mr16 transformer sizing

[jimsjimsjims]

I am doing a ground up LED set up in my kitchen and have questions about sizing bulbs to transformers. I've used Phillips 120V Powercore strip lights in the past with great results (once I got an elv dimmer) but am running into some problems now that I am moving to 12 volts. I was pretty set on the Endura series bulbs but was told by the rep that any transformer would need to be sized to the wattage that a bulb would be replacing and not the wattage of the bulb itself. In the case of one of my runs (12 bulbs) that would mean a pretty gigantic transformer. I looked into the Sylvania dimmables and their transformer compatibility docs show them to work with much lower power transformers (in one case the have 6x6 watts running fine on a standard WAC 100 watt electronic). I was hoping for a pretty high lumens/bulb (Phillips) but might be able to work with the lower power (Sylvania) if I had to. It just seems silly to buy a 750 watt transformer to run 120 watts of bulb.

My questions:
1. Is Phillips just being extra careful or is their bulb set up solely as a drop in replacement?
2. Are there any mr16 gu5.3 bulbs that are made specifically for lower power electronic transformers?
3. Any time frame for XLamp MT-G LED products coming to market?

Thanks in advance :)

 

[BM_lol]

1. If Philips suggests to consider the nominal wattage instead of actual wattage for 12V lamps it's probably related to ensuring the long lifetime of your transformer (no point for the bulbs to run 20 yrs and your transformer to die in a few yrs right?).

The Endura bulbs are 35W replacements, and if you use 12 of them, according to Philips suggestion you should have at least 700W load on your transformer. As for the Sylvania bulbs, by the same suggestion, the transformer should have 120W load since each is 20W halogen replacements (6x6)

2. I'm not aware of any having this sort of claiming.

3. The Cree 12V lamp they mentioned is only a prototype, and no timeline has been announced publicly to mention when they are commercialized. What I dug up is a smaller brand called Ledzworld that uses the MT-G chip and claims relatively high performance that you could consider.
http://ledzworld.com/2011/02/24/ledzworld-launches-mr16-%E2%80%93-6-5w-cree-mt-g-with-450-lumen/

 

[jimsjimsjims]

I had not even considered that they might be worried about transformer life rather than bulb function. I'll definitely have to drop the bulb wattage down to the 6-8 range and bump up the transformer to at least get close to getting to their numbers. I'll probably order a mix of bulbs and do a bit of testing, but do you think that using an ELV dimmer and electronic transformer will drive them cleaner than a magnetic set up?

 

[BM_lol]

First, you should consider if you are using the MR16 for dimming as it does affect the type of transformer used. From what I have heard, there are more problems with ELV transformers than magnetic ones. Most major brands of MR16s with Energystar should have a dimmer and transformer list that shows the working combinations that you can use as a reference.

PS: Keep in mind your bulb could potentially run for 20 years, but does your transformer run for 20 years as well?

 

[kalekainxx]

There are dimmable MR16 bulbs that don't require an external dimmable transformer. Then can be installed with a standard transformer and dimmed with a standard incandescent dimmer.

 

[ferratilis]

As with anything that is ran on max capacity, a transformer that is ran on it's max output will run hot and will go out faster. Other factors beside lamp wattage, like transformer efficiency and wire length is something to keep in mind when choosing a transformer