Originally Posted by fishstein
I'm hoping someone out there can tell me why one of my endcaps "flashed" - the plastic/rubber partially melted to the end of the T8 bulb and scorched the inside of my wooden tank hood a few months ago; and then another end cap started to burn/melt today - I suddenly smelled burning plastic/rubber and noticed it was coming from the hood - and then pulled the power. The heat was high enough on that endcap to partially melt it, burn a hole through the side and fuse it to the end of the bulb.
I suspect that the culprit is either 1) age - that either the endcaps needs to be replaced after many years use or the ballasts need to be replaced OR 2) the ballasts not being able to handle the combination of one bulb at F32 Watt and one bulb at F36 Watt 3) old electronic ballasts that need to be replaced.
I've had these endcaps and electronic ballasts in continuous daily use for about 8 years. Perhaps the endcaps become dry and more vulnerable to heat over time. I do have replacement endcaps on hand, but before I use them I'd like to find out what the cause is.
Currently I'm using the best bulb combination I've ever used - each ballast is running 2 bulbs, one Phillips Aquarelle TL89 F36T8 10,000K one Phillips Advantage F32 ADV850 5000K bulb, for a total of 4 48 inch T8 bulbs in the hood. The hood is well ventilated.
Some possibly important clues:
1) The endcaps that have fried are both on the right side of the aquarium feeding off of the red (hot) white and black wires from the ballasts (the endcaps on the other side where there was no meltdown feed off the blue wires coming from the ballasts).
2) Also, the first fried endcap was on an Aquarelle bulb; the second one today was on an ADV850. So I'm not sure if it's the bulbs. Perhaps it's the combination of the 36 Watt (Aquarelle) and the 32 Watt (ADV850) on the same ballast.
3) The first endcap to fry was fed by one ballast; the endcap that fried today is fed by the other ballast.
I'd sincerely appreciate your advice - not just for the health of my tank, but for the safety of my family and other pets!
It's not a good idea to drive two unbalanced loads with one ballast. I'd change the electronic ballast and check all wiring. Pay attention to age and moisture. Check for good isolation between the driving elements and ground. Most electronic ballast are designed to drive 32 Watt 4' T8.