What You Need to Know About LED MR16's

What You Need to Know About LED MR16's

BBBBUUUUUUUUUZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ, what in the world is that buzzing noise and why is it coming from my recessed lighting? This is probably the number one question we get at Energy Squad. Second on the list is why did my brand new LED MR16 that I just bought from 'insert big box hardware store name here' already burn out? "Aren't these things supposed to last like 100 years or something??"


Low Voltage LED MR16 GU5.3

High Voltage LED MR16 GU10

Lets start by making sure we all know the difference between the two most common MR16 bulbs. On the left is a 12V GU5.3 LED MR16 and on the right is a 120V GU10 LED MR16. The MR16 describes the bulb type, the face if you will. The 16 represents the width of the bulb in 1/8 inches. The GU5.3 and GU10 represents the base type. GU5.3 is always associated with a low voltage fixture and GU10 is associated with high voltage. The GU5.3 bulb has two prongs that are 5.3mm apart and the GU10 has two "stubs" that are 10mm apart.


Low Voltage Fixture Example

Connector Example for Low Volt MR16

For the purpose of this article we will focus on the Low Voltage MR16's. Just know that the MR16 GU10's are "standard" bulbs meaning they power directly off the 120V of power the typical home uses. These bulbs are generally found in track lighting and some appliances. Occasionally you will find them in 4" recessed cans. The way you will know is by simply twisting the bulb slightly (lefty lossey, righty tighty as my grandfather used to say) until they drop out of their sockets. Typically you will have less issues when using high voltage MR16's then you may have with a low voltage MR16.


What's that Buzzing?


Why won't this light dim lower?



I thought these LED's were supposed to last a long time?

So here are the three big questions/ complaints we get. Whats that buzzing? Why won't this LED dim lower? and Why did my new LED burn out in less than two months? 

Understanding the components involved with a Low Voltage Fixture will help you better diagnose and solve your problems. Question one and two tend to be resolved by reviewing the components and confirming everything is compatible. Question three is usually much easier to resolve so we will save that for last.

In a typical low voltage recessed lighting scenario, you will have a dimmer, a recessed fixture with a low voltage transformer, either magnetic or electronic and then last a LED bulb. Any one of these three components alone can be an issue so when you bundle all three together, you really are asking for trouble. If I had to put a percentage to which component the issues arise, 50% on the transformer, 20% on the dimmer and 30% on the LED bulb. Many of the existing low voltage fixtures that you will come across use very inexpensive transformers. This made sense considering you were only using a very simplistic halogen light bulb. Unfortunately the technology in these inexpensive transformers can play havoc on the technology in a LED bulb.

So step 1 would be determining the type of transformer you have. There are two types of transformers, magnetic and electronic. Magnetic are the more widely used but certainly you may come across an electronic transformer.

Step 2 would be checking to see if the dimmer you are using is compatible with that type of transformer. If the transformer is a magnetic transformer then you will need a forward phase dimmer. I always think of FM radio to remind me (Forward phase=Magnetic Transformer). If you have an Electronic Transformer than you will need a Reverse Phase dimmer or Adaptive Phase dimmer. I always think ER as a reminder (Electronic Transformer=Reverse Phase).  Making sure you are using the correct dimmer type with the correct transformer type can help eliminate many of these issues.

Step 3 is the LED itself. We have all heard the phrase 'you get what you pay for', well it definitely fits here. If you think of an LED as a small computer, which in some ways it is, then remember the less expensive LED's are not getting the best "processors". Since these aren't the best therefore the way they deal with the low voltage transformers can range all over the place. The higher quality products use better chip technology and therefore tend to handle the wide range of transformers being used. By no means is it a guarantee that the more expensive LED's will always work but more times than not, the better quality product will solve most issues. I would recommend having a few options on hand and when you run into one of these situations, swap out the lamp or lamps in question with one of the better quality products and see if your problems go away.

 The last question is usually answered by checking the packaging or manufactures spec sheet. If your LED is installed in an enclosed fixture or any fixture where air flow is minimal then you will need a LED that is rated for enclosed fixtures. Many manufactures keep their costs down by building LED's for open air installs. The technology involved in good thermal management is expensive and therefore the products that use this technology will cost more but if you have to replace your LED's every few months because you are not installing the correct product then it won't be long before that more expensive bulb looks pretty cheap. So step 1, understand the space you are working with. Is there ample amount of air flow? Do I need to consider an enclosed rated product? Does the orientation of how my LED is installed an issue and if so I better make sure I choose a higher quality product.


I know it seems like a lot of work just to replace an old halogen bulb and yes your are correct. Of all the replacement types, the low voltage MR16 is the most challenging. Hopefully understanding the components involved and doing just a little research will make these exchanges easier.

If you have a specific question concerning a lighting project you are working on, contact us for support.



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