converting commercial MH fixture into remote ballast assembly

In this thread I will show you how I convert a $30.00 commercial vertical one piece MH fixture into a remote ballasted system that can be used with either a horizontal hood assembly or the original vertical reflector.

The first picture, ballast socket assembly shows the commercial unit with the vertical reflector removed.

The next step is to remove the socket and U shaped bracket from the ballast assembly and cut the 2 socket wires leaving enough wire on each side of the cut to splice remote cord to. Then strip the end of the cord back far enough to install a ring connector to the green wire of the cord and reach to one of the mounting screws for a ground. Then splice the black wires together and the white wires together.

Then use a 4” round junction box cover with a knock out in the center, punch the knockout out and install the Romex type clamp/connector in the knockout hole and tighten the lock nut securely. Feed the cord through the clamp with the nut on the ballast side of the plate and install the extension cord socket on to the cord. (If you are using a full length extension cord, just cut it approximately 8” from the female end, feed it through the cover plate and fasten the cord to the ballast the same way I described above and it will save you from buying the ends for the cord.)

The the photo, detail of ballast cord, shows the cord installed through the cover plate/clamp assembly with the socket on the end. (At the extreme top you can barely see the stripped end of a cord for the next conversion with the ring connector installed and the black & white wires stripped for splicing) The photo, ballast with every thing installed, shows what it looks like after everything is screwed together.

I’ll post the portion for the socket end of the cord next.

In this section I’ll show how I finish the conversion from a single assembly ballast and socket fixture into a remote ballast system.

The first picture, socket with bracket, shows the socket and U shaped bracket as it was after removing it from the ballast in Part 1.

Now you need to take a 4” Octagon junction box with knockouts in the sides and the center of the bottom. Remove the knockout from the bottom of the box, center it on the wire hole in the bracket and drill 2 3/16’ holes that match the hole for the screws into the socket. Now is a good time to remove 1 of the side knock outs too. You will be assembling the socket to the U shaped bracket to the junction box using the original socket screws. You may have to modify the side of the U shaped bracket that goes towards the junction box to make sure that everything fits together snuggly. You could replace the original screws with longer ones instead of modifying the bracket, but you will have a gap between the bracket and the box. It only takes a little time with a grinder to make it flat.

The second picture, detail of socket, bracket, junction box without cord, shows how they go together using the screws to secure them together. The third picture, socket, bracket, junction box without cord, shows the lamp end reassembled before splicing the cord on.

Now install a clamp through the side knockout with the nut on the inside. Then splice a cord with a male end on it passing the cut end through the clamp first, then connecting the black to the black and the white to the white and install a ring connector to the green wire, place the ring connector under one of the 2 screws holding the socket-bracket-junction box assembly together to act as a ground.

The fourth picture, socket, bracket, junction box with cord installed, shows what the inside of the box looks like when the cord has been installed.

Now to finish it up you can use a blank 4” round cover plate for a reflector/hood assembly that is suspended by the hood or you can drill a hole through the cover plate and install an eyebolt if the reflector assembly will be suspended from the U shaped bracket/junction box, like I’m doing.

The fifth photo, side view of assembled vertical reflector assembly, shows what it looks like after you are finished.

The sixth photo, before and after, shows the way the ballast/reflector assembly started on the left and the way the finished conversion looks using one of my commercial vertical square reflectors instead of the round one that came with this particular assembly.

A few notes that may be needed for different commercial assemblies.

I used 4" octagon junction boxes and 4" round cover plates because the holes and slots in the cover plates exactly fit the existing holes in the bottom of the ballast and I had the 4"octagon boxes lying around. You will have to do some checking around a home improvement's electrical section for the boxes and covers that you can make work on your ballast assembly the easiest.

For one light assembly, I used as follows:

1 each 4" round cover plate
1 each 4" octagon junction box
2 each 3/8" x 1/2" Non-Metallic Connectors (Romex connectors)
2 each #10/3/16" ring connectors
4 each 16 gauge butt connectors
20' 14 gauge 3 wire cord
one set Harbor Freight 125 V 15 Amp cord plug/socket ends

If you don't already have a supply of cable lying around, then you could use a 20' to 30' 125 V 14 gauge 3 wire extension cord instead of the separate cord and ends. That is actually easier than the way I did it because all you have to do is to cut the female end off with an about 8" to 12" piece of cord left on the female end. Then splice the female end of the cord to the ballast and the long male end to the socket assembly. That way you don't have to install the female and male ends onto the cords.

The length of the cord can be as short as you need or up to at least 75' because 14 gauge wire is rated at 125 V for 15 amp up to 75' run, and a 1000 watt light will draw under 10 amp.

The rated voltage for approved cord is 600 volts, so you don't have to worry about exceeding the voltage either.

I hope this information and the information under the Splicing ballast to socket cable thread will help someone safely save some money.

This method will work for either MH or HPS systems. A remote ballast system helps keep a lot of the heat away from the plants and greatly reduces the weight you must support when you hang your lights and the weight you must fight while raising, lowering or moving your lights around in the grow area.

ONLY USE THIS INFORMATION IF YOU ARE COMFORTABLE WORKING WITH MEDIUM/HIGH VOLTAGE ELECTRICAL EQUIPMENT AND WIRING!

hi don where could I find these fixtures on the cheap? thanks in advance. orf

Look at surplus/used electrical shops. They should be listed near the elctrical parts/equipment wholesaler section in the yellow pages of the phone book. The shop I bought mine at is listed under "Electric Equip - Used" in the yellow pages of our Spokane phone book.

They are not the easiest thing to find, especially in HPS. Usually, you will find that a used seller will buy up a batch of them and sell them until they are gone and it may be quite a while before they get any more. Keep and eye on craigslist and maybe on ebay.

Make sure that the seller you deal with is honest and will either check the light for you or will let you exchange/return it if it doesn't work. Also, unless you feel comfortable in rewiring it to 120 volts, expect the seller to charge you to rewire it. If it is a multi-tap (multiple voltage), then all that is involved is opening the area where the input wires are, finding the current voltage wire cutting it and sealing with something to keep it from shorting and then connect the wire you just cut to the one marked 120v. Usually the light will have three wires with one going to ground - usually green, one going to the neutral leg --usually white and one going to the power leg -- usually black. Be absolutely sure that the light is labeled with 120 volts on the label and does NOT include a 240v rating because if it is wired for 240v, it is a 2 phase system and rewiring it can be a little more complicated.

If you find one and have questions about converting it to 120v, just ask or PM me and I'll try to help you or get you help from some of the electricians that follow the forums.

You might be interested in checking the DIY forum athttp://www.marijuanapassion.com/forum/showthread.php?t=29666

Which is Taters thread on build your own 6" cooled reflector/hood.

I think you will probably find that buy a new commercial light assembly and converting it will cost nearly as much as buy a new grow light already set up for growing use with a remote ballast.

Good smoking and good luck on finding the used commercial lights. Also remember that they may fail at anytime because they may have thousands, if not tens of thousands, of hours of use on them in less than ideal conditions.

If the running voltage is REALLY only 22V (I will have to get my DVM out and check mine) then your voltage/current calcs are WAY off.
1000W lamp at 22V: Almost 50 amps!!! Try to run 50A through 14AWG and it is going to vapourise. Something wrong in your measurement I suspect.
Is this a digital ballast you measured? You cannot measure the output using a meter. It consists of variable-width pulses. You would have to use an oscilloscope. I have a scope but I use inductive ballasts ...
However, good for you that you posted a thread complete with photos. I remoted mine a while back and find it much more convenient. I used the original reflectors: but I modified them by removing the bottom 4" and dimpling them with a ball-pein body hammer.

leafminer,

I would not be the least bit surprised if my voltage measurement is way off because I used an analog meter. I noticed in a ballast specification sheet that I was reading the other day both MH and HPS were listed as having output voltage in the neighborhood of 250 volts -- I don't remember the exact specs. My point was that it was well inside of the safe voltage for extension cords. Another thing to remember is normal extension cord material is NOT intended to have long term exposure to high temperatures. I would hesitate to use them where the max temp was much over 120F or if the sustained temp was much over 95F.

I like your idea of dimpling the original reflector. By a ball pein body hammer do you mean the one with the small almost pointed end on it or just a regular ball-pein hammer.?

I noticed the other day that my commercial reflectors with a vertical bulb and air flowing out of the top of the reflector around the bulb were much cooler to the touch and on the plants than my horizontal clone reflectors like Tater's DIY one. They also seemed to have a bigger footprint of light. Of course my horizontal hoods are NOT air cooled by fans and/or ducting.

I'm really considering building copies of my vertical commercial reflectors and maybe finding a way to air cool them, probably by enclosing them in some kind of a box like enclosure with a sealed lens on the bottom and running the ducted air flow through the box. I think I will also try to find some way to dimple the polished side of the reflectors in a controlled manner. If I could find one of the stippling tools that they use in gunsmithing, that would probably work, but I have seen excellent stippling done just with a hammer and a semi sharp center punch and lost of patience -- but I don't think I have the patience for that. Maybe using a needle gun from the backside my might work too.

Thanks for the idea and for correcting my voltage error.

Good smoking.

I think your measurement is not far off actually, but was that for a digital or inductive ballast?
I just took my DVM into the grow room and started the lamps with it connected to the HPS line. There was a starting peak of around 350V or more (it was fast so I could hardly catch the indication) then the voltage dropped practically to zero as the arc struck. It gradually climbed as the tube brightened, finally rising to 65V.

Now this is a 150HPS so at 150W, using the usual P=E*I, then 150 = 65.I and current must be 2.3 Amps. And I have this wired up with 12 AWG! (Ha ha) 16G would have been plenty.

Now 1000W tube - at the same arc voltage - would be 15.4A and need say, 12AWG I would think so as not to drop too many volts on the lamp side. However I do believe the arc voltage could be lower like your measurement suggests in which case I'd use something rather heavier such as 10 AWG at least.

Finally, you are dead right in the connection data - anyone following these instructions, guys, make sure you leave a decent sized tail of the original wire from the lamp socket, cut it closer to the ballast, because the mogul connector gets REALLY hot and needs high temp wire. Use wire nuts NOT tape!

I dimpled the reflector on a bean bag, the hammer was one of those types with a ball on one side and flat face on the other. Cut down and dimpled, these hoods work just fine and keep all the light in the growing area.

What amazes me most is pics I see here on MP of grows with CFLs and HPS just hanging in the air without reflectors! Most of the light being sent upwards, pretty useless.

I HAVE CONFIRMED THAT THIS TECHNIQUE WORKS FOR High Pressure Sodium AS WELL AS Metal Halide because I just got a HPS to convert and looked it over. I'm kind of in a hurry so I just converted it to 120v and hung it just like it was and am going to buy another one to make the remote conversion too.

I think it would probably work to convert Mercury Vapor lights to if anyone wanted to do it.

Good Smoking everyone!