Just found this info.. anyone here ever try this?
Grazz
Converting an HPS Ballast into a Switchable MH/HPS Ballast
============================================
Please note - this can only be done with an HPS Ballast. If you are not comfortable with basic electrical work and concepts then I do not recommend you do this. Please take appropriate precautions when doing this type of work and when testing your results.
HPS and MH Lights both use the same Autotransformer Ballasts, the only difference between the two lights, is the addition of an "Igniter" module to the HPS, to actually start the HPS bulb. Because of this you can easily and safely convert your HPS light to a Switchable light.
This takes about 30 minutes to do. You will need the following:
1. Pair of Wire Clippers (may not be needed, depends on light manufacturer)
2. Wire Twist Nuts (2, maybe 4)
3. Dual Pole, Single Throw switch from Home Depot (optional)
4. Approx. 2 feet (depending on ballast design) of #12 copper wire
-----------------------------
Details:
In the above pictures, you will note that an HPS has 3 components, and an MH has 2. The Autotransforming Ballast and the CAP are common to both types of Light assembly. The third piece that is only present in the HPS assembly, is the Igniter module.
Coming out of the Igniter there should be 3 wires, labeled X1LAMP, X2COM and X3 or something similar. If these are not labeled as such or similar, STOP! Your light is non-standard and unless you are a certified Electrician, you should consult one before continuing.
If you trace the X1 and X2 wires back, you will see X1 goes to a 3-wire connection between the Transformer and the Light Socket, and the X2 leads to a 3-wire connection also going between the Transformer and the Light Socket. These are the two leads you want to disconnect.
There are two ways to do this:
1st way: you can make it a semi-permanent conversion from HPS to MH, if you want to switch back, you have to open up your ballast again and reconnect the X1 and X2 leads.
2nd way: install a dual pole/single throw switch in X1 and X2, and you now have an on demand, switchable ballast.
Option 1:
1.Unplug the light! I recommend it having been unplugged for several hours before working on it.
2.Disconnect the X1 and X2 wires from the 3-wire connection spots by untwisting the wire nuts.
3.Retwist the wires back together, and re-cap with the wire nut as you do this.
4.Place one (1) new wire nut on the X1 lead coming out of the igniter to cap it so it does not short. Do the same with the X2 lead coming out of the igniter.
You’re done - your ballast will now run a same wattage MH bulb. To change back, reconnect the X1 and X2 leads coming out of the igniter to the respective X1 and X2 leads you disconnected them from.
Option 2:
1. Unplug the light!
2. Find a place to mount your switch. I used a pair of tin snips to cut a small 1"x1/2" hole in mine since the metal was thin and the switch just pushed into it. I do not recommend letting the switch hang out a hole or something. This is high voltage and that is inviting disaster.
3. After you have your switch mounted, cut your spare wire into two leads long enough to run from the switch to where the 3-wire connections are. ** NOTE ** Your spare wire should be the same gauge (thickness) as the wire that is already being used in the lights wiring.
4. Strip your ends and connect one end of each wire to each side of the same pole on your dual pole switch.
5. Locate the X1 lead from the Igniter and trace it back to the 3-wire connection.
6. Remove the wire nut and untwist the X1 lead from the other 2 wires.
7. Connect the X1 Igniter lead to one of the two remaining connection points on your switch.
8. Take the wire you attached to the same side of the opposite pole on your switch, and connect the other end of it to where you just took the X1 Igniter lead from, twist all three wires together.
9. Twist the wire nut onto these 3 wires to remake the 3-wire connection.
10. Do the same process with the X2 Igniter lead.
You’re done - close everything back up and you now have switchable ballast.
Disclaimer: I found this information on the web, if you choose to modify your ballast do so at your own risk. The article also recommends testing the fixture in an outdoor location before use.
!!
