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My old metal halide bulb finally died after 30 yrs use. Considering switch to LED corn bulb. However, the seller website states "Connects directly into E39 Mogul Bases. Just screw in. Please note that in some cases the ballast may have to be bypassed when changing to LEDs. Most are plug and play but please check. (LEDs uses a driver, not a ballast)". LED bulb seller's website

So my question is "How do I check?". Would like to go to LED for quicker starts, BUT... not if it means headaches with a ballast.

The original bulb is Philips PS Lifeguard H69KB-175 (as best I can tell... the writing is very faded after 30 yrs use.)

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You will need to bypass the ballast! Failing to do so will fry the LED.

Corncob LEDs are always a bad idea. They are inefficient. They intentionally defeat the best characteristic of LED -- that they make a wedge of light, which is what you really want.

Look around at lights. You have wallpack lights painting a super bright spot on the wall (useless), path lights lighting a huge circle not just the path ... and oh, the skyglow! Just here at this restaurant the car dealer's halide light is blasting in the window from across the highway. Meanwhile at the gas station, the canopy lights make the pump area glow pleasantly, but even the trees in front of the place are pitch black. Their lights are LED and are properly aimed. This saves them a fortune.

Cost savings is in aiming, not LED

Fact is, halide lights are about as efficient as LED. If you go with a corncob LED, you won't save any money unless the LED is less bright: this is a common con-job when selling LEDs. I saw one ad claiming their 45 watt, 3300 lumen LED is more efficient that the 175 watt metal halide . um... a 175W MH is 14,600 lumens. It would take 4 of those corncobs to make the same light, and it's actually less efficient.

Your linked one is 7000 lm, half the brightness of your MH.

On the other hand, if you aim the LED in exactly the wedge of light that you want, you're still no more lumen efficient, but you're only paying for the lumens that are actually on target. We once had seven 400W halide lights (3150W) lighting up a 400' right-of-way (and also, half the town). They were on city poles, so the location was not good. This was costing $1600/year. I specced a mere 250W of extremely well-aimed LED spots, $125/year.

Anyway, for former halide lights, I just mount an aimed fixture inside the old diffuser, aimed out the hole in the bottom. A tiny amount of splash light makes the diffuser glow, it looks nice.

  • My fixture is on my garage wall about 8ft higher than the garage doors. Ideally, the replacement bulb would shine a semi-circle and not illuminate the wall. I want it to cast light over the bulk of my driveway parking area (~40wide x40ft '). Light out the bottom is OK, but is not the bulk of where I need the light. If not corncob, what would you recommend. I want more light than the old 175w provided if possible. A quick turn on would be a big plus. – peinal Dec 27 '19 at 2:58
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The "PS" in your lamp part number means "Pulse Start", which is the way in which the Metal Halide bulb is initially excited to begin putting out light. That means it most certainly has a ballast in the fixture. So to use your LED replacement, someone will need to remove the ballast and run the wires directly to your mogul base socket (you can leave the old ballast in place if you want to, just wire around it). Before you do that however, you must ensure that the line voltage feeding your ballast is the same as what your LED driver needs; the spec sheet says 100 to 277V, so that would be appropriate for a "4 tap" ballast. If you have a "5 tap" ballast, the line voltage might be 480V and your LED would not work.

If you don't understand anything of what I just posted, you might want to hire a qualified electrician.

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Any halide I have seen had a ballast, larger than a fluorescent ballast. The simplest action is just buy a mogul socket instead of trying to figure out the wiring system of the halide . I wired up a 400 W from components and it has a large metal case , but I forgot what was in it but it was not just a couple wires.

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