Series Connecting T8 Fluorescent Lamps

Yes, that can do. Actually my first priority was to find a 10 lamp ballast. Is it really something uncommon or nobody makes them?

Yes to the first question, and probably Yes to the second. These are electronic ballasts, so you won't have to replace bulbs in pairs, as you do when using magnetic ballasts.

On the other hand, when using electronic ballasts it is ABSOLUTELY ESSENTIAL that you provide a good ground for both the metal shell of the light fixture and the ballast. Failure to do so can result in erratic operation and premature failure of both ballast and bulbs.

You can get the job done by hiring a licensed electrician. This way if your place burns down due to an electrical fault the insurance will cover it.

Thanks a lot for your suggestion. I can always get any jobs done with a licensed (everything)cians that way there wouldn't be any necessity of such forums. But something is true that a license never ensures safety. What ensures safety is our commonsense. I have seen a lot of licensed professional messing up their jobs and a lot of non-licensed people doing sleek jobs. Only difference is those professionals are backed up by insurance. Of course we do call licensed people for something where it is strictly required by law, but I can't believe installing a fluorescent lamp is something like that. And also, electricity is not ghost. It makes it's way very neatly and in a logical manner. So it is really tough to burn your house down with electricity unless you are that kind of nerd. Thanks again.

The ballast set the voltage potential across the lamp. Increasing the wattage will not increase this potential. Placing two lamps in series you may not get them to light up.

They make fixtures UL listed which can be all wired to the same circuit instead of rigging something up and possibly creating a fire hazard. Your life is worth more then few bucks you will save.

Thanks. I thought the voltage across one 8' lamp should be equivalent to that across two 4' lamps connected in series (assuming they are of the same diameter).

After reading your post #12 then this post ... gives me pause. I suggest if and when you do this project , that you read the data sheet of the BALLAST 3 times.

Sure I will read it 3 times :) I never had any hand on experience with electronic ballasts, but I have worked with different types of SMPS and I imagined they most probably work in a very similar fasion. The idea of series connection came from what I saw in some mini emergency lamps where 2 small fluorescent lamps are connected in series across the high tension terminal of to output transformer and they work together, and die together.

Perhaps 10) 26 watt CFLs in recessed housings? Each bulb has its own ballast, so there is never an issue in the future of having to find the right replacement ballast when it fails.

Any reason for not using the standard twin tube fixtures with the standard pre-installed ballasts?

Thats what I was upto. Either 10 x 26w or may be 10 x 32w whichever is more cost and energy efficient. I was interested in a single ballast driving all those lamps in order to keep the wire clutter simple. Using 10 separate ballasts would require a comparatively messy wiring i guess.

The reason for not using standard twin tube fixtures is that -

(1) The width of available space is narrow. Just about 3". Such a fixture won't fit in there.

(2) I don't need the fancy things that come with a standard fixture, like the transparent cover, a beautifully painted metal bar.. etc. since the lamp remains apparenty hidden, just a bare bulb with only necessary accessory is good enough. I couldnt find any reason to pay about $30 for a fancy fixture full of stuffs i dont need.

2 3/4" wide

http://www.grainger.com/Grainger/LITHONIA-Channel-Strip-Fluorescent-Fixtures-3GA61?Pid=search

Thanks. In fact I have seen them at Lowes but 10 or 8 of those would cost me 8 x $26 = $208. So I think I am going with the GE UltraMax 71723 suggested by One2playWitt that will probably get the job done within $50

What do you desire/require in terms of:

1) Saturation (light per area),

2) CRI - Color Rendering Index (look it up),

3) Color Temp (look it up), and

4) Bulb life.

5) From where will the light emanate in relation to the room ... ceiling wall floor?

IE How big is your space ... do you want a single line of 10, or 5 on each side of the room or a 3,3,2,2 in a square room {gives us an idea of saturation} {lumens gives us an idea of how bright you what it}? ... CRI & color temp, tells us how picky you are about the colors you see in the room being correct to their true color. Filming and pictures will look different ... unless you use a aux lighting. Higher color temperature bulbs, make video washed out.

With that said ... let's design this :o) but don't just start slapping things together ... you may not like the outcome.

There are ballast that can handle 300+watts in series (single pin bulb) ... but they are pricey. They require cooling considerations. That would limit you to ten 30 watt bulbs. But, you may only need 15 or 17 watts per bulb and can use a ballast that doesn't have as restrictive a cooling schedule.

Please try to give us as much info as you can ...

More informative question = better answer.

Let me ans by numbers:

1) In lumens I cannot tell exactly but there was 2 x 4-tube fixtures before i.e. 8 x 32w bulbs, which used to illuminate good enough. But since the room is going to be illuminated indirectly (after being reflected to the ceiling) now, I think two more bulbs would produce close to the same output. I didn't go for an exact measurement coz it shouldn't matter much.

2) About CRI I am not so picky, but I'd prefer plain white.

3) Color Temp same as 2)

4) Bulb life - more is better, isn't it ? :)

5) In my original post I mentioned it is ceiling. Room size is 10' x 12' and there is going to be 3 tubes in a row on two opposite sides and 2 tubes in a row on other two opposite sides that forms a rectangle. No space is necessary between tubes so you are free to consider a 8' instead of 2 x 4'. And, no, I am not with photography, so don't worry about those. Thanks.

How & where will the new lights be mounted ...

a typical 60 watt incandescent is about 600 (mean) lumens

a typical 32 watt t8 color temp 5k K is about 2500 lumens ... 8 = 20k lumens or 30 + typical 60 watt incandescents ... in a 10x12 room i'd call that a bit bright.

I'd suggest that 5k lumens indirect would be PLENTY

I just noticed that the room is 10'x12', if that is in feet and not meters, then I am scratching my head as to what you mean by 'indirect lighting' from the ceiling and the type of the previous bulbs you had/have.

4 of the bulbs I listed below, on a single ballast, would be over-kill in my estimation. Perhaps you did not realize the lumen output that a T8 is capable ... when you said you would possibly need 10, I was thinking of a room at least 4 times that size.

Philips

Part No. : 137836

Wattage : 25 Watt <---------

Bulb Shape : T8

Bulb Type : F32T8

Color Temp. (Kelvin) : 4100K

CRI : 85

Life Hours : 36,000

Lumens (Initial) : 2,500 <--------

Lumens (Mean) : 2,425<--------

Warranty : 30 Months

I recommend the following ballast:

Brand : GE UltraMax Family : UltraMax Part No. : 71723 UPC : 043168717236 Voltage : 120 / 277 Ballast Factor : 1.18 Height : 1.2 in. Length : 9.5 in. Width : 1.7 in. Operates : 3-4 Lamps Start Temp. (Min) : -20 F (-30 C) Power Factor : 99% Start Method : Instant Start THD : 10% Type : Electronic Fluorescent Weight : 2.16 lbs. Warranty : 5 Years Case Quantity : 10

Here is a 32 watt bulb that will blow your mind (we use them in hospital hallways) ... at less than $2 a piece in bulk of 25. Sorry, I can't give a price off my sheet for lower quantities. But I'd estimate singles @ $4 US.

Brand : Philips Part No. : 139907 UPC : 50046677139907 Wattage : 32 Watt Base Type : Medium Bi-Pin Bulb Shape : T8 Bulb Type : F32T8 Color Temp. (Kelvin) : 5000K CRI : 82 Diameter : 1 in. Life Hours : 36,000 Lumens (Initial) : 3,100 Lumens (Mean) : 3,025 Warranty : 36 Months Case Quantity : 25 Order Code : F32T8/ADV850/ALTO

With 4 of these in a 10x12 room you might need to wear your sunglasses. When is the last time you lit 20, 60 watt light bulbs in that room.

So if that seems too bright, I cannot reduce the number of bulbs less than 8 (instead of previous plan of 10) because I'd have to have enough bulbs to cover the whole square. May be I can consider T8 25w bulbs instead of 32w for further reduction of lumens, right ? In the meantime, I looked up GE Ultramax 71723 data sheet. That looks like perfect choice for me, since each ballast drives 4 tubes, I can use 2 ballasts for my 8 bulbs for around $50. Well, it did say that maximum remote mounting distance is 18' but I could not find any recommended voltage rating for wires in case I have to extend the wiring (of course within that 18' limit). I know that part would carry a high frequency high voltage, but do you think a 600v grade wire would be enough for any possible extension or you recommend even higher voltage ?

I'd even suggest that you could use 4 total 25 watt bulbs ... or move down to 17 or 18 watts ... again I do not know your means of 'indirect' lighting. Yet below 25 watts, T8's become less efficient. As I remember, an 18 watt T8 will put out less than half what a 25 watt will typically (don't quote me on that ... my experience is with 25, 32 and 59 watts). Now that you know the lumen situation, you can be the judge of that.

Were you surprised at the 25-32 T8 bulbs' lumen output? ;o)

My last suggestion would be to go with a color temp in the 4000's for indirect ... if you want a softer feel. Low 5000 range is better for crisp definition ... but generally not as good for indirect lighting (unless you like a more 'commercial' feel). 6000 Color temp is weak in the red end of the spectrum, making reds and oranges appear too similar ... creating a "washed out" look. Below 4000 everything looks orange or like your sitting in front of a fire.

BTW the 18' is how far you can run the wires from the ballast, not how far you can run the wire from the switch. I'd be willing to bet you didn't read it three times :o(. 300V wire ... 277 is the max so 300 is fine for that ballast BUT DON'T DO THAT !!! Mount the Ballast closer to the bulb ... in the attic if possible ... all ballasts hum a little (the recommended one perhaps less than most others) & get hot. So it is advantageous to mount it in the attic area if possible.

Let me know how it turns out ... post a picture if you can ... :o) ... out!

Ok. Let me try to add some more explanation. I searched on the internet and found this picture that looks similar to what I am trying to do.

Since the area of the square is predefined, I cannot just omit one or two bulbs from somewhere, because that would make that area look darker. I didn't know that I can add picture here before you mentioned. Since light is not getting down to the floor directly, it's getting reflected from the ceiling and then part of it is comming down, so I called it indirect. The two 4-bulb fixtures were installed suspended from the center of the top ceiling before which I took off already.

And of course I understood that 18' distance is from ballast, not from switch. There is no reason to mix them up. Yes, I did read it only once, coz I was to read it 3 times before I start to work :)

"Mount the ballast closer to the bulb" - from the picture you can guess that the ballast has a little chance to stay very close to the furthest bulb, because bulbs are not sitting parallel to each other. Each of the bulbs is adding 4 more feet distance from the ballast and that's where the concern of 18' limit comes from. Each ballast drives 4 bulbs, so the best possible scenario is if I put the ballast in the middle position then the furthest point would be 4 x 2 = 8' from the ballast which must be wire connected.

So are you saying I can safely use 300v grade wire there ? I thought high frequency carriers have a capacitive effect because of what a little electricity leaks through wire insulator when two wires lies side by side, and the amount of flow increases with the length of the wires. Thats why insulators with higher voltage rating is used for higher frequency lines. And also, that's what limits the length of such pairs of wires. Please correct me if I am wrong.

'I thought high frequency carriers have a capacitive effect because of what a little electricity leaks through wire insulator when two wires lies side by side, and the amount of flow increases with the length of the wires. Thats why insulators with higher voltage rating is used for higher frequency lines. And also, that's what limits the length of such pairs of wires. Please correct me if I am wrong.'

Good question ... and it made me a little ill thinking I never took that into consideration ... so I called GE a few moments ago to confirm my previously used methodology ... which was to exceed the 3 phase voltage and not exceed the remote length with 18AWG.

He jokingly said '18 gauge ... 300v ... do not exceed 18 feet ... final answer' ... like he was playing who wants to be a millionaire. He took another minute to say ... because it is an electric ballast not a magnetic ballast. Square wave versus sine wave. Then I said AH! ... glad I never used that method with magnetic ballast ... He said, yeah ... mee too.

Looks like you are with 300v. May be its going little bit off topic but I couldn't but say that we are probably missing a point. A lot of companies have people even in technical service dept to answer phone calls who are not really with technical stuffs but are able to answer our questions going through the script. I doubt if the GE guy was anything but a customer service rep, due to the fact that a square wave is much more susceptible to high frequencies than a sine wave. You know, although the standard square wave form theoritically looks like this picture below:

but in practical square wave generators produce waveforms like the one below, its from a oscilloscope display:

Look at the high voltage spikes at the begining of each half-cycle. I believe anyone with electricity are familier with those killer spikes. For example, with a 50v peak those momentary spikes can hit as much as thousand volts, which are essentially present in all kinds of simulated AC power drivers involving square waves. Sine waves are normally free from it and therefore much easier on equipments.

Well, as an example, may be I can mention of Keystone Technology's CAT. 140TPWS which are now obsolate (replaced by KTEB-140-1-TP-EMI-WS) but I have some of those in hand. They are FC12T9/FC16T9. I just double checked those ballasts to make sure it supports what I am saying, and I found the wires used to connect the tubes are 1000v 18AWG. Obviously it does make sense, a thousand volts rating wire has not been used there for no reason. What do you think ?

I deferred to my company's EE who said ... the new electronic ballast are specially made (rectifier and capacitor) to remove high frequency components from the square wave; in other words the corners are not exactly square but rounded.

Additionally, the power factor was high and some other stuff I couldn't quite grasp .. but in the end said ... the ballast in the last 3 years are essentially idiot proof ... that is why it says use 18 AWG with no mention of voltage requirements and you won't have a problem.

We had a great time getting the light pools wired up in our new home - the first electrician didn't know how so we had the company we bought the lamps from send a guy. The system is T5 lamps with dimmable electronic ballasts.

Ended up working fine though.

'dimmable' would be a great thing !

Have you priced the dim-able switch that you also need with the dim-able ballast? ;o)

the switch alone is 70-110 bucks :o)

go to GE site or look up light designing program ... use a coeficient of use as .3 to .5 (indirect lighting) and you see the set up I recommended puts you at 30 candle-feet which is what OSHA recommends for a working enviroment.

http://www.gelighting.com/na/business_lighting/education_resources/tools_software/toolkit/layout.htm

Also the ballast I initially recommended was a high output ballast ... look through the site ... you may be better off with an n+ of n instead of the H, that I initially recommended.

http://www.gelighting.com/na/business_lighting/education_resources/literature_library/ballast/downloads/UltraMaxInstantStartBallasts11x17.pdf

wowwwwwww... in that case I woudnt want dimmable