F40T12 ballast replacement and rewiring


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Old 12-21-22, 09:30 AM
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F40T12 ballast replacement and rewiring

I need to replace this ballast to use with fluorescent bulbs. Most of what I'm finding seems to be for different bulbs.

Also, Is it ok just to cut and splice the newer wiring in with wire nuts or butt connectors instead of trying to get the receptacle panel off?


 
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Old 12-21-22, 10:41 AM
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I don't understand why you made the comment "seems to be for different bulbs". Did you have a question about that or does it somehow affect your situation? Are you using bulbs not intended for your ballast?

Yes, you can cut and splice the wiring when installing a new ballast.

---
Instead of replacing the ballast I HIGHLY recommend converting to LED. You disconnect or remove the old ballast and install LED bulbs. It's a very simple conversion and usually cheaper than the cost of a replacement ballast. When I converted the fixtures like yours in my office the LED bulbs were brighter so I got about the same illumination using only two bulbs instead of four.
 
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Old 12-21-22, 02:02 PM
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Your old ballast is for T-12 tubes. T-12 stands for 12/8ths of an inch or 1.5" diameter.
T-12's are just about extinct.
The bulk of tubes used now are T-8's. 8/8ths on an inch or 1" diameter.

So if you are using T-8 tubes.... don't use a T-12 ballast.... if you can find one.
As mentioned.... more cost effective to spend the $20 for the ballast on two F-32 LED tubes.
You can use your existing sockets for T-8 bulbs.
 
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Old 12-21-22, 02:59 PM
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Got it.

What I meant was most of the ballasts I saw weren't for T12s but I see from your replies why. We still have many fixtures that use T12 and some that use T8 so I have both bulbs in stock. I'll swap these over to T8 ballasts.
 

Last edited by beedoola; 12-21-22 at 04:41 PM.
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Old 12-21-22, 09:23 PM
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Get rid of the T-12's.
Most of those old ballasts preheated the filament to start the mercury ionizing.
By law the amount of mercury was reduced in all tubes so that the preheat method just barely was able to make the tubes start up. That's why the big tubes start intermittently now.

Today's T-8 ballasts send a high voltage pulse across the ends of the tube. The filament is not heated. That pulse starts the arc. That system works well with the thinner tubes. It doesn't work at all with T-12's
 
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Old 12-22-22, 02:30 AM
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You really should just start converting them over to LED.

Once you convert the first one and see the HUGE improvement to light quality you will never buy another ballast/fluorescent bulb.
 
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Old 12-22-22, 08:09 AM
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What ballast would work with the T8s? I'd need to keep the same wiring config as shown on the ballast in my OP, yes?
 
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Old 12-22-22, 09:01 AM
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would also suggest switching to led where you just bypass or remove the ballast all together if your set on sticking with a ballast would just follow the manufacturers diagram often it is on the ballast or can be looked up if you go the manufacturers website.
 
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Old 12-22-22, 12:26 PM
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If you switch to T8 or anything else you follow the wiring diagram on the new ballast.
 
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Old 12-22-22, 01:06 PM
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Any 2) tube T-8 ballast will work with your wiring.
You have the socket wiring in place to connect any available ballast. LED tubes too

I have an entire case of these...... Philips ballasts
 
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Old 12-27-22, 08:53 AM
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So to clarify, if converting to LED T8 tubes, no ballast is needed, the ballast just needs to be bypassed. Wiring for this is the Hot connects to only one of the pins on one end and Neutral to the other end. One pin on each side is not connected, correct?
 
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Old 12-27-22, 08:59 AM
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if converting to LED T8 tubes, no ballast is needed,
That depends on the type of LED you buy. Some them still require the ballast. I would be sure to get the ones that do NOT require the ballast.
 
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Old 12-27-22, 12:50 PM
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Some of the replacements require 120v at one end on both pins.
Some want 120v on one pin on each end.
They will come with a diagram.
 
 

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