# Multiple Hps Bulbs in Parrallel to Single Ballast



## potlike (Sep 12, 2007)

While I am definitely a diy'r and have wired several electrical outlets, my understanding of electricity is limited. Was wondering if instead of one 600w bulb if I was to use 4 150w in parallel to a single 600w digital ballast if that would work? The idea would be to get better light penetration and with cool tubes around each one more usable lumens over the entire grow area as there would be a more even distribution of light. Let me know.


-pot


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## potlike (Sep 13, 2007)

bump

any electricians in the house?

-pot


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## kindprincess (Sep 13, 2007)

i wouldnt' try it; the bulbs are rated for individual transformer sizes. i play with electricity a bit, but this can kill you if it doesn't work right. do you really want to take the chance?

kp


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## 000420 (Sep 13, 2007)

no it won't work, for a few reasons and it would be dangerous, one thing is the ignitor in a 600 watt ballast would not strike all 4 bulbs, you would need 4 ignitors made for 150 watt bulbs and one for each bulb......I can go on if you want with other reasons but only if you want...i'm to stoned to type..and yes i'm an electrician and a tv repair man


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## FilthyFletch (Sep 13, 2007)

Id say probably not as the hps igniter may be to much and would probably pop the first bulb before even going through the entire chain. If you try it post back and let use know if it works or if your in the hospital lolCreative thinking though


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## potlike (Sep 13, 2007)

appreciate the answer guys... I've just played a little bit with electrical wiring and never done anything major as I don't know all of the theory behind it, and that is a dangerous thing to do. I am considering making 4 diy 150w ballast then and maybe selling my 600w any takers?  I've done some math and you can keep the 150 watts less than 6 inches away and that compared to 2 feet away with one 600watter is MORE efficient.

-pot


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## ryan2clw (Oct 14, 2014)

I have a degree in electrical engineering. This should help:
Assuming that the 150 (W) bulbs have 1/4 of the resistance compared to the 600(W) bulb, you would need to run them in series. In series circuits, you add the resistances. If you run things in parallel, you're going to lower the equivalent resistance, because there are more paths for the electricity to travel. If you ran it parallel you would have 16 times more current than you intended and things would go fizzle and boom.


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## Flagg420 (Oct 14, 2014)

the thing is, dropping ur wattage that low, u may as well be running CFL's.... We use HIDs for the powerful light penetration.... ur not gonna get that w/ 150w.... meaning only the top 3inches of your plants are getting enough light.... I wouldn't drop below 250w on an hps bulb, feels.... wasteful... just my $0.02


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## Midwest Weedist (Oct 18, 2014)

Why 150 watt bulbs? At least aim for 250 if you're going to try and run them in a series for the light penetration. I have a 150 watt hps and the penetration isn't shit compared to a 250 or higher. I may be wrong on this, but wouldn't it also cost more to run that many bulbs over 1?


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## butterbudface (Oct 23, 2014)

not gonna work caps to small and ignition wont fire all 4 like someone said earlier. There are other ways.... but they are complicated.


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## 000420 (Oct 28, 2014)

ryan2clw said:


> I have a degree in electrical engineering. This should help:
> Assuming that the 150 (W) bulbs have 1/4 of the resistance compared to the 600(W) bulb, you would need to run them in series. In series circuits, you add the resistances. If you run things in parallel, you're going to lower the equivalent resistance, because there are more paths for the electricity to travel. If you ran it parallel you would have 16 times more current than you intended and things would go fizzle and boom.


Actually that does not apply in this case. HPS lamps are gas discharge lamps which exhibit negative differential resistance when operating which is why they require a ballast, to limit the current through the ionized gas.


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## dehv (Mar 13, 2019)

butterbudface said:


> not gonna work caps to small and ignition wont fire all 4 like someone said earlier. There are other ways.... but they are complicated.


so looking at this:





Which is a 400W MH SYLVANIA 67811

I would assume it is 2x200W bulbs in parallel struck by the single (ext) igniter.

So to run 4x150's on a 600 - if the cap was PF correcting in parallel the cap value should be ok in parallel.... and what if you just wired up 4 separate starters one for each 150w bulb?


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## dehv (Mar 13, 2019)

in my case i just ordered a dozen 70W Hps bulbs, and have a couple new 150W Hps ballast kits with starters/caps.

So i was thinking 2 (with their own starters after the ballast) in parallel with the ballast, to match the same value cap as 150W (14uF). 

Or maybe single 7uFs on each 70w bulb/starter combo?


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## Schwagg#12 (Mar 13, 2019)




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## growingforfun (Mar 13, 2019)

Grow the fuck up and use a 1kw bulb.

What's with the new wave of grower trying to make things so hard and reinvent the wheel? Yes I realize this is a old thread but I mean this both in general and at the person who bumped it.

Jesus growing erb shouldnt be complicated it should be relaxing. Dont risk burning your house down or killing yourself.


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## dehv (Mar 13, 2019)

In this case it's a "use what you got" theoretical more than practical question. Or should I be a big boy and stroke your 1000w cock I can't afford when I have brand new equipment sitting here?

The worst that could happen is it doesn't work, we're not talking about overdriving here. Besides, there's one youtube where a guy overdrives a 70w mercury vapor to some 3000W before it pops (inside the outer bulb).

Like the OP said, why burn your plants or waste light because you have to keep them farther away, when you could use more small lamps and distribute the light evenly over a given area - in this case FOR FREE???


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## growingforfun (Mar 13, 2019)

dehv said:


> In this case it's a "use what you got" theoretical more than practical question. Or should I be a big boy and stroke your 1000w cock I can't afford when I have brand new equipment sitting here?
> 
> The worst that could happen is it doesn't work, we're not talking about overdriving here. Besides, there's one youtube where a guy overdrives a 70w mercury vapor to some 3000W before it pops (inside the outer bulb).
> 
> Like the OP said, why burn your plants or waste light because you have to keep them farther away, when you could use more small lamps and distribute the light evenly over a given area - in this case FOR FREE???


In your case.... just dont grow. If you cant afford the 30 bucks a month the 1kw costs to run, or the 150$-300$ depending on model.... just dont do it. Growing erb isnt for children. Gotta be over 18 to use the forum buddy. Please dont burn your parents house down or something like that.


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## dehv (Mar 13, 2019)

Funny, thanks for your constructive input. I'll leave the growing to you "expert priest types", who apparently are better at growing "erb" and thinking inside the hotbox than everyone else I suppose.

Oh wait! I'm already growing and don't give a fuck what you're smoking - I was just trying to have a theoretical conversation before you brought all this negativity to the thread.


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## growingforfun (Mar 13, 2019)

dehv said:


> Funny, thanks for your constructive input. I'll leave the growing to you "expert priest types", who apparently are better at growing "erb" and thinking inside the hotbox than everyone else I suppose.
> 
> Oh wait! I'm already growing and don't give a fuck what you're smoking - I was just trying to have a theoretical conversation before you brought all this negativity to the thread.


Please keep several smoke alarms all over your house and many fire extinguishers handy. Dont be afraid to just run outside and let it burn. 

#thoughtsandprayers
#nostupidquestionsonlystupidpeople


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## dehv (Mar 14, 2019)

growingforfun said:


> Please keep several smoke alarms all over your house and many fire extinguishers handy. Dont be afraid to just run outside and let it burn.
> 
> #thoughtsandprayers
> #nostupidquestionsonlystupidpeople


Of course, don't forget the smoke alarm superglued to your bald spot - for when the knob and tube in your brain starts what's left of your grey hair on fire.
#thoughtcrimes #1984joke #feedthetrolls #jerkthepriest

Regarding the actual topic at hand, series wouldn't work because of the mentioned above resistance pre-arc, but parallel in theory should work with single igniter. Check the power factor is >0.9 and capacitors are matched.


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## dehv (Mar 14, 2019)

I could see improperly matched capacitors causing poor power factor and increased heat in the ballast. Some examples I've found when it comes to HPS in particular:
7uF (MFD) - 70W
14uf - 150w
and so on up to 55uF for 400w


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## xtsho (Mar 14, 2019)

70 watt HPS? Why bother?. Why not just use the right wattage for your ballast? You want more light intensity not less.


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## dehv (Mar 14, 2019)

for seedlings and clones, or to use lights in the garage perhaps? 

again - THEORETICALLY.


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## Renfro (Mar 14, 2019)

I have seen splitters that are designed for this. Dunno what to think about them, seems like a discontinued product. Probably a good reason.

https://www.planetnatural.com/product/ballast-splitter/


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## Renfro (Mar 14, 2019)

Thats a different one, supposed to work with digital ballasts

https://growershouse.com/solis-tek-digital-splitter


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## Renfro (Mar 14, 2019)

FWIW an old thread on the matter

https://www.rollitup.org/t/using-one-ballast-to-run-two-lights.735286/page-2


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## Renfro (Mar 14, 2019)

I was considering using one 1kW HPS ballast running at 1200 watt overdrive to run two 630W CMH bulbs but the more I research it doesn't seem like a good idea.

What if one bulb goes out, would all 1200 watts go to the remaining bulb and toast it too?


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## dehv (Mar 14, 2019)

Renfro said:


> I was considering using one 1kW HPS ballast running at 1200 watt overdrive to run two 630W CMH bulbs but the more I research it doesn't seem like a good idea.
> 
> What if one bulb goes out, would all 1200 watts go to the remaining bulb and toast it too?


Aha! finally a good point! Yes the ballast would provide the full amount of current to whatever it was powering.

To clarify, I'm speaking specifically regarding magnetic ballasts for simplification of discussion.

Having looked over that old thread (thank you!) it seems there is some confusion regarding ohms law on that thread (mostly relating to digital ballasts), but that doesn't apply because:

"HID lamps have negative impedance, which means that the lamp draws more current than is required for it to operate." - Source: 5024_HID_Ballast_Application_Guide

So in my example of 2x70s on a 150 mag ballast - if one dies the other would use the entire current available from the ballast, worst case creating a shit power factor and/or burning out the internal bulb. 

BUT in the OP's case, 4x150s, sounds like an even sketchier idea. They couldn't be run in series because that's for splitting the voltage where here we would want to be sharing the current (of the ballast) at the same voltage.

Interesting thought experiment, I'll have to give it a (temporary) whirl on the bench and see.


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## dandruff (May 1, 2019)

dehv said:


> In this case it's a "use what you got" theoretical more than practical question. Or should I be a big boy and stroke your 1000w cock I can't afford when I have brand new equipment sitting here?
> 
> The worst that could happen is it doesn't work, we're not talking about overdriving here. Besides, there's one youtube where a guy overdrives a 70w mercury vapor to some 3000W before it pops (inside the outer bulb).
> 
> Like the OP said, why burn your plants or waste light because you have to keep them farther away, when you could use more small lamps and distribute the light evenly over a given area - in this case FOR FREE???


If you can't afford a 1kw lamp you should delay your hobby until you can, or get the bread to buy one. Besides, sometimes there are arising circumstances that happen that call for more $$$ to be spent than a 1kw lamp setup is worth. You need to get your priorities straight bud.


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