Converting a standard HPS to a MH/HPS Switchable for less than $8.00

Ok if you are not comfortable working with electricity and do not know how to make safe High voltage connections,
DO NOT ATTEMPT

Now the discalimer is out of the way.
OK, you start with a standard HPS ballast and crack it open. Remember that most manufacturers will void the warranty if the ballasts seals are broken. With that said, lets begin the surgery. After the ballast is cracked open you need to locate the ignitor (generally next to the capacitor but smaller) and trace the wires coming out of the ignitor. Some are labeled X1 and X2 but we'll do this pretending that there are no marks on the wires. Two of the wires coming off of the ignitor will lead to a wire nut that holds three wires. Two of these wires comes directly from the remote light plug. I have labeled these X1 and X2. Seperate these sets of wires from the rest.

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Next you need to cut the wires X1 and X2 towards the middle of the wire in between the ignitor and the wire nut. You want these cuts to make two half length wires from one wire for X1 and again for X2. You want to strip 1/4" of the insulator off of each end of the 4 wires you have now. This is where you will attach the ring terminals in a step or two later.

This is the type of switch you'll want. It is a Double pole/Single Throw toggle switch rated for 15 amps. You can go higher than 15 amps, but do not want to go less than this. A 1000 watt bulb can pull up to 15 amps at startup. I picked this one up at Home Depot for $5.99. Try to make sure that the terminals are the screw in type. It makes it easier than having to solder your connections.

Next you want to crimp on the ring terminals to the 4 wires to the 4 wires you stripped in the last step. After those are crimped on (I triple crimp them for safety) you want to attach the wires to the switch. I start with the wires from the ignitor and attach them to either side of the two center terminals on the switch. Then you attach the other wires coming from the wire nuts to the other two terminal on the switch. Make sure to match up the colors of the wires to the corresponding terminals.

The next step is to drill a hole to hold the switch. Mine happens to be 1/2". The diameter of the hole should be a hair bigger than the threads on the switch so that the threaeds will fit through but small enough so that the little nut will hold it in. You also want to use some care here as to not puncture the ignitor or capacitor with your drill. I put my switch behind the handle so that in the future it is harder to accidentally hit the switch.

The next step is real easy. You just remove the supplied holder nut on the switch and put the switch through the hole you drilled and put the nut back on the switch securing it to the ballast housing. Reassemble the balast and you now have a switchable HPS/MH ballast. I usually test it to find out which side is the HPS and mark it with a sharpie. Test with the HPS bulb as it will not fire if the ignitor isn't in the circuit. Voila, you are done

Thats a great DIY post hall.

I'll add...anyone looking to upgrade, and have the flexibility of using one ballast for both MH and HPS...the electronic dual usuage ballasts are actually less than a comparitive magnetic drive switchable ballast.

But if you've already got one of those oven-like magnetic ballasts...hall's DIY is the way to go.

I like the digi's also. I have a surplus of these sunlight supply ballasts.

Awesome - I've been shopping around for this stuff and I'm a DIY'er. Nice to know I can tweak the ballast relatively easy. Thanks for the tutorial!:thumbsup:

Fade

my 150w HPS only has a ballast and a capacitor (may be due to low wattage), no ignitor, so does that mean it'll run MH without modification?

Does this mean that if you use a 400W MH ballast and add an ignitor (HQI style) it would fire a 400W HPS? I often have wondered about this...

4x5 Take pics of the setup. Maybe a part # and manufacturer of the capacitor would help. It might have an internal ignitor inside the capacitor. Which would be harder to convert. But could be done.

WillysWonder

Thats the theory. I will be attempting this for my 1000 watt Sunlight Supply Ballasts. Once I have succesfully done this, I will post pics. I do know that there is a difference between MH ballasts and HPS ballasts. I'll give it a shot and let you know how it goes, if the actual ballast coil can handle it then it should work. I know that MH has a higher startup voltage than HPS so it should be able to handle the load. A MH bulb has the ignitor in the bulb whereas the HPS doesn't. Cross yer fingers on this one. Once it is done I'll start a thread on convertin your MH ballast to a switchable.

cool. I will keep my eyes open for it...