CONVERTING AN HPS GROWLIGHT INTO A SWITCHABLE HPS/MH GROWLIGHT

I want to take a simple HPS growlight and add an MH ballast and a couple of dpdt switches. One switch for the power; the other one for the lamps (which will be changed). I'm not worried about the power switch; but the ballast puts out a "Starting Pulse" of like 4 or 5 thousand volts.

I'm no "Sparky" - so I just want to know if I will need some kind special "Pulse Rated" switch, or "High Capacity" switch for the lamps?

T.H.Cammo said:

I want to take a simple HPS growlight and add an MH ballast and a couple of dpdt switches. One switch for the power; the other one for the lamps (which will be changed). I'm not worried about the power switch; but the ballast puts out a "Starting Pulse" of like 4 or 5 thousand volts.

I'm no "Sparky" - so I just want to know if I will need some kind special "Pulse Rated" switch, or "High Capacity" switch for the lamps?

Click to expand...

Why? There are mh bulbs that fit hps fittings!

All you need is a switch to cut out the ignitor in the HPS wiring to run an MH bulb of the same power rating. They both use the same coil and capacitor. If your HPS ballast won't fire an HPS bulb but will run an MH bulb then the ignitor is shot. If neither bulb will run then it's most likely the capacitor. The caps should be checked to make sure they are still within their rated range as they will still work even if at only half but the light spectrum will be way off and the coil can overheat. I bought a $35 multimeter from Amazon that can test those caps and even tiny ones for electronics. Temp probe good to 1000F that's great for monitoring the temp when I decarb etc. Track the house wiring in the walls and all sorts of other good stuff.

I have a 1000w MH ballast that I figured the cap was shot in so got a new one and still no joy so looked it up online for the testing procedures to check the coil and it looks like the primary coil is shot. So probably was the bad cap and I fried it the last time I used it. At the time I thought it was the bulb so a good 1000w SunMaster Warm Deluxe was sitting on the shelf for 12 years after only one flowering run. Works fine in my newer ballast that does both and had it apart to replace it's cap and the wiring is just an on/off switch in the line that feeds the ignitor so dead simple. Easy to find tutorials on many sites or UTube.

No special switch needed as the switch is on the low voltage side of the transformer and just has to be rated higher than your line voltage and normal amperage. I'm no Sparky either but this is easy enough as long as you can follow simple instructions or diagrams. The hardest part for me was figuring out which holes to plug the cords in the multimeter to test the high voltages from the transformer. Those Chinese manuals translated into what is supposed to pass as English leave a lot to be desired sometimes.

The switch goes where it says Blue X3 wire on the diagram.

oill said:

Why? There are mh bulbs that fit hps fittings!

Click to expand...

I have conversion bulbs for both ways but they are a lot more expensive than the bulb to match the output. I have a 940w Hortilux HPS I got when I only had the 1000w MH ballast and it cost me $170 5 or 6 years ago and retails now in Canada for $300. Big as a football and barely fit in my reflector but my light meter pegs it way higher than any other 1000w bulb i have.

Standard bulb next to it. That's an 18" ruler too. The one on the left gives MH light from an HPS ballast. The big one does the reverse and has the ignitor built into the bulb so it can run off the MH ballast which doesn't have the needed ignitor..

OldMedUser said:

I have conversion bulbs for both ways but they are a lot more expensive than the bulb to match the output. I have a 940w Hortilux HPS I got when I only had the 1000w MH ballast and it cost me $170 5 or 6 years ago and retails now in Canada for $300. Big as a football and barely fit in my reflector but my light meter pegs it way higher than any other 1000w bulb i have.

Standard bulb next to it. That's an 18" ruler too. The one on the left gives MH light from an HPS ballast. The big one does the reverse and has the ignitor built into the bulb so it can run off the MH ballast which doesn't have the needed ignitor..

View attachment 4944746

Click to expand...

Ah... I was thinking of the 600w.... way cheaper and just all round better.

An alternative might be to go for cmh... perfect for the whole grow and way more efficient. Cmh lights are the best on the market... and up there with led for quality output

oill said:

Ah... I was thinking of the 600w.... way cheaper and just all round better.

An alternative might be to go for cmh... perfect for the whole grow and way more efficient. Cmh lights are the best on the market... and up there with led for quality output

Click to expand...

Ever run a cmh?

Why make things complicated? Just buy a digital ballast that runs both HPS and MH for $100.

xtsho said:

Why make things complicated? Just buy a digital ballast that runs both HPS and MH for $100.

Click to expand...

When he already has a ballast $5 for a switch is a better deal tho. Not all bulbs meant for mag ballasts will work with digital ones and even if they do they usually have a shorter life. I only use my 1000w when the room is full of plants and one 600w on the light rail isn't enough for them.

Something to be said for the sense of satisfaction one gets from a DIY job that works too.

oill said:

Why? There are mh bulbs that fit hps fittings!

Click to expand...

It's not the ceramic socket I'm worried about. MH and HPS lights use a different type of ballast.

xtsho said:

Why make things complicated? Just buy a digital ballast that runs both HPS and MH for $100.

Click to expand...

That would have been my first choice too, but they are only available in 250 watt size or bigger. Too big for what I am doing, I'm using a combination of three 150 watt lights.

OldMedUser said:

Something to be said for the sense of satisfaction one gets from a DIY job that works too.

Click to expand...

Ain't that the truth!

OldMedUser said:

When he already has a ballast $5 for a switch is a better deal tho. Not all bulbs meant for mag ballasts will work with digital ones and even if they do they usually have a shorter life. I only use my 1000w when the room is full of plants and one 600w on the light rail isn't enough for them.

Something to be said for the sense of satisfaction one gets from a DIY job that works too.

Click to expand...

I'm a DIY guy myself. Was just pointing out an inexpensive plug and play setup.

T.H.Cammo said:

That would have been my first choice too, but they are only available in 250 watt size or bigger. Too big for what I am doing, I'm using a combination of three 150 watt lights.

Click to expand...

That changes things. I guess you'll have to wire something up.

DarkWeb said:

Ever run a cmh?

Click to expand...

Yes I have run a 315w cmh.... its amazing. Produces quality that is up there with my hlg leds. Just such an easy light for the whole grow. Doesn't produce much heat either compared to a 600w hps.... and the results are better. If I coukd buy everything again I woukd probably just get cmh... and save a packet on all the led's..... but the leds are amazing too

oill said:

Yes I have run a 315w cmh.... its amazing. Produces quality that is up there with my hlg leds. Just such an easy light for the whole grow. Doesn't produce much heat either compared to a 600w hps.... and the results are better. If I coukd buy everything again I woukd probably just get cmh... and save a packet on all the led's..... but the leds are amazing too

Click to expand...

So have I. I thought it was ok. I wasn't amazed but it was decent. I can't see it comparing to a 600....400 maybe. After a few runs I ended up running the 315 and a 400 together.

DarkWeb said:

So have I. I thought it was ok. I wasn't amazed but it was decent. I can't see it comparing to a 600....400 maybe. After a few runs I ended up running the 315 and a 400 together.

Click to expand...

I run mine alongside my leds in winter. Plants need lollipopping just like a led grow.

oill said:

Yes I have run a 315w cmh.... its amazing. Produces quality that is up there with my hlg leds. Just such an easy light for the whole grow. Doesn't produce much heat either compared to a 600w hps.... and the results are better. If I coukd buy everything again I woukd probably just get cmh... and save a packet on all the led's..... but the leds are amazing too

Click to expand...

I have a 400w Philips CMH that runs off my old hps ballasts. Both my plants and myself like it just fine! Philips doesn't make them anymore tho but there's someone else that does. I have 3 - 600 digi ballasts and a good MH for it and 4 Hortilux SHPS bulbs so have a good selection of sizes to fit the grows. Have a light rail too so can get more coverage out of one light instead of going up to a bigger bulb.