I have a Castaldi Lighting D06K/MH150G-AL industrial lamp. It is fitted with an Osram Powerball HCI-T 150W bulb that has a flux of around 15,000 lumen. I find this to be too much and I would like to replace the bulb with something producing less intense light.

Doing a bit of research I have discovered that metal halide lamps are more complicated than the usual household lamps I am used to where a bulb replacement mostly involves figuring out the socket being used. Here is a photo of the label on the circuit inside the lamp:

Lamp circuit

Is it possible for me to replace the bulb with a similar bulb with a lower power rating (e.g. 70W or even 50W)?

As an alternative, is it possible for me to replace the bulb with a LED bulb? I have seen these being manufactured and sold in China. However, I have no idea what specs to look for to ensure that they will work with my lamp. If the LED bulb requires 230V AC I can bypass the circuit in the lamp. However, a casual search only seems to produce LED bulbs rated at around 1,000 lumen which may be too little.

  • A [metal-halide] tag might be useful. However, I do not have enough reputation to create this tag. – Martin Liversage Feb 5 '17 at 0:26
  • @Ecnerwal: I did read the help first but I wasn't sure if my question was off topic. However, I have found several questions about metal halide bulbs and tinkering with these seem to require knowledge of electrical engineering which I lack so I decided to post my question here. – Martin Liversage Feb 5 '17 at 1:11

You cannot just replace the lamp, you also had to replace the coil so it matches the power of the lamp. Sometimes you had to replace even the starter with a matching type.

LED lamps available in shops typically don't have more than a few thousand lumen but you could look for LED retrofit lamps for street lighting on the net. They are available for E27, E40 and other sockets, too. Of course you had to remove the coil and the starter from the lamp fixture then.


As a rule, lamp must match ballast. But in discharge lights, there are a few exceptions where a ballast can drive several sizes of lamp. I've seen them, but I'm not enough of a discharge-lamp wonk to remember the particular ones. A lamp expert or good shop would know (certainly not big-box retailers).

There's no problem getting an LED replacement intended to replace sodium, mercury vapor or metal halide lights, at any power level including OE. They are very, very bright. They are not sold at big-box. Nor are they cheaply made. You have to go to specialty shops such as 1000bulbs.com or your local lighting or electrical supply house. (Which is a place you should shop at anyway; have a conversation with them about price and selection vs. big-box.)

Keep in mind an LED lumen is worth at least two metal-halide lumens. Because a metal halide bulb is trying to light a sphere, and about 3/4 of its light falls on e reflector or the bottom of the socket. Reflectors aren't very efficient. Whereas an LED is trying to light a cone or wedge, which is actually what you want in nearly every case. If you wanted to spread or narrow light further, optics are very good at turning a cone into a different shaped cone with near 100% efficiency.

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