanks for update - always great to get closure. Glad all working.
Sfk
 
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