On 11/2/2016 1:01 AM, Bill Moinihan wrote:
Meanie wrote:

The lamps you have look like T12. That means, according to the LED info,
your LEDs will not reach the 50,000 hours because you are using T12
ballasts.

You are correct.

All 16 of the 4-foot fluorescent bulbs said they were 40 watts, rapid start,
average life 12,000 hours.
https://s18.postimg.org/llp51oemh/01..._t12_bulbs.jpg

Of the four ceiling mounted units, three worked fine either with four
T12/40W fluorescent bulbs or with four T8 LED bulbs.
https://s22.postimg.org/8hx6ech7l/03..._just_fine.jpg

The one ceiling unit that was humming badly had two ballasts inside when I
removed the center covering steel plate:
https://s13.postimg.org/kekhhvot3/04...0_ballasts.jpg

Both ballasts were of the same type, with a sticker on each saying
Universal Therm-o-matic rapid start ballast
For two F40W T12/RS lamps, high power factor
Cat No 446-LR-TC-P, 120V, 60Hertz, 0.8Amp line
Universal Mfg. Corp, Paterson NJ, Made in USA
Class P Automatic resetting thermal protected
https://s11.postimg.org/orqbysecj/02...s_40_W_T12.jpg

Even though only one ballast is humming badly, I found the oddest situation
when I put in either just one known-good fluorescent bulb or just 1 of the
new LED bulbs.

Only one lane worked with just one bulb, which was this lane, which I'll
call lane 2 since it's the second one from the outside:
https://s15.postimg.org/4gu6scm0r/a_...is_working.jpg

But when I put the single bulb in any other lane (leaving the rest of the
lanes empty) the bulb didn't light up (whether it was fluorescent or LED).

Is there any way to tell which two of the four lanes *each* ballast
controls?

Does the one good ballast control the two inside lanes?
https://s17.postimg.org/tk1zfwckv/two_inside_lanes.jpg

Or does one ballast control the two lanes next to each other?
https://s16.postimg.org/uycmzw2wl/tw...each_other.jpg

Or does the one ballast control every other lane?
https://s12.postimg.org/vqlyluwa5/every_other_lane.jpg



A four lamp fixture with two ballasts will operate two lamps each. One
will control the outer lamps and the other will control the inner lamps.
To determine what ballast controls what lamps, you need to follow a wire
to the tombstone (pin) connection of the lamp. For example, follow the
yellow wire to one of the connectors. If it's the inner lamp, then that
ballast controls those two lamps and the other will control the outer two.