I have an f40t12 fixture that has a bad ballast. The existing ballast has blk and wht wires along with 2 blues and a red. The red goes to one tombstone on the right side and a jumper goes over to the other. The 2 blues go to the left tombstones, one to each.

Here's my confusion. The replacement ballast has blk & wht, plus 2 reds, 2 blues and 2 yellows. The wiring diagram shows the 2 reds going to the first tombstone on the right and the 2 blues going to the other tombstone on the right. The 2 yellows go to one each of the left hand tombstones and then jumpers between those two so each yellow in effect goes to both tombstones.

Why are there so many different wiring options for electronic ballast? Do I need to wire it exactly as the diagram shows, pulling all existing wires from the tombstones and inserting the new wires or is there a simpler way? Thanks

I certainly don't understand fluorescent fixtures!

 

Yes, you need to change the wiring so it looks exactly like the diagram on the ballast.

 

You could convert that fixture to use T-8 lamps with a T-8 ballast and then there would be no wiring changes needed.

Two T-8 tubes ballast wiring.

 

Thanks, I will look at the T8 solution.

 

T-12 are being phased out.

 

I just use LED tubes that connect directly to power in and junk the ballasts. About the same price as tubes and ballast if the LEDs are bought at places like Amazon.

 

The 4 foot T12 lamps the OP currently has have not been manufactured in over 3 years. They are still available at the big box stores, but have gotten pretty expensive for an obsolete product.

Ray makes an excellent point. Rather than retrofit, it may be wiser to go to the LED replacement for the 4 foot fluorescent lamp. The only one I am aware of that was recalled was the one from Cree. You can expect these to cost roughly $22 to $25 each at a big box, not sure what they cost through Amazon.

 

I paid $18 at Amazon. I think there were others a dollar or two cheaper but two at $18 is $36 and Amazon has free shipping for $35 and over.

 

How do you use the LED bulbs? Just short around the ballast?

 

Some LEDs can actually be connected to the ballast but given the cost of ballasts and the likelihood of failure that to me isn't the best way. Others you just connect the 120 volts to the tombstones and sell the ballast for scrap.

Some like the ones I bought can be connected to either the ballast or straight to the 120v in. The ones I bought neutral goes to one end of the tube and hot to the other end of the tubes. Basically I cut the wires from the tombstones at the ballast and connected all the tombstone wires on one end to black and all the ones on the other end to white. (I didn't need to use all the wires but no harm doing so and I didn't have to bother with sorting out and removing unneeded wires.)

It should be noted on some though the black and white connect to the same end and the other end is a dummy lamp holder with no power. In the single end type black to one pin and white to the other pin. T-8 may have internally shorted tombstones so with this type the tombstones would have to be replaced.

Bottom line in my opinion look for one that connects directly to both ends on the tube. That will work with whatever the existing tombstones are and is simple to wire..

 

I am not at all familiar with those LED lamps, but I do like the idea of trashing the ballast.

 

Been there done that on a T-12 with a failing ballast and old tubes so from experience I pontificate.

 

Ray, do you ride around in the Popemobile when you pontificate ?

 

No, but I helped wire it.