Hello everyone,

I am new to this forum. I have been visiting for some time and finally decided to join. 

I have a 15 watt 18 inch undercabinet GE fixture with a hardwired glowbottle starter and a GE-branded chinese UCF-EM-15-S-TY core-and-coil ballast. The starter got stuck and the fixture operated like this for about 12 hours. The ballast then failed open (I wasn't there to see it happen). The lamp is still good despite heavy end blackening, but the ballast does not work at all, no hum, no light. I tested it with a continuity tester and no current passes through. I suspect the thermal fuse has blown. Any thoughts on this ? I know one should replace spent lamps and starters promptly, but 12 hours and a burnt thermal fuse seems a bit short-lived and on the disposable side of things.  Is this normal ? I have seen many stuck starters for long periods of time and the ballasts still work once relamped and restartered.

I found some similar undercabinet fixtures made by GE with similar ballasts but the starters were replaceable. In both cases the ballasts didnt work. I opened them up and clipped out the thermal protectors, which I think were of the non resetting variety, and twisted the wires where the protectors were together and they worked again. However, they are no longer thermally protected, and also if you twist the wrong wires, you can short the ballast and that can cause much greater problems later and could be potentially dangerous so you should be very sure you know what you are doing if you try that route. I found the thermal units by unwrapping the blue tape. I should also mention that you want to be careful not to stick that tape to anything else until you put it back on or it might have trouble sticking again, and be sure to wrap it very tightly when retaping it. I suppose if you were concerned enough, you could buy a resetting thermal protector and wire it with the ballast and place it right against the ballast as a safety measure, but these small choke type preheat ballasts rarely overheat. It can happen, but it doesn't happen as often as instant start or rapid start ballasts overheating. Again, if you try what I did on your ballast, you should be VERY sure you know what you are doing. Hopefully this was helpful.

The excessive dissipation associated with stuck starter would overheat every ballast. In your case it was not much problem of 12 hours cumulative, but more then ~1/2hour at once.

With this experience i would never ever bypass the thermal protection, it would be really asking for fire in your way of operation (long time unsupervised).

Way better is to use there resettable protection (best with manual reset), what would keep the fixture operating after such event and still avoid ballast destruction.
Technically great would be the use of PTC-based resetable (after tripping it will maintain itself on the "OFF" temperature, so as protection it would be reset by only cycling the power), but these are a bit tricky to dimension well (their tripping current and surrounding temperature are strongly dependent on each other)
Such protection would even avoid excessive wear on lamp electrodes in the "stuck starter" fault.

Thank you DaveMan and Medved. Unfortunately, I do not have time for such a repair, but I will print out this post and store it with the ballast for future use. I have a chinese E4819-B-P Class P ballast that I will use as a replacement (along with a new starter). Hopefully it will work longer.

i have the same fixture at the shop.
missing diffuser and a buzzy ballast.stuch it on the underside of my workbench to aid in finding dropped parts and stuff stored under there.fine for intermittant use but i would have to shoot it if i had to use it all day!
hey at least they are protected from burning out.i would rather it die quietly instead of filling the shop with nasty smoke like that sunpark pos did!

Yep, thermal protection is a good thing .. burnt ballast smells really bad