There are a lot of similarities in the process of replacing a 400 watt metal halide light and a higher wattage 1,000 watt bulb, but a lot of differences that its worth discussing them here.
The most common questions we come across are:
“What number of LED watts will be required to adequately replace a 400-watt metal halide bulb?
“Every LED Company suggests different types of LED fixtures.
Can you tell us what 120 Watt LED fixture you would suggest to replace 400 Watts Metal Halide?”
The customers suffer at the hands of the misguided information. Those who are not aware of the LEDs may only think of picking a LED based on a perceived notion of an amount of wattage needed.
However, this is an inaccurate way to go about replacing metal halide or HPS fixtures. Picking LED based solely on power or watt is not a good approach.
We are going to share with you our hard-gained wisdom about LED lights that comes after years of experience along with some science approved advice for your facility on the best way to convert 400 watts Metal Halide to LED. So if you have a warehouse, parking lot, gym, manufacturing facility, shop or tennis court, we can show you how easy it is to convert from metal halide to LED.
If you need the easy way out, then just trust our LED lighting expertise and reach out to us. However, you can even try to do it yourself. Replacing metal halides with LED fixtures isn’t a complicated process at all and all you need is knowledge about the do’s and don’ts of it. Equally important is to go to the right place – we’re here to help. Contact Us!
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How many LED watts replaces 400 watts metal halide?
We think that it would be a waste of time to give you generic advice as you may ignore it. However, we think that you must know the primary thing that LEDs should never be purchased on basis of watts.
And buying 400 Watts LED to replace 400 Watts Metal Halide is complete overkill. And even buying an LED light based on the watts of another LED fixture is not advised. The reason is LEDs do not have all the same efficacies.
LED’s can produce the same amount of visible lumens consuming less watts than other traditional sources of light. We advise you focus on the lumens of the light you need. The more efficient LED lights will use less energy to produce these lumens.
What does lumen refer to?
You may not know about lumens at all if you have been using light sources like metal halides and HPS. This is because these traditional light sources don’t use these measurement metrics. The light strength of these traditional bulbs is measured on basis of wattage which is not the case with LEDs. LEDs use the Lumen metric.
A Lumen is the light measurement metric that denotes the amount of light generated by a light fixture or bulb. These light lumens are produced when the fixtures converts electricity to light. This may prompt you to relate wattages with lumens – but that’s not the right thing to do. LED lights do much better than the traditional light fixtures at producing light efficiently. This is why we told you to replace your metal halides with LEDs lumens and not watts.
A foot-candle refers to one lumen per square foot and measures light intensity. A lighting plan is done to generate data on the foot candles and quantity of light for any particular area by assessing the input values of light sources through advanced lighting software. Further, the software calculates the total amount of light at any given spot produced by all the lights that might affect that area.
The lighting plan makes planning a conversion to LED simple. It helps you in making calculated decisions according to the expected light results rather than making random guesses about the right wattage LEDs.
Finally, you will be thinking about the lumens needed to replace light fixtures and not watts consumed – which is the wrong measurement basis.
Quality of Light
We have talked in length about deciding the lumen output quantities of various light fixtures. Let us now come to discuss the quality of light. The scale used to measure the quality of lumens is called Color Rendering Index or CRI.
Usually, LEDs have higher lumen CRI ratings than the metal halide or other fixtures too. Thus, whenever you go for changing your metal halide light fixtures with LED lights, you will be selecting the LEDs with lesser lumens. It has been most noted that LEDs with lesser lumens, say 20,000, appear brighter than any metal halide lights producing 30,000+ lumens.
The CRI or Color Rendering Index measures the quality of the light emitted by any light source. You can know more about the relevance of CRI by reading here. The concept is quite complex to understand but to put it simply, it measures how close light quality can be to the ultimate light source, the sun.
Higher CRI means lesser lumens required.
400 Watt Metal Halide Initial Lumens and L70
As an example, lets use a Metal Halide that produces 30,000 lumens. This bulb, out of the box, produces high initial light output. But then their lumens start depreciating rapidly. They lose about 50% lumens at half-life and they last for about 15,000 hours. This means they lose nearly 15,000 lumens by the time they complete 7500 hours
Coming to L70, this term denotes the total hours any light fixture remains lit before its lumen output rate comes down to 70% of initial lumens. The L70 value of metal halides is 5000 hours. This also points out the fact that right after the metal halides are put into use, their light starts to lose quality and brightness very rapidly.
Reflection of light inside the fixture reduces lumen output
Out of the many factors that play a determining role in the setting of the right lumen amount for the replacement of any 400 watt metal halide, reflection is one. LED lights have directional lighting which directs their lumens to fall on a pre-set point. They don’t need any support like a reflector to deliver the rays at a fixed point.
The opposite is the case with traditional lights that have omnidirectional lighting and need reflectors to focus cast their light. However, in this process, loss of lumen happens with every reflected ray of light that bounces more than once off the reflector. Studies have shown that a lumen loss of about 30% can happen in such a reflective process.
For example, in a Metal halide fixture with 30000 initial lumens, a lumen loss due to reflection can cause the effective lumen output to drop to 21000 lumens.
Comparing photopic and scotopic lumens
Photopic and scotopic lumens are terms used for the different ways used by light meter and us respectively to observe any light. Photopic lumens are detected by devices like light meters or cameras while the Scotopic lumens are visible to the naked eyes as well.
Light rays like IR or UV emitted by light sources remain invisible to us. They are of no use for us but can be detected and read by light meters as output.
LED lights mark a contrast with most other light sources by producing light of the visible spectrum only. This means that LEDs will give a brighter light that is visible too despite having the same lumen value as any metal halide light fixture.
Converting from Metal Halide to LED Easily – Create a lighting plan.
LED Lighting Supply has been providing 1000’s of Free lighting plans for customers looking to convert from Metal Halide to LED.
Whether you need a free lighting plan or have questions about LEDs, our expert lighting team will help you make the right choice – whether that’s for a school gym or a 1,000,000 square foot facility.
Contact us for a free lighting plan or to discuss your LED lighting goals.
About the Author
Dwayne Kula is President of LED Lighting Supply. On any given day, Dwayne is writing content for the site and helps manage the marketing initiatives that are on-going. He has a Software Engineering degree and still dabbles in writing software for the company as needed. When not working, he enjoys spending time with his family, working out, playing the occasional game of golf and exploring New England.