F25T8 Magnetic Preheat Ballast « on: October 17, 2025, 09:34:50 PM » Author: NeXe Lights
I am looking for a single lamp F25T8 preheat ballast for my GE F25T8 undercabinet fixture. I am not sure if these even exist quite frankly. The ballast should be the exact same size or a very similar size to the Keystone KTEB-126-1-TP-LC electronic rapid start ballast. This ballast is 6.46 inches long, 1.89 inches wide and 1.15 inches tall. This ballast makes use of 6 inch mounting. If such a preheat ballast does not exist, I would like a program rapid start ballast instead so I atleast get some preheat action still.
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“Beware the barrenness of a busy life.” Socrates

	Re: F25T8 Magnetic Preheat Ballast « Reply #1 on: October 17, 2025, 09:40:54 PM » Author: WorldwideHIDCollectorUSA
Even though I have seen no evidence of magnetic F25T8 preheat fluorescent ballasts being manufactured, I have seen that some other collectors have ran F25T8 fluorescent tubes just fine in F30T8 preheat fluorescent fixtures with the tubes being overdriven a bit. I think this is probably okay because even though the F25T8 tubes are overdriven, they will probably still outlast properly driven F30T8 tubes because while F25T8 tubes seem to have a rated lifetime of 30,000 hours, F30T8 tubes seem to have a rated lifetime of only 7500 hours.
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Desire to collect various light bulbs (especially HID), control gear, and fixtures from around the world.

DISCLAIMER: THE EXPERIMENTS THAT I CONDUCT INVOLVING UNUSUAL LAMP/BALLAST COMBINATIONS SHOULD NOT BE ATTEMPTED UNLESS YOU HAVE THE PROPER KNOWLEDGE. I AM NOT RESPONSIBLE FOR ANY INJURIES.

	Re: F25T8 Magnetic Preheat Ballast « Reply #2 on: October 17, 2025, 09:44:20 PM » Author: NeXe Lights
OK. In that case, I'll just find a program rapid start electronic ballast that will fit in this fixture.
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“Beware the barrenness of a busy life.” Socrates

	Re: F25T8 Magnetic Preheat Ballast « Reply #3 on: October 17, 2025, 09:46:25 PM » Author: WorldwideHIDCollectorUSA
In case you were wondering, here is the evidence of one of our collectors running F25T8 tubes in a F30T8 preheat fluorescent fixture: https://www.lighting-gallery.net/gallery/displayimage.php?album=search&cat=0&pos=7&pid=114438
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Desire to collect various light bulbs (especially HID), control gear, and fixtures from around the world.

DISCLAIMER: THE EXPERIMENTS THAT I CONDUCT INVOLVING UNUSUAL LAMP/BALLAST COMBINATIONS SHOULD NOT BE ATTEMPTED UNLESS YOU HAVE THE PROPER KNOWLEDGE. I AM NOT RESPONSIBLE FOR ANY INJURIES.

	Re: F25T8 Magnetic Preheat Ballast « Reply #5 on: October 21, 2025, 07:45:51 PM » Author: WorldwideHIDCollectorUSA
Interestingly, I am also aware that F30T8 tubes were one of the first sizes of fluorescent tubes ever manufactured. In a late 1930s brochure, they do mention that a F30T8 tube is not compatible with a 110-120V lighting circuit and that a 1 to 2 ratio step up transformer is required unless 220-240V circuits are available. I am aware that this was before autotransformer ballasts were made. After autotransformer ballasts were made for these tubes, this enabled them to run on 110-120V circuits.
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Desire to collect various light bulbs (especially HID), control gear, and fixtures from around the world.

DISCLAIMER: THE EXPERIMENTS THAT I CONDUCT INVOLVING UNUSUAL LAMP/BALLAST COMBINATIONS SHOULD NOT BE ATTEMPTED UNLESS YOU HAVE THE PROPER KNOWLEDGE. I AM NOT RESPONSIBLE FOR ANY INJURIES.