Fluorescent tubes and fixtures.

[terry]

Have just been given some fluorescent light fixtures from a school.

Each four tube fixture has a single 'electronic' ballast. The fixtures use the skinnier/newer type tubes. I also received some of the newer type tubes about one inch diameter.

All fluorescent tubes referred to here are the 48 inch style. (Yes I ran into a few 'metric' ones a few years ago, which are a couple of inches shorter)!

I also have older type fixtures. These have non-electronic ballasts and two tubes per fixture. Also a generous supply of the older style 40 and 34 watt fluorescent tubes and spare new and used (non electronic ballasts).

I put a two of the the newer tubes into an old style fixture just to test them out and they worked but after a while the non-electronic ballast appeared to overheat and then operated intermittently (probably due to thermal protection inside it cutting in and out?).

Q1: So it appears that it is NOT possible/safe/advisable to use the 'newer' tubes in 'older' fixtures?

I also put four of the older style tubes into one of the newer (electronic ballast equipped) fixtures and they worked, fine it seemed.

Q2: So is it OK/possible/safe to use the older style tubes in an electronic ballast equipped fixture?

Mechanically everything fits fine. Advice appreciated. Terry

[JohnR66]

The "older" ones are probably T12 and the newer ones are T8. They have differing voltage and current characteristics and are not interchangeable. John

[Bennett Price]

[terry]

No they are all 120 V AC 60hz etc. No doubt whatever. In fact the fixtures I obtained seem to have been retrofitted with new (electronic) ballasts/tubes and some new wiring during the last say ten years? See last para. . Now you've mentioned it I do have some 8 foot 347 volt fixtures. From a supermarket that must have had 3 phase system? And to buy replaceent

120 volt ballasts for them would be expensive.

Until I got these newer 117 volt ones with electronic ballasts, discussed above, I was going to feed the eight footers with a 115 to

230 (step up; voltage aiding) transformer. So that 115 + 230 = 345 volts. The total wattage not counting transformer losses would have been about 4 x 160 = 640 with the transformer (I have a couple suitable) handling about two thirds of that

It could have been wired in a somewhat standard manner with a continuous non switched neutral, a single pole switch in the live 117 volt lead and red labels on everything to warn future 'electricians' of the 345 volts!

It would also be possible to use 230 volts with a step down, but voltage aiding transformer; 230 + 115 = 345 volts. But that most likley would require two pole switching of the the two 230 volt legs to remove all voltage in the 'switch off' state to puzzle future electricians even more! In that case the transformer would handle about one third of the total wattage.

Any way thanks for the information regarding which tubes to use with which ballasts/fixtures. Makes sense.

Some of our schools must have spent large amounts for the installation of the electronic ballasts and new tubes! Whether the justification/rationale was better illumination or reduced electrical consumption???? I know in on case at least they not only installed the newer tubes but also shiny reflector strips behind them.

Thanks.

[Robert Gammon]

Electronic ballasts cut the total power consumption of the fixture by

33%. Lighting costs drop, HVAC costs drop, at least in summer. STRONG economic justification for the change to electronic ballasts when the ballast cost drops to the right price.

[CJT]

... and the bulbs last almost forever.

[RickR]

For you and anyone else with the same problem.

The ballast should state on the lable what kind/number of lamps it can run! Some are very "universal" some are not. If it's so old you can't read the lable, throw it out!

RickR

terry wrote:

[RickR]

For you and anyone else with the same problem.

The ballast should state on the lable what kind/number of lamps it can run! Some are very "universal" some are not. If it's so old you can't read the lable, throw it out!

RickR

terry wrote: