drdawg said:Does the doubling of the ballasts cause them to heat?
The bulbs are noticeably warmer, but not what I would call hot. However, a zinnia that grows into direct contact with an overdriven bulb gets fried in the contact area. But they sort of do that with direct contact to regular T8 bulbs.
The overdriven ballasts actually run significantly cooler. That is because they are connected to significantly less load in a single bulb as compared to the load of two bulbs. If anything, the overdriving ballasts last longer, besides running significantly cooler.
You make T-5HO fixtures and bulbs sound quite attractive. If I were just starting out with indoor gardening, I would definitely consider using them. But I now have several dozen T8 shoplights, and they were quite economical to procure (back in the early 2003 - 2004 time frame, Home Depot was selling 2-bulb T8 shoplights for $4 each (without bulbs).) I think that was a loss leader to introduce their Chinese-made shoplights.
The irony of that was that their SunPark SL15 electronic ballasts were selling for more than that. So, in the "early days", I would buy 8 T8 shoplights, and cannibalize 4 of them for ballasts to overdrive the other 4.
In later years the shoplight prices went to $6 and then $8 and higher, so it wasn't economical to cannibalize them. I would then buy ballasts to bring those "empty" fixtures into service.
When I "started out", T5 fluorescents were more expensive and Home Depot didn't even stock them, so the bargain T8 shoplights were a natural. And Home Depot was selling boxes of 10 T8 tubes for $18, which was significantly cheaper than those same boxes go for today. Of course, I guess inflation has something to do with that.
ZM
