Incandescent bulb in a 70 watt HPS fixture

[powerplay]

I have found two 70 watt HPS fixtures with 100 watt incandescent bulbs in them. I am uncertain if they ever worked, but the proper LU70 doesn't work in the one that had the regular bulb in it...did it damage the ballast/ignitor? Can someone tell me what happened..or would happen under these circumstances?Thanks in advance....

 

[Dennis Alwon]

Did you open it up and see if someone by passed the ballast and made it suitable for standard bulbs.

 

[dbuckley]

If tias a magnetic ballast, then the thing might work as is. The ballast is, after all, just an AC resistor to limit current. The lamp thus may be a bit dim, as the running voltage of a discharge lamp is less than 120V.

Note I'm not saying this is a good idea, far from it, but it might work well enough that the owner never complains.

E2A: I'm not sure an electronic ballast would be anything like as forgiving.

 

[hillbilly1]

It will work, but somewhat dim, I fixed one that the maintaince guy at a movie theater installed at a rear exit. Hey! the edison base bulb fit, why wouldn't it work:roll:

 

[broadgage]

Although fitting an incandescent lamp in an HID fixture is clearly wrong, I doubt that it broke the control gear.
I suspect that the control gear was already defective, and someone found out that it would work an incandescent lamp, but not the correct lamp.

If the ignitor had failed, then no high voltage pulse would be available to strike the lamp, but a filament lamp would light, though perhaps dimly due to the voltage drop in the ballast.

If the choke has gone short circuit, then that would instantly destroy the correct lamp, but light an incandescent just fine.

 

[Pierre C Belarge]

Did you open it up and see if someone by passed the ballast and made it suitable for standard bulbs.

The simplest answer, and the best answer...must be someone with a lot of experience...

 

[powerplay]

I did open it up and replace the ballast but never tried out the edison bulb to see what it would do. I had thought that since the HID ignitor was trying to strike a current across an connected tungsten filament it may have done some damage, as i believe the correct bulb has an opening filled with xenon gas/sodium mercury amalgam between two electrodes ...the light must have been defective in the first place, or perhaps burnt out prematurely from an edison bulb being used instead of the LU70? Thanks again.

 

[Electric-Light]

The fixture will provide enough open circuit voltage to sustain an arc, but not to start the lamp. The igniter doesn't deactivate the voltage across the socket.

I'm guessing the igniter died causing the lamp to not start, so they did a hack job using incandescent lamps that does not require a pulse to start.

 

[tom baker]

Using a incandescent lamp in an HID fixture is one accepted way to test the ballast. But the ignitor may of been damaged, I don't know for sure. A bad HID lamp will cause the ignitor to create the HV pulse to try and start the lamp, but with the wrong lamp? With a bad HID lamp the ignitor eventually fails

 

[puckman]

In hps fixtures you can use an incandescent bulb of the same wattage as the hps bulb to rule out a bad ballast. This I believe can be done with hps fixtures only. Other hid fixtures have differrent test methods.