Metal Halide to Induction Light Conversion




This instructable will show you how to convert a metal halide architectural light, commonly used to illuminate gymnasiums, outdoor stairwells and parking structures, over to a more energy efficient and longer lasting induction lighting setup.

While yours may differ, I am demonstrating on a RAB brand metal halide lamp, converting it over to Philips brand induction components.

I will also take a moment to mention that you will be working with electricity and this work should be only attempted by a trained professional. Always when working with electricity practice basic safety precautions and before you preform your work, make sure the power is switched off at the circuit breaker.

Step 1: Remove Outer Lens

Remove the four screws holding the outer lens.
Remove the outer lens.

Step 2: Remove Metal Halide Bulb

Simply unscrew the existing metal halide bulb. The bulb may be very hot! Please don't burn yourself.

Metal halide bulbs contain a high level of mercury, and they need to be disposed of accordingly.

Step 3: Remove Top Plate

Remove the four screws that hold the top plate. As you lift up the top plate, you will see three wires that connect to the underside of the top plate. Cut these wires and remove the top plate from the base housing.

Step 4: Remove Bulb Socket From Top Plate

We will be reusing the top plate, but the induction bulb uses a different socket so we can remove the metal halide bulb socket by depressing on the two spring clips.

Step 5: Remove Internal Components

We will not be re-using any of the internal components or wiring from the metal halide system so you can remove them now.

Should end up with a bare case that we can begin installing the induction components into.

Step 6: Prepare for Installation

The induction setup only has three parts, a generator (the rectangular box), the induction lamp and a glass induction lamp cover. We will mount the generator box in the base housing and the induction lamp will mount in the same location as the original halide bulb socket. Then when we are all done, the glass lamp cover just screws onto the induction lamp.

Step 7: Install Induction Lamp

This step will vary depending on which brand housing and induction lamp you are working with but it is now time to mount the induction lamp onto the top plate in the same location as the original halide bulb.

I made a paper template to ensure everything lined up properly.

First I had to trim a bit of the circumference from the original hole in the top plate (marked in red) to clear the mounting holes in the base of the induction lamp.

I also drilled a 3/8" hole in the top plate to allow the wires from the induction lamp to pass through.

Then I made a 2" mounting plate out of 1/4" steel and notched slots for the 4 mounting screws. This allows the original top plate to be "sandwiched" between the induction lamp and the mounting plate.

Once you are sure everything looks good and fits right, go ahead and remove the mounting plate and hit it with some white paint to make it pretty and keep if from rusting and reassemble.

When you are done, screw on the glass induction lamp cover onto the induction lamp.

Step 8: Install Generator

There were several existing threaded holes in the base housing for which to mount the generator.

I made a mounting bracket out of 3/4"x 1/4" steel stock and put a few bends on each side of the bracket to locate the generator in the center.

Once you drill your mounting holes and test fit the bracket, trim the excess off the ends of the bracket and give it a shot of paint.

Once the paint drys you can go ahead and mount up the generator to the base housing.

Step 9: Time to Wire It Up!

Now it is time to wire up the connections. This part is not as scary as it sounds. The generator even has a little wiring diagram on the label so just follow match yours to the diagram.

There are only two wires coming off the lamp that hook into the output of the generator. The black wire goes into the gray socket and the red wire goes into the orange colored socket.

On the input side, again just follow the diagram matching up the hot leg and neutral wires.

Then just add a grounding strap to the generator housing and you're done wiring!

Make sure to double check EVERYTHING before you turn the circuit breaker back on!

Step 10: Final Reassembly

We are all done!

Installation of the top plate and outer lens are the reverse of removal.
Just go ahead and reinstall the top plate onto the base housing with the four original screws and reinstall the outer lens with its four original screws.

There are many advantages to induction lighting verses metal halide. Most immediate is the energy efficiency of the induction system. There are studies that suggest that the light with a higher scotopic / photopic (S/P) ratios like that emitted from induction lamps is more conducive to effective nighttime vision. Basically the human eye can do more with less light so you can ultimately use much less watts of electricity to illuminate the same area. This can often yield energy savings upwards of 60% compared to a comparable metal halide system.

There are also energy savings when it comes being able to cycle the lights on and off to suit an application. When a halide bulb is on and at operating temperature, it can take up to 15 minutes to cool down after you turn it off before you can fire the light back up making it near impossible to implement these lights attached to any kind of motion detection system to save power. Induction lights are not similarly affected and you can turn them on and off at will.

A more long term benefit is the service life of the bulbs. Metal halide bulbs last approximately 10,000 hours where induction lamps last over 100,000 hours or just about 10 times the life of a halide bulb. When you are dealing with potentially hundreds of units illuminating a gymnasium or parking structure, the savings can really add up.

So now you can help the environment.... Just flip the light switch and be green!!



    • PCB Contest

      PCB Contest
    • Safe and Secure Challenge

      Safe and Secure Challenge
    • Warm and Fuzzy Contest

      Warm and Fuzzy Contest

    10 Discussions


    7 years ago on Introduction

    I like this instructable. Here in Des Moines, Iowa the local Northern Tool Supply remodeled their store. One of the improvements was the installation of the induction lamps. The store is definately brighter! I asked one of the employees what kind of lamps those were but he didn't know. It looks like a VERY large flourescent lamp. I have a work shop 30'x50' with 20' rafters, THIS is the light I am going to install and I also have a mercury lot lamp I am going to retrofit also.
    I did a search on YouTube and found a number of vids showing fixture modifications from MHD. This first vid shows the induction lamp like the one in this Instructable; the second vid answers alot of questions i.e.; how bright is it, how long will it last, how much less power does it use?

    I have attached a links for all to view. I hope this helps.


    9 years ago on Introduction

    Hey just for future use, the rectangular box is a ballast not a generator. Generators create electricity, ballasts transform it. Just thought I would let you know so people didn't become confused. Good job otherwise.

    2 replies

    Reply 9 years ago on Introduction

    Induction Lighting uses radio-waves to produce light, so, the box should be called a RF-generator.


    Reply 9 years ago on Introduction

    It is labeled by Philips as a "HF Generator" and is referred to in the installation instructions as a generator.

    The pole with the wire wrapped around it is the lamp and is what illuminates. The glass "bulb" is just a cover for the lamp.

    Really? How does it illuminate, I thought that pole with the wire emitted the high frequency which excites the gas in the glass bulb.

    The discharge vessel consists of a hollow soft glass bulb, containing a tubular re-entrant portion at the centre such that the antenna can be inserted into the lamp but is not in contact with the lamp's internal atmosphere. The re-entrant is coated with an electron emissive material, while the inside of the bulb is coated with a triphosphor fluorescent powder and anti-blackening agents. A thin electrically conductive coating on the outer surface serves as a shield to prevent radiation of HF signals outside the bulb. The internal atmosphere is a neon-argon mixture and because of the high operating temperature, special amalgams are necessary. One is attached to the re-entrant, while the other resides in one of the two exhaust tubes in the base.

    Read more here