Buzzing LED downlights

My house has many recessed halogen downlights which eat up a stupid amount of electricity, I want to replace them with LED ones, but my parents tried that a couple of years ago and couldn't stand the buzzing so switched back.

Has anyone successfully done this? The replacment bulbs aren't cheap (the amount I need will be over $500) and I don't have a dimmer switch to complicate matters. I've been told to replace the halogen regulator (?) with a 12 volt DC one for LEDs which will eliminate any buzzing, but that means absolutely nothing to me.

Downlights come in two types.

1) GU10 230V downlights - These bulbs/globes are connected directly to the mains power and operate at 230V.

2) MR16 12V Downlights - These have a transformer/regulator which changes the mains power into a low voltage (12V) and the bulb/globe is then powered by that lower voltage.

You can get LED blubs/globes for both types of downlight.

Buzzing normally only occurs when:

1) You try and dim a non-dimmable LED

2) You use an incompatible dimmer with an LED

3) You try and use a standard transformer on an LED

4) You use a poor quality LED which does not meet EMC requirements

5) Something else in the house (fridge, ceramic hob, hair driers, anythign with an electric motor in it) is emmitting EMC interference which is being picked up by the LED

I spent 7 years as technical manager for a UK company that designs and manufactures downlights. In that time I saw LED technology move on very quickly and the performance of the leading brands has increased dramatically. However there are a LOT of cheap, poor performing LEDs from Chinese factories which often lose 30% of their light in the first 6 months. Others are electrically unsafe whilst others will buzz like crazy.

If I were looking to buy some I would only consider those manufactured by GE, Osram or Philips.

The Philips LED technology is arguably the best available at the moment.

Brilliant info, thanks.

So how do I know whether I need the 230 or the 12V - I note they're different shapes, so is it a case of matching the shape and that should be right?

Cheers

Remove one of the bulbs/globes from your downlights.

On the top of the bulb you will see the electrical connections - It they're pointy pins (normally silver coloured), it's 12V. If they're T shaped (normally brass coloured) they're 230V.

There *may* be some printing on the back face of the glass too. Normally the manufacturer's name/logo and the voltage.

When looking at LEDs you need to consider:

1) Colour temperature - Are they called warm white or cool white? Some Cool White LEDs create a very cold, grey look in the room.

2) Lumen maintenence (How bright the bulb will be in a few months) - You need to look for something that shows it's lifetime with Lm70 or Lm80. This indicates the number of hours until the light drops to 70% or 80%. If the manufacturer cant tell you this, walk away.

3) Colour rendering - Does the lamp have a CRI number on the box? Some give the CRI on a scale of 0-1 whilst others give it on 0-100. This should be 0.8+ or 80+ depending on the scale used. Any less than this and colours will appear strange. You know how orange street lights make it difficult to tell what colour a car is? Thats because the CRI is very low.

4) Forget comparing the wattage when considering the light output. We all know a conventional 100W globe is brighter than a 60W, but some 4W LEDs are brighter than other 5W LEDs. Other 4W LEDs are dimmer than anoter 4W LED. Look for the Lumen value (sometimes stated as "lm") or the Candela value (cd). Beware that lm and cd are not interchangeable so make sure you compare like-for-like.

5) Beam angle - Its easy to make an LED with a narrow beam angle of 25 degrees or less. Making one with a 36 degree beam (like your existing lamps) is much more difficult. A narrow beam will create spots of light directly under the downlight and very little else. With all downlight types, a broad beam is generally better, for LED lamps it is very much a case of bigger is best.

Since being in Australia I've seen two stalls in shopping centers selling LED lamps. Neither of them have had any of this information.

The brands I mentioned above will have all this info and will proudly give it to you. Lesser manufacturers dont know the answers so they wont put anything on the box.

Very interesting thread. So after reading all that great info. I can just swap my 12v halogen globes for 12v LED's without having to do anything else??

Let me know if they last longer than the halogens.

Very interesting thread. So after reading all that great info. I can just swap my 12v halogen globes for 12v LED's without having to do anything else??

Sadly, its not quite that easy.

A 12V halogen will be operating on 12V~AC power. However, some LED bulbs need to operate on 12VDC. Also, some halogen downlights will be fitted with a transformer that will cut-out if under-loaded. This means that because the transformer is not being loaded with the 20W+ it expects, it will switch off.

Ironically, there is more chance of the LED working if the transformer you have already fitted is a cheap and cheerful one - The more expensive ones have the under-load cut-out.

It is often easier to replace both the transformer and globe for one GU10 230V globe. However you will need to get a GU10 lamp holder and connect the wires yourself to do the conversion - Or pay an electrician to do it for you.

LED technology is moving so fast that it is impossible to say what electronics (in the globe) will work with other electronics (in the transformer) - Therefore the easiest thing to do it remove the transformer.

If you're interested in trying LEDs I would suggest you buy just one to start with. You can then test if it works in your downlights and see if you like the light output. I suggest running the single LED for a few weeks before buying the rest of the set.

**STUPID QUESTION ALERT!**

Hi guys, I"m currently in the process of swapping out our halogen 12v down-lights for LED ones here in the UK. We're looking for a short term saving in running costs and then putting the original ones back in when we move and packing up the LEDs and taking them to Oz with us.

Shipping used lightbulbs might seem silly to some but we're talking about hundreds of pounds worth and if the stats are right, they'll still have plenty of life left in the them yet.

So, here's the question. Will the actually work in Oz? Presumably 12v is 12v wherever you are in the world so the MR16 type of bulb I'm talking about will be ok.

However, the other 240v types (E27 & B22), will they work? From reading this and other posts the standard domestic voltage is referred to as 230v. Does that mean this type is simply not compatible and there's no point in bring those?

Long time since the first question, but I took the plunge and replaced a couple of my downlights with LEDs, we have three switches controlling two lights each and replaced just two halogens with LEDs.

Absolutely fantastic, all we had to do was whip out the existing 12v transformer, the LEDs came with their own which we plugged into the wires directly, the holder fitted without needing modification, and the light output from these two LEDs is greater than all the halogens put together.

They weren't cheap; about $100 each but really cut down on the amount of lights we have on of an evening.

AND they don't buzz either.

Thanks Goochie. That's cleared few things up.