Saturday, June 8, 2013

LED Downlights - MR16 12V, GU10 240V or 12V MR16 Backwards Compatible Philips Master Bulbs

As anyone living in Queensland knows, we're about to be further screwed by our state government and power companies on power costs to the song of 21.4% with no reasonable explanation why.

I personally think the laws relating to what a state government is allowed to do urgently need a shake up but that's a topic for another day (although I will say this - primary services should NEVER be privatised. EVER.).

Anyway, now everyone needs to scramble and do whatever they can to minimise the impact of this dick move.

So job number one for a lot of people is going to be getting their lighting sorted.

For me, this is a priority as my house uses exclusively 12V MR16 50W halogen downlights throughout.

That equals one big-ass power bill.

For the uninitiated, there are two types of downlight voltage and socket formats (with the LED incarnation pictured below):

1: 12V LED Light (achieved using a transformer hidden in your ceiling - one per light) with MR16 pins.

2: 240V LED Light with GU10 socket.

I've got the first type (12V/MR16).
So off I went and whacked a 5W LED 12V MR16 globe in there and no dice.
The thing wouldn't even turn on.

As it turns out, 12V/MR16 LED lights are only designed to work with special LED transformers.
The two older types are electronic (what I've got - small and light plastic things) and iron core (big and heavy funnily enough).

Now apparently the Iron Core transformers will actually make your LED lights work however they will shorten the life span of the bulb.

Some good information on the topic is available here.

Anyway - I'm now faced with the situation of having to get this compatibility issue sorted.

The three options I've got are:

1) Replace all the electronic transformers with LED transformers and use 12V MR16 LED lights

2) Throw out all the old transformers and have a GU10 flexible cable wired straight onto the end of the 240V cable.

3) Replace 50W halogens with Philips Master MR16 12V Bulbs (with patented compatibility circuitry).

To explain the differences a little further, we need to get familiar with the anatomy of what's involved.

In either scenario, there is a transformer (also called a driver), a controller Integrated Circuit chip and the actually LED's themselves.

In the 12V/MR16 scenario, the transformer is separated out from the LED bulb which simply contains the IC chip and the LED emitters themselves.

In the 240V/GU10 scenario the transformer is integrated into the bulb (that long white bit at the top) as well as the IC chip and LEDs.

Now there's one other option to address this issue...
This involves using a specially designed 12V MR16 bulb made by Philips which contains patented circuitry  designed to work with old 12V electronic transformers (described on this page).

So I started reading up on each option and came up with a quick list of Pros and Cons for each:

MR16 12V
  • Separated transformer which allows bulb to run (almost) entirely cool giving best chance of long bulb life
  • If transformer blows bulb should survive (being that the bulb is the expensive part).
  • MR16 lights are generally a shorter profile so should fit better in convex gimbals (light fittings).
  • Higher deployment cost (new transformer for every light).
  • Sources suggest that use of any transformer (even LED specific) can potentially cause a fire.

GU10 240V
  • Cheaper to deploy as GU10 sockets much cheaper than LED transformers.
  • Bulbs cost the same as MR16 verisons.
  • Uses slightly less electricity as transformer integrated directly in bulb.
  • Integrated transformer generates some heat which may slightly shorten bulb life.
  • GU10 sockets require a ground cable to be wired in. This can be an issue if there's not a ground cable already running to the transformer.

MR16 12V Philips Master (Backwards Compatible)

  • Electrician not required
  • Immediately start enjoying power savings
  • Cheapest option overall
  • Still using a transformer so not perfect in terms of safety or efficiency.
  • 10W model has a fan which can become louder over time and seize due to dust or bugs (7W model has no fan).


I decided to give the Philips Master LED 7W a crack and they worked perfectly :)

I also gave the 10W version a try and can confirm that the fan sound is annoying and they aren't actually any brighter and they don't fit in standard halogen fittings properly (radius too large) whereas the 7W models are fine.

If you're interested there's a discussion concerning the Philips Master 7W going on over at Whirlpool that I'm participating in... (Not my thread).

I got a quote for re-wiring all my lights to GU10 sockets and when I did the math it worked out about $1300 cheaper overall to replace all lights in the house with Philips Master models as it did to re-wire and purchase decent (Philips Master quality or better) GU10 bulbs and new fittings.

Some personal feedback regarding the Philips Master bulbs is:

  • Generally speaking they are excellent
  • They are best suited to areas of a high concentration of LED bulbs (areas where my lights are spaced fair apart are a little bit darker than areas where they are close together).
  • The colour temperature is pleasant in the home.
  • The light output is solid. What I mean by this is that there is no motion strobe effect. I tried a Nichia 8W 60 Degree 3000K bulb and while it was compatible with my old transformers the light it produced it obviously wasn't cycling very fast. To clarify, when you look at the light it produces it appears solid and there is no flickering. When motion occurs within the light coverage area however the object creates a strobe effect (imagine a very old movie with a poor framerate where the motion is very jumpy).

The only area in my home where they don't quite cut it is the main dining area where the bulbs are unfortunately spaced very far apart.

I will probably have to bite the bullet for these four bulbs and get some LED transformers por a GU10 socket installed so I can increase my bulb options to get some super-bright Cree LEDs.

Hope this has helped and that your decision is easier than mine was!

By the way - all work involving 240V wire connectivity alterations must be carried out by a licensed electrician (duh).

Also (and this is a bit of a grey area) I would personally make sure that any bulbs you purchase meet Australian standards.

The only standard I could really find that they must comply with is C-Tick however according to what I read on the interwebs the manufacturer isn't required to put this on the packaging.

Chances are if they've paid for it they would though.


  1. Thanks, I am in the same boat but I'm going to go the GU10 option as my transformers are a complete mixed bag / old / broken.

    This is a great article on the subject and you spelt it all out nicely :)

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