DIY Home Improvement Forum banner

1 - 12 of 12 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1
summary: Grounded shoplight fixture mounted in apartment kitchen, had 2xF40T12 bulbs and noisy T12 ballast, replaced with rapid-start electronic T12. Good light for ~6 weeks, then severe dimming. Replaced bulbs with known-good pair of same kind F40T12. Good light for 2 weeks, then dark. Switch looks good to voltmeter. Is ballast bad, or should I be using different bulbs, or something completely different?

details:

I rent an apartment, the kitchen of which has a grounded, built-in, shoplight-style lamp, originally with el-cheapo Philips Alto F40T12/CWX bulbs and an old, noisy, magnetic ballast. I asked for and got the ballast replaced: maintenance put in a Philips Advance Ambistar rapid-start electronic T12 ballast (part# RELB-2S40-N). (I asked for T8, but apparently the complex is not ready to switch from T12.) They also kept the same bulbs. That worked great (quiet, good light) for ~6 weeks. Next day I turned it on (via wall switch), and light was less than half brightness. I replaced both kitchen bulbs with known-good F40T12s (also both Philips Alto F40T12/CWX) from another fixture with a magnetic ballast, which solved that problem ... for about 2 more weeks, when the same thing happened: turn on kitchen switch, get dim light.

Just to be sure, I checked the switch with a voltmeter, but I'm getting reasonable VAC values between ground screw and black and white inputs to ballast (and across the inputs). I also noted that the label on the ballast explicitly says it's compatible with F40T12 bulbs (either 1 or 2 in lamp), as well as F34T12 and F30T12.

So ISTM the ballast is bad--"infant mortality." Am I missing something? Particularly, should I be using another type of bulb with the rapid-start ballast?
 

·
Electrical Contractor
Joined
·
1,145 Posts
did you check the wiring diagram on the NEW ballast to see if the fixture is wired correctly, ?? sometimes you need to rewire it ..
 

·
Registered
Joined
·
4 Posts
Discussion Starter #3
debugging

worked great (quiet, good light) for ~6 weeks.
did you check the wiring diagram on the NEW ballast to see if the fixture is wired correctly, ??
2 responses:

First: could it have worked properly for 6 weeks if it had been wired incorrectly? Seems improbable: am I missing something? (FWIW, though I am not an electrician, I did instrumentation electronics for years, and am using a decent Fluke multimeter.)

That being said, looking at the fixture with the cover off, the ballast wiring does matches what's printed on the ballast label. Also,

I'm getting reasonable VAC values between ground screw and black and white inputs to ballast (and across the inputs).
namely, with all values in volts AC:

  1. across black and white: switch off=4.1, switch on=120.2
  2. black to ground: switch off=4.2, switch on=103.6
  3. white to ground: switch off=0.2, switch on=2.0
 

·
Licensed Electrician
Joined
·
4,352 Posts
With the older magnetic ballasts, you could burn out a ballast very quickly if you didn't install new lamps as well. I haven't had that trouble with the electronic ballasts, but I always change the lamps when installing a new ballast.

Did you install new lamps when you changed the ballast out?
 

·
Electrical Contractor
Joined
·
1,145 Posts
summary: Grounded shoplight fixture mounted in apartment kitchen, had 2xF40T12 bulbs and noisy T12 ballast, replaced with rapid-start electronic T12. Good light for ~6 weeks, then severe dimming. Replaced bulbs with known-good pair of same kind F40T12. Good light for 2 weeks, then dark. Switch looks good to voltmeter. Is ballast bad, or should I be using different bulbs, or something completely different?

details:

I rent an apartment, the kitchen of which has a grounded, built-in, shoplight-style lamp, originally with el-cheapo Philips Alto F40T12/CWX bulbs and an old, noisy, magnetic ballast. I asked for and got the ballast replaced: maintenance put in a Philips Advance Ambistar rapid-start electronic T12 ballast (part# RELB-2S40-N). (I asked for T8, but apparently the complex is not ready to switch from T12.) They also kept the same bulbs. That worked great (quiet, good light) for ~6 weeks. Next day I turned it on (via wall switch), and light was less than half brightness. I replaced both kitchen bulbs with known-good F40T12s (also both Philips Alto F40T12/CWX) from another fixture with a magnetic ballast, which solved that problem ... for about 2 more weeks, when the same thing happened: turn on kitchen switch, get dim light.

Just to be sure, I checked the switch with a voltmeter, but I'm getting reasonable VAC values between ground screw and black and white inputs to ballast (and across the inputs). I also noted that the label on the ballast explicitly says it's compatible with F40T12 bulbs (either 1 or 2 in lamp), as well as F34T12 and F30T12.

So ISTM the ballast is bad--"infant mortality." Am I missing something? Particularly, should I be using another type of bulb with the rapid-start ballast?
that is for a ONE BULB setup ...

http://www.capitalelectricalsupply....=3622&cvsfe=2&cvsfhu=42412d52454c42325334304e
 

·
Registered
Joined
·
4 Posts
Discussion Starter #7
bulb/ballast compatibility

[maintenance] replaced [ballast] with rapid-start electronic T12. Good light for ~6 weeks, then severe dimming. Replaced bulbs with known-good pair of same kind F40T12. Good light for 2 weeks, then dark.
I suspect the maintenance man not changing the lamps upon ballast replacement is the issue here.
You're correct that in neither case were the bulbs new. Maintenance took the old bulbs out, replaced the ballast, put the old bulbs back in. I then took those bulbs out and substituted bulbs from another working lumiere.

I'll try a pair of new F40T12s. Or would something else be more compatible with a rapid-start electronic T12 ballast? I'm wondering because

  1. I've heard (and seen in this forum) that T12 bulbs are not compatible with T8 ballasts and vice versa. Granted, in this case, it's T12 bulbs with a T12 ballast, but ...
  2. I'm a bit confused by the concept of "rapid-start electronic T12 ballast." As basically Just Another Member Of The General Public, I know that the number following the 'T' refers to diameter in eighths-of-an-inch. But I also thought T12 implied magnetic ballast and T8 implied electronic ballast, and furthermore (see item#1) that they were in some sense incompatible.

So I guess my secondary question (primary being, "how do I get light in the @#$%^&! kitchen again?" :) is:

Are "normal," el-cheapo T12 bulbs (of the kind my super is probably buying for $1 each) really compatible with these electronic T12 ballasts? Or are, "from the bulb's point of view," electronic and magnetic T12 ballasts electrically equivalent?

Obviously that's an empirical question, so I defer to folks who do this sort of thing frequently. Please shed some (fluorescent) light on this subject (pun intended :)
 

·
Licensed Electrician
Joined
·
4,352 Posts
Bad lamps can make ballasts go bad. I had a brand new ballast go bad in less than 2 weeks with bad lamps.
 

·
Registered
Joined
·
9,298 Posts
But I also thought T12 implied magnetic ballast and T8 implied electronic ballast, and furthermore (see item#1) that they were in some sense incompatible.
Originally T12 meant magnetic ballast. The electronic ballast was actually developed on the T12. But the T12 bulb uses "slower" response phosphors because the bulb was developed around the 60 cycle speed of the magnetic ballast.
With the electronic ballasts, you are not limited to 60 cycle speed. But due to the T12 bulb, there is an upper limit to how fast you can push it.

So the T8 bulbs were created, using "faster" phosphors. T8 ballasts operate at higher cycle rates than the T12s. The T8 system produces more lumens per watt than the T12. A 32 watt T8 produces about the same amount of light as the comparable 40W T12.

So, a T8 is always electronic. T12 can be either, although only electronics are now sold as replacement ballasts. And yes consider the bulbs as not being interchangeable. Neither bulb will give you full performance on the wrong ballast. Shortened bulb life is guaranteed. Ballast failure is possible, and some will say likely.

Most T12 bulbs are being phased out. They have not been made in the US or imported since July 2012.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #11
solved for now

Thanks, all. IIUC the problem could be either the ballast or the bulbs, but the ballast could be making the bulbs go bad, and anyway one should replace bulbs whenever one replaces ballast. I noticed I could get a cheap 48" double-sided LED for not much more than the (retail) cost of a ballast and a pair of bulbs, so I said "@#$% it" and just wired around the ballast. (I'll wire it back when I "check out.") The one LED is probably not quite as bright as the pair of fluorescents, but it's close enough, and is *really* quiet, which is what got me into this.
 

·
Registered
Joined
·
1,602 Posts
I have been having so much trouble with the T12 with electronic ballast that I finally decided to remove the tubular fixture completely and rewire for two standard edison sockets, and now use CFL's. Of course, I could do this because it is my house, not an apartment, but I'm just making the point that the T12 bulbs and electronic ballasts being sold today are junk.
Note also that one of the fixtures I was having all this trouble was a Diamond Plate, which I had thought was a superior brand.

I think you did the right thing to go with the LED bulbs. That would be my next option, but I am waiting for those to come down in cost to be more on the line with CFL's.
What I like about the CFL's is that when you replace a bulb, you are replacing bulb and electronic ballast. No issues with bad bulb/good ballast or visa/versa.

FW
 
1 - 12 of 12 Posts
Top