Q: REGARDING T-8 4 FT LAMPS OVERHEATING

[pinball77]

Hello, was in the store the other day. wife was shopping i was bored as usual. Looked up and saw plastic dripping from one of he 4ft tubes in the store. One of the lamps had failed. this was the 4ft type thinner octron bulbs i believe . the lamps had a plastic cover which was red hot almost on fire where the end of the bulb was as the bulb was failing. I looked at other lamps that were in the store and all had these plastic covers on them. The ones that were burnt out also had melting on the ends . Just wondering if this is normal for these lamps to get that hot upon failure. I know the older t-12s didnt get that hot. jr

[RBM]

From my experience, I've found many fixture sockets don't make good contact when the plastic tube cover ends are used. When this occurs, the arcing causes the ends to melt and the lamps ultimately go out

[ransley]

You should call that store , when they fail they start fires. I have heard of several large fires caused by bad ballasts.

[RBM]

You should call that store , when they fail they start fires. I have heard of several large fires caused by bad ballasts.

Fluorescent ballasts for the last 30 years or so, have had thermal cutouts built into them, to prevent overheating, but prior to that, it was common for them to smolder and smoke

[DanG]

If these are exposed bulbs that could fall to the floor if broken, they have been slid inside a plastic tube to catch the broken stuff. They are more liable to be T5s than T8s. The plastic sleeves must not be quite the right type. If the bulbs are that new, I'm sure they have electronic ballasts, not tar filled magnetics. I am not aware of failure mode crating additional heat.

[pinball77]

surprisingly, these are t8's. the fixtures all look to have been retrofitted from t-12's. They must have the electronic ballasts because the failed lamps are singles and are completely off not flickering like the t-12's did when failed. I just thought the electronic ballasts had some type of overheat protection to shut the fixture down in case of overheating. doesnt seem like the sockets are failing. All lamps have these plastic tubes on them. The failed bulbs have the 3" dark spot on the bulb ends and all of them the plastic is charred or melted /burned away in this area on the tube. Like I said I saw a bulb that was flickering on its way out, tube plastic red hot dripping on the floor. told cashier she was more concerned with her bf on her cell. I Had to catch a movie with wife.

[RBM]

surprisingly, these are t8's. the fixtures all look to have been retrofitted from t-12's. They must have the electronic ballasts because the failed lamps are singles and are completely off not flickering like the t-12's did when failed. I just thought the electronic ballasts had some type of overheat protection to shut the fixture down in case of overheating. doesnt seem like the sockets are failing. All lamps have these plastic tubes on them. The failed bulbs have the 3" dark spot on the bulb ends and all of them the plastic is charred or melted /burned away in this area on the tube. Like I said I saw a bulb that was flickering on its way out, tube plastic red hot dripping on the floor. told cashier she was more concerned with her bf on her cell. I Had to catch a movie with wife.

The electronic ballasts do have thermal protection. It's not the ballast that's overheating.