Converting Old Style T12 Fluorescent Fixture to New Style T8 Ballast

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Old 12-09-15, 11:09 AM
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Converting Old Style T12 Fluorescent Fixture to New Style T8 Ballast

Hello,

I have an old T12 single 48" tube fluorescent fixture with a bad ballast (magnetic I believe). I have a whole bunch of these in my house actually, and have replaced a ballast in kind in one of the others before they were discontinued some years ago. So now, I am trying to adapt the new ballasts readily available to work with this 25 year old fixture, as I do not want to replace this fixture or any of the others since they generally work fine. The old ballast is 120V 60Hz 40 Watts.

I have picked up new two tube ballast Philips Advance Ambi-Star RELB-2S40-N, which has the same specs as the old one above, but for two tubes rather than one, and electronic rather than magnetic. There are significant other differences between them physically though. The new ballast is about 2.5 times longer and thinner, so I'll have to secure it to the fixture differently than the old one, but that is no problem with a drill and some screws and washers.

The wiring, on the other hand, I have some concern about. The old ballast has black and white wires with a silver core (presumably aluminum) with the plastic ends with pin sockets all pre-connected to the red and blue pairs of wires from the ballast. The new one has larger gauge (thinner) wires, but all copper, with all ends pre-stripped for the connections. There are black and white wires for the power source, and three pairs of blue, red, and yellow for connecting to the fixture ends. The pair of blue is supposed to go to the pin socket at one end of one tube, the pair of reds to the pin socket at the end of the second tube and the yellow pair is supposed to be shared at the pin sockets at the other end of both tubes.

I will have to use the old plastic fixture ends with the pin sockets by splicing the wires from the new ballast to the wires from the fixture ends using twist connectors as follows:

pair of yellow wires from the new ballast - to the pair of blue wires on one end connector

pair of red wires from the new ballast - to the pair of red wires on the other end connector

pair of blue wires from the ballast will not be used, as I only need to connect one tube.

When reading the instructions there is something in there that confuses me, though. It reads "Instant start ballasts require the lamp sockets to have both pins of the bi-pin socket shorted together. Rapid or programmed start ballasts require rapid start bi-pin sockets to properly operate."

Question - Are the pins sockets of the old T12 fixtures not constructed so that the pins are already shorted inside the socket? It's impossible to see inside the plastic ends, but I would assume that is the case!

Thank you.

quickcurrent
 
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Old 12-09-15, 01:02 PM
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Are the pins sockets of the old T12 fixtures not constructed so that the pins are already shorted inside the socket?
That is correct. You would connect both wires to a single wire from the new T-8. However all ballasts come with a wiring diagram and you should follow that.
The old ballast has black and white wires with a silver core (presumably aluminum)
More likely tinned copper. Look at a cut cross section.

I actually converted a two tube T-12 to LED for only the cost of the bulbs, $38. (The ballast wasn't needed.) That may be close to your cost for new T-8 bulbs and a ballast.
 
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Old 12-10-15, 07:50 AM
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Thanks, ray2047.

I did indeed see a copper core in the old ballast wires with 10X magnification!

I still have several T12 tubes, so I want to continue using those. They last longer than the ballasts, and I doubt any LED will outlast them, the LEDs just cost one hell of a lot more, with negligeable (if any) electrical savings! Such is the price of progress!!!

The manner of wiring I indicated above is following the new ballast's wiring diagram, with the modification that I will not be using the blue pair of wires (which is intended for a second set of sockets and tube that my fixture does not have). The yellow pair is shared for both pairs of sockets and tubes at the same end of the fixture, again I only need that pair to go to one end of the fixture for a single tube.

I was fairly sure that the wires were connected together inside the socket at each end of the fixture, but just wanted a second opinion. Thanks for that.

I wanted to make sure because I've read online that somebody tried to do something similar only to find that the new ballast was burning out the tubes quickly. But, I suppose that was an issue of mismatched electrical specs.

Thanks again.
 
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Old 12-10-15, 09:44 AM
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I still have several T12 tubes, so I want to continue using those. They last longer than the ballasts, and I doubt any LED will outlast them, the LEDs just cost one hell of a lot more, with negligeable (if any) electrical savings! Such is the price of progress!!!
I doubt you'll get 30-40 years out of a fl. tube...but then how do we KNOW an LED will really last that long?
Prices are falling fast for all types of LED lighting. Best I've seen lately in stores is a 48" direct-replacement LED tube for $9.99 (Home Depot)--but that specific one was for popping into an existing T8 fixture, with ballast left intact. I wouldn't think the ballast makes any difference in the cost to produce the LED stick so I'm confident that T12 direct-wired (no ballast) sticks will soon be $10, too.

Prices are great online but personally I don't trust they would ship undamaged. If ordering a large quantity maybe they would be packaged better. Safety in numbers!
 
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Old 12-10-15, 10:48 AM
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I don't trust they would ship undamaged.
The tubes are plastic so slightly less chance of damage. The ones I bought were poorly packaged but survived shipment with out a problem.
LED tube for $9.99 (Home Depot)--but that specific one was for popping into an existing T8 fixture
It would be interesting to buy one and test it on 120 volts. Since there is nothing about an LED that requires a ballast and most which work with a ballast also work without a ballast I suspect it would work. At that price I may just buy one to test.
 
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Old 12-11-15, 07:09 AM
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Interesting reading, here is my 2 cents.

In Canada prices on most things electrical, mechanical and others tend to be twice what you can get things for in the USA. If ordering from the USA online, most vendors will not ship outside the contiguous states without extra charge, if they ship at all. If shipping to Canada, they will charge exorbitant international rates. Then, in spite of NAFTA, Canadian Border Services will require customs clearing on anything over $19.99, so add $30 for agent's fees, plus import tarrifs and federal and provincial sales taxes. Ouch. Add to that the fact that the Canuck petroleum buck is down to just over 70 cents US, and you can see where I am going - prohibitive.

I have had these fluorescent fixtures with single tubes in the California Lighting all around my kitchen ceiling and one in the pantry since 1988. In that time I have replaced one fluorescent tube and this is the second ballast I've had to replace, out of a total of 11 fixtures. Try to beat that with any other lighting, at any price !!!
 
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Old 12-11-15, 09:22 AM
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I totally understand. My workshop was lit by 215W T12 VHO tubes until recently. Bright as the sun and I REALLY didn't want to give them up but eventually the tubes got to be as expensive as a replacement fixture.

Only you can decide when the cost for maintenance & energy usage exceeds replacement cost & effort.
 
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