MH Ballast
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tizzo
Guest
Are you sure sign guy?? Cause I alway thought a ballst could light any bulb under and up to it's own wattage. I could put 175 watts in my 250 ballst if I needed to...
kogle
Member
I can speak from very recent personal experience (less than 10 hours ago) if you use a 400 watt ballast and capacitor to fire a 250 bulb it fires instnatly and burns really brightly and by really I mean "Wow, that's too bright for some reason"
I figured out what had happened and fixed it but judging by how fast this bulb fired and how bright it was it might not be a good idea...
Just my $.02
I figured out what had happened and fixed it but judging by how fast this bulb fired and how bright it was it might not be a good idea...
Just my $.02
reefforbrains
Active Member
Originally Posted by KOgle
...... it fires instnatly and burns really brightly and by really I mean "Wow, that's too bright for some reason"
Thats a keeper.......
...... it fires instnatly and burns really brightly and by really I mean "Wow, that's too bright for some reason"
Thats a keeper.......
stanlalee
Active Member
Originally Posted by Tizzo
Are you sure sign guy?? Cause I alway thought a ballst could light any bulb under and up to it's own wattage. I could put 175 watts in my 250 ballst if I needed to...
you could try but there is but so much a bulb can be overdriven before you into heat/reliability problems. it may explode and wil certainly not last as long as it should. I've heard of people running 150w bulbs on 175w ballast and many 400w labelled magnetic ballast are actually 430w grow light ballast but other than that I have never heard of anybody overdrivng MH any more than that.
Driving two 175w bulbs with a true 400w ballast is only overdriving each bulb 25watts which is inline with the few examples sometimes done but I have no idea the correct way to attempt wiring it. I assume you would just wire the two sockets in parallel and hope for the best
Are you sure sign guy?? Cause I alway thought a ballst could light any bulb under and up to it's own wattage. I could put 175 watts in my 250 ballst if I needed to...
you could try but there is but so much a bulb can be overdriven before you into heat/reliability problems. it may explode and wil certainly not last as long as it should. I've heard of people running 150w bulbs on 175w ballast and many 400w labelled magnetic ballast are actually 430w grow light ballast but other than that I have never heard of anybody overdrivng MH any more than that.
Driving two 175w bulbs with a true 400w ballast is only overdriving each bulb 25watts which is inline with the few examples sometimes done but I have no idea the correct way to attempt wiring it. I assume you would just wire the two sockets in parallel and hope for the best
scsinet
Active Member
Originally Posted by Stanlalee
Driving two 175w bulbs with a true 400w ballast is only overdriving each bulb 25watts which is inline with the few examples sometimes done but I have no idea the correct way to attempt wiring it. I assume you would just wire the two sockets in parallel and hope for the best
I can't see it working...
Halide lamps use an arc to produce light. Arcing, unlike resistive heating (what incandescent lights use) will draw power essentially infinitely. The only way to keep the arc under control is to limit the amount of current it is allowed to consume. This is the job of the ballast.
If you were to connect two lamps in parallel, most likely, only one lamp would light. The reason for that is that the high voltage kick produced by the ballast to ionize the halides in the arc tube and strike the arc would not kick across both arc tubes at once, only the one that has slighly less resistance due to slightly different temperatures, manufacturing tolerances, etc. Even if you somehow got an arc struck in both lamps, one lamp would hog all of the current, causing the second lamp's arc to quench and thus shutting down both lamps.
It's a huge risk to undertake with 80 dollar lamps, let alone the fire risk if that capacitor in the ballast explodes (which is entirely possible). You can get plain magnetic ballasts on that famous site where you bid on stuff for $25-40 each... seems worth it to get the right ones.
Driving two 175w bulbs with a true 400w ballast is only overdriving each bulb 25watts which is inline with the few examples sometimes done but I have no idea the correct way to attempt wiring it. I assume you would just wire the two sockets in parallel and hope for the best
I can't see it working...
Halide lamps use an arc to produce light. Arcing, unlike resistive heating (what incandescent lights use) will draw power essentially infinitely. The only way to keep the arc under control is to limit the amount of current it is allowed to consume. This is the job of the ballast.
If you were to connect two lamps in parallel, most likely, only one lamp would light. The reason for that is that the high voltage kick produced by the ballast to ionize the halides in the arc tube and strike the arc would not kick across both arc tubes at once, only the one that has slighly less resistance due to slightly different temperatures, manufacturing tolerances, etc. Even if you somehow got an arc struck in both lamps, one lamp would hog all of the current, causing the second lamp's arc to quench and thus shutting down both lamps.
It's a huge risk to undertake with 80 dollar lamps, let alone the fire risk if that capacitor in the ballast explodes (which is entirely possible). You can get plain magnetic ballasts on that famous site where you bid on stuff for $25-40 each... seems worth it to get the right ones.
trainfever
Active Member
what if you were to wire two 175s, or two 250s in series and then used a 400 watt ballast to light them, would it work?
scsinet
Active Member
Originally Posted by trainfever
what if you were to wire two 175s, or two 250s in series and then used a 400 watt ballast to light them, would it work?
Still no, for a somewhat different reason. The different bulb sizes use more or less the same voltage to run the lamp, so running two in series would cause the ballast to deliver half voltage to each lamp, which at the regulated current would not be sufficient to maintain an arc. Plus, the ignition problem described above would still exist.
Theoretically, I can see a double bulb arrangement possible, but not out of the box. From an engineering standpoint, I'd try it by connecting two probe-start ignitors off of the ballast, then from each of those, a power resistor, then each lamp, then common each lamp back off to neutral. This would allow the lamps to play nice with current, and the separate ignitors would fire each lamp independently. However, this design has 3 major flaws. First, all the ignitors and resistors cost money, up to and including what new 175w ballasts would have cost anyway. Second, If one bulb goes bad or extinguishes for some other reason, it would cause the current to fly through the roof to the operating lamp, which would cause very rapid demise of the second lamp, the ballast, or both. Third, I've never attempted actually building something like this so I have no clue as to whether or not it actually would work (sounds cool though.. huh?).
what if you were to wire two 175s, or two 250s in series and then used a 400 watt ballast to light them, would it work?
Still no, for a somewhat different reason. The different bulb sizes use more or less the same voltage to run the lamp, so running two in series would cause the ballast to deliver half voltage to each lamp, which at the regulated current would not be sufficient to maintain an arc. Plus, the ignition problem described above would still exist.
Theoretically, I can see a double bulb arrangement possible, but not out of the box. From an engineering standpoint, I'd try it by connecting two probe-start ignitors off of the ballast, then from each of those, a power resistor, then each lamp, then common each lamp back off to neutral. This would allow the lamps to play nice with current, and the separate ignitors would fire each lamp independently. However, this design has 3 major flaws. First, all the ignitors and resistors cost money, up to and including what new 175w ballasts would have cost anyway. Second, If one bulb goes bad or extinguishes for some other reason, it would cause the current to fly through the roof to the operating lamp, which would cause very rapid demise of the second lamp, the ballast, or both. Third, I've never attempted actually building something like this so I have no clue as to whether or not it actually would work (sounds cool though.. huh?).