The Dangers Of Unprotected Metal Halides


I’ve seen a lot of crazy stuff in my 20 plus years in the lighting industry.

For those who are on the outside looking into this business we love, it might seem a bit crazy to associate “crazy” and “lighting industry.” Sort of like associating “comedian” and “CPA.”

But one thing that isn’t funny but is crazy is when lights start to explode.

This can happen, we’ve discovered, with metal halide lights.

First, let me make it clear – of all the lights in the HID (high intensity discharge) family, metal halides bring the greatest number of positive qualities to the table.

They’re more energy efficient than mercury vapor lamps and offer better light quality, and we sell a lot of them at Adventure Lighting, where our clients – and we – swear by them.

But they have their drawbacks.

Metal halides are notoriously slow to turn on. They also have color shifting issues more pronounced than other lamps and put out a lot of UV radiation.

And they can explode.

Not all the time or even most of the time or, to be honest, even some of the time – in fact we’ve only seen it a couple times with a few clients with the thousands of MH’s we’ve sold over the years.

But when anything blows up that isn’t supposed toand I can think of a long list of examples here – that makes people nervous, and rightfully so.

MH light manufacturers are working on this issue and have made great strides. Yet the best solution at this point is also the simplest – using a protected metal halide.

Unlike the unprotected version, the protected MH has a tubular piece of glass around the arctube that prevents glass breakage, should the bulb, on those rare occasions, explode – usually toward the end of the bulb’s life.

The protected metal halide can then be safely used in open fixtures and in areas where people and combustibles are present.

The protected MH costs a little more than its unprotected brother – but the peace of mind it brings seems totally worth it. Plus it also exposes more businesses to the wonderful qualities of the MH lamp.

And not using it, because of a little blow-up, is just crazy. 🙂



Jack Huff, along with his son Brian and wife Sue, owns and manages Adventure Lighting in Des Moines, Iowa. For more information, go to

6 responses to “The Dangers Of Unprotected Metal Halides”

  1. Ricky Cruz says:

    Can a protected M154/0 320W bulb be used in a M59 unit, or vice versa?
    I’d like to use protected bulbs in my standard fixtures
    Thanks – ricky

    • Good Question, and I’m glad you asked. You could be in for a problem here… The M154 and M59 are “ANSI Code Ballast Reference Numbers”. These numbers are meant to match up ballasts with their lamps. The M154 ANSI Code is for a 320W Pulse Start Ballast and Lamp. The M59 ANSI Code is for a 400w Probe Start Ballast and Lamp. These are NOT interchangeable, and doing so might cause the lamp to explode while you’re putting it in the socket. (if the power was on, which I also wouldn’t recommend.)

      Besides that, the question I think you’re trying to ask is, “Can I use a Protected 400w Metal Halide in a non-protected socket?” and the answer is yes. You cannot use unprotected lamps in protected sockets.

      We see customers and contractors alike try to save energy by lowering the wattage of the lamp in a metal halide or high pressure sodium fixture quite often. This is NOT possible. The lamps will probably fire up, but will explode and/or die pre-maturely. One cannot just use a lower lamp wattage to save energy with regards to HID lamps.

      There is an “Econo-Watt” version of the 400w M59 lamp. It is a 360w version that instantly saves 40 watts of energy. That is a good idea. Thanks for the question! I hope I didn’t ramble on too much!

  2. F Henrie says:

    Do metal halide lights brighten more after two or three hours?

    • They don’t. It usually takes about 20 minutes for a Metal Halide to reach its full light output. After that, it’s pretty consistent. With that being said, over the life of the lamp you will lose approximately 40%-50% of the light output of the lamp. So from the moment you plug it in, you’ll be slowly losing light output.

  3. neil says:


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