Six Requirements for LED Hibays


Like other LED products is the LPW out of the product. There are several LED hibays with 100 LPW, and by the end of this year, it could 110 LPW. In the first half of 2014 it could be 120 LPW. Etc. Etc. Etc.
High performance fluorescent T8 lamps and ballasts can provide about 100 LPW, but if you put them in a hibay there are fixture efficiency and thermal losses, so there may only be about 80 – 90 LPW out of the fixture. Fluorescent is also a fairly mature technology, and very little effort is being made to improve it.

CMH lamps and electronic ballasts can provide 110 LPW, but inside a hibay, the LPW can range from 80 – 100. This technology is improving, so efficiency will increase. At least one manufacturer is working on the concept of lower wattage replacement lamps with the same lumens as existing ones, which can work on existing ballasts. For example, if you buy a 210W lamp and ballast now, when the lamp burns out it could be replaced with maybe 190W lamp. So wattage could be saved now and down the road.

For all technologies, it is not just LPW out of the fixture, but where those lumens are going. This can be called effective lumens. Since LED hibays can have very good optical control, they can often provide required light levels with significantly fewer lumens.

Lumen depreciation should also be discussed. High performance fluorescent T8 lamps usually only lose 8 – 10% of initial lumens over rated life. For CMH it can be about 20%. But LED may lose 30% at L70, which is end of rated life. So an LED system should be somewhat overlit initially or have some kind of constant lumen control system.


Many LED hibays only have about 70 CRI, because they use LEDs, which are used for exterior applications, and this is about the same CRI as quartz MH. But to compete with fluorescent and to be closer to CMH, at least 80 CRI is recommended in LED hibays. LED hibays with 90+ CRI could be developed.

High fluorescent lamps have 80 – 85 CRI.  Most CMH lamps have 90+ CRI, which can be a significant advantage in retail stores, convention centers, car dealerships, etc.


This is not that important in a conditioned space or one that does not very hot, but this can very important in many warehouses and industrial facilities. Often the temperature can be 20 – 40 degrees hotter at fixture height than close to the ground. So if it is 100F near ground, it may be 130F at fixture height. Some LED hibays are only rated for 120F or 125F, which is not good in hot applications. Even LED hibays rated for at least 140F, will provide less light at high temperatures, because LEDs get less efficient with heat.  Heat can also dramatically reduce light output of fluorescent lamps, but fixtures with better design and amalgam in the lamps can help. Heat can also significantly reduce electronic ballast life.

CMH and all HID lamps do not care about temperature, and provide about the same amount of light when very hot or very cold. But heat can significantly reduce electronic ballast life.  There are some applications, such as metal foundries, that are too hot for anything electronic. For these applications CMH or quartz pulse start MH with a magnetic ballast may be best.


For LED hibays, warranty is so much more important than rated life, because warranty is how long the manufacturer will stand behind its product.

Rated life is often consider L70, when the LEDs still maintain 70% of initial lumens. But various manufacturers use different ways for L70. Some manufacturers list a lower hour rating, based on not multiplying more than six times the tested hours of the LEDs, and others list a longer life, based on a calculated or projected approach.

What is very important is that L70 is only for the LEDs, which may last longer than the driver, electrical connections, exterior finish, etc.  So I do not care that much about rated life numbers, but want to know if the manufacturer will warranty the hibay, including LEDs and drivers, for ten years in most applications. Maybe for 24/7 and/or hostile enviroments, the warranty has to be less.

Some LED hibay manufacturers have a standard five year warranty, but will double it to ten years, if the customer pays an extra 5 – 10% initially.  A ten year warranty can really help customers to approve projects. Many end-users do want to approve a project if the payback length happens after the warranty expires. Since the payback can be over five years, the ten year warranty can really help.

Even if various warranties have the same length, please read them to see what they cover, because there can be significant differences. Often there is no labor credit.  For fluorescent and CMH, the warranty is usually 3 years parts only for lamps and 5 years parts and labor for electronic ballasts. Some of the extra, long life fluorescent lamps with up to a 67,000 hour rating, have up to a 5 year warranty.

For any lighting products, especially LED, what is the worth of the warranty? If the company has only been in business for one or two years, a ten year warranty may be worth the paper it is written on. With how LED technology is progressing, even some top name brand companies may not survive ten years. Often a third party insurance policy from a reputable insurance company is the best, because no matter what happens to the manufacturer, customers will still be able to get money to replace fixtures that failed during warranty period. Some LED product manufacturers have 3rd party insurance policies.


Most of the time it is good to get hibays that qualify for rebates. For LED hibays in most parts of North America, they need to be qualified by the DesignLights Consortium (DLC). But the DLC may have restrictions, which do not work out for specific applications.

Some rebate provides use the Lighting Design Lab (LDL) for approval of LED hibays. In certain ways the LDL can be better than DLC.

Many rebate providers require that fluorescent T8 lamps and electronic ballasts be approved by the Consortium of Energy Efficiency

There do not seem to be very restrictions with CMH lamps and electronic ballasts.


LED hibay pricing has been coming down, but it is still considerably more than other technologies. For a decent quantity, LED hibays, which can provide as much light as 400W HPS or probe start MH, may cost $450 – $650. There are some economy versions at a lower cost, and some of them may be a good value in some projects.

Good 6F32T8 hibays may cost about $150. There are some imported T5HO hibays for as low as $80, but again, sometimes you get what you pay for.

A CMH lamp and electronic ballast may cost about $150 and they can go into existing fixtures or in new fixtures at an additional cost. For any hibay, initial pricing is really a small portion of the life cycling, cost of ownership or long term benefits