Wattage Question

[MOTAvation]

Could a 270w hps bulb be used in a 250w hps ballast?

[Stix]

Don't know for sure. But it's never a good idea to mix wattages in HID lights unless the manufactuer specifies its ok. There is a real explosion/fire hazard doing so. I wouldn't take anyone's word for it except the manufactuer.

[Racefan]

Originally Posted by MOTAvation

Could a 270w hps bulb be used in a 250w hps ballast?

This is a tough one....a while back they used to make a 400 watt HPS and a 430 watt HPS and we regularly interchanged the bulbs between ballasts without a problem. My gut tells me the wattage isn't enough to make a difference. But that's my gut and not yours.

[Stormycirca65]

Mota, use the bulb as long as the fit in the socket is good. Those differences are well within tolerances for both the ballast and the higher wattage bulb.

[MOTAvation]

Thanks for your replys, but im not using the bulbs.Im not confortable using them even though its just a little wattage over.
Anyone know where i can get some 250w bulbs online?

[Hightide805]

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[Hardope]

With the low watt bulbs theres less chance of fire or poppin the bulb. It will be very easy to find a 250W HPS aslong as its mogel based. Next time the light isnt being used try to pawn it off to a bud and get yourself a 400W M/H for vegging then get yourself a 360W M/H conversion bulb that can be run on the same balasts. Basically giving you 2 lights for vegging and budding in the same light.

[gio77]

Mota, agree with hardope. If the wattage requirement of the bulb is higher than the rated capacity of the ballast, the only harm you run is the possibility of the bulb not initially firing and/or lower total lumens produced while running. If the situation were reversed, the biggest problem you will run across is the bulb burning out sooner rather than later, and possible lumen maintenance over time. Neither will blow-up and/or take fire. Now, if you put a 400 bulb into a 1000 ballast, then I would stand back just in case. Best.

[Stix]

This subject got me wondering exactly what the risk may be so I did a little research. Here's what I found so far.

While incadescent bulbs (standard bulbs) draw current depending on the size of the filament. HID bulbs are force fed there current. Meaning, the ballasts feeds the bulb a set amount of current no matter what size bulb you have in the socket. For example, If you put a 400 watt bulb in a 1000 watt fixture the 400 watt bulb will receive 1000 watts of current when it's only designed for 400 watts. The result would be a bulb that burns out much quicker. Explosion is possible. If you use a 1000 watt bulb with a 400 watt ballast your result will be a bulb only getting fed 400 watts of current resulting in a very dim bulb if it even fired or stayed lit at all. Risk of explosion is minimal.

Explosion isn't necessarily a high risk with HPS lights as it is with MH.

MH bulbs are very dangerous under similar circumstances.

HPS fixtures have the same open circuit voltages no matter what wattage fixture you use.
MH fixtures have different open circuit voltages for different wattages
For example: a 250 watt fixture has a higher open circuit voltage then that of a 400 watt. Therefore, if you used a 400 watt MH bulb with a 250 MH ballast you run the risk of the arc tube rupturing.

As long as you keep your wattages pretty close you will be fine to use a higher wattage bulb with a lower wattage ballast if its HPS.

[MOTAvation]

Thank you guys for your advice, but im going to use the 250w bulbs i dont want to risk anything happening.Maybe ill use them when my 250s go out.