Standard LED bulb in a HPS fixture?

[mark32]

So the guy that runs the receiving dept at work asked me to look at one of the (Loading) dock lights that wasn't working. I chuckled as I see that he has BR40 LED screwed into it. "That's the problem, you can only put a special bulb in here man" I informed him. He then told me that the other two fixtures have the same bulb and they work fine. Sure enough they both have the same LED bulb in them, huh. I then thought that the loading dock maintenance guy must have bypassed the ballast in order to use regular bulbs. I then noticed, on the initial fixture, the cord had been damaged and the grounded conductor was cut. After I made the repair I first put the LED in, it worked, then went in a 50 watt HPS bulb....and it worked! Can anyone make sense of this? Is anyone surprised by this?

 

[JFletcher]

wag, but the working fixture with the cut grounded conductor may have an improper bond between grounded and grounding, thus the EGC is serving as the neutral; did you check it for current? or was it only working after your repair?

If the LED is a direct replacement for a 50W HPS and the ballast is still wired up and operational, both bulbs will work interchangeably.

eta: just looked, BR40 is a floodlight made to run on 120V. It may be fine on ballast voltage, tho my second wag tells me it will have a very reduced lifespan over a proper LED HPS replacement for that ballast.

 

[480sparky]

Many of the newer LED lamps come with internal drivers that can run on a wide range of voltages. If the open-circuit voltage of the HID lamp is within the range of voltages the LED driver can operate at, then it will light just fine.

 

[mbrooke]

Not sure what the manufacturer says about it, but I'd disconnect the igniter.