Ballast Questions

What ballasts do you use in your assembled fixtures?

When searching for products Richard found several ballasts from the Asian market that provide the performance necessary for film/video lighting without the cost normally associated. The problem has been that there are large stage and studio lighting manufacturers that have propagated some myths that they have some components or some other technology available that is not available to anyone else. And you will hear statements like “Ballasts from China are cheap and unusable for our purposes.” This is simply not true! Maybe it was true at one time (at the dawn of the fluorescent film/video lighting era perhaps) but not today. The reality is that most all ballasts today are made in China. Fulham, Osram, Philips, Advance, Universal—most of their models are all manufactured there. While you can certainly find very cheap ballasts that wouldn’t be very suitable for a fluorescent video light, you CAN find many reasonably priced models that DO offer the results you would expect. Richard tested no less than 20 models while in China and found the cream-of-the-crop to offer in his reasonably-priced, fully-assembled fixtures.

What are the specifications of your ballasts?

Lamp Type: PL-55w
Number of Lamps Driven: 1 or 2 (all Cool Lights Softlight Series fixtures drive 2 lamps per ballast)
Voltage: Universal (100v – 277v) 50/60hz
Output Frequency: 40khz
Input Watts: 105w for 2 x 55 biax lamps
Power Factor: .>.95
THD: < 15%
Protection against open circuit and lamp fault conditions
Class P, Type 1 Outdoor

I’ve heard that some ballasts flicker or hum—why is that?

The older magnetic ballasts had some problems with this. They drove fluorescent tubes at a 50 or 60 hertz rate (50 or 60 times per second—depending upon the type of voltage used in your country). New electronic ballasts have virtually eliminated these problems. Only the cheapest, most poorly designed (mostly for household use) electronic ballasts (with low refresh output rates) will have these kinds of problems. Cool Lights ballasts were all chosen because of their quiet, flicker-free operation. The frequency our ballasts drive the bulbs is 40 khz (40,000 hertz). This is why there is no flicker problem. You’ll get years of great service for use in film and video lighting out of our ballast-equipped fixtures.

Do you offer a dimmable version of your fixtures?

Yes we do and at a price point unheard of for dimmable fluorescent.  We offer a “manual dimmable” model in both our studio and portable fluorescent fixtures.  This means there is a dimming dial on the fixture that allows continuous dimming from about 5% to 100% intensity.  These models are a bit higher in price than our economical non-dimmable but that’s because of the special dimmable ballasts required to make them possible.  Future versions will include a remote dimmable studio model that will allow DMX or traditional dimmer packs to remotely dim the fixture through line voltage or other methods.  Stay tuned for those developments.

I understand that some film/video fluorescent fixtures use ballasts that overdrive the tubes for more lumens—do you do this?

Even many of the best electronic ballasts will output around 85 to 90 watts to drive two 55 watt tubes. So you say “but it should be 110 watts right? Why do they do this?” The answer is simple. They do this to save tube life! Remember, most of these ballasts will end up in fixtures in warehouses and grocery stores (not on film sets) so they consider the consumer who will favor tube life in these settings. In film and video, we don’t always care so much and are simply looking for light output. Richard had the choice of choosing bulb life or lumens and chose lumens. So all Cool Lights ballasts output maximum watts possible for a 2 x 55 watt ballast or about 105 watts to drive two 55 watt tubes. But then you ask “but again 2 x 55 =110 watts so why aren’t you outputting 110 watts?” Another simple answer: the specification that you always see on ballasts called “power factor” indicates what percentage of the ballasts rated wattage it can actually achieve in real use. So if the power factor is .95 (very common) then the output from a 110 watt ballast (at its maximum) would be about 105 watts. Then you ask: “Are there ways to actually drive the tubes at 110 watts?“ Yes! We could have chosen to drive them even harder by selecting a higher power ballast (and we may do so in the future as an option) or by taking a 2×55 ballast and wiring both outputs to one tube, but we feel the current method we use is adequate for most people’s needs and still manages to balance tube life with lumen output.

Is there any Ballast Wiring Support available for a DIYer?

We provide information where we can but ultimately you must be on your own in a DIY effort; and thus should have the skills to understand wiring diagrams and what they really mean as well as the ability to debug any eventual issues.

What are the best ballasts for 55w biax tube DIY projects?

The 55w ballasts are in the class of “T5HO” and there are many good ones that can work for a 55w project. You’ll want the ones that specifically state they work with either F54 54w T5 tubes or FT55 tubes which are the classic biax like Cool Lights uses. Of course you can get both dimming and non-dimming versions with the dimming ones being the most expensive by a large margin. You always want to get the 2×55 versions that drive two tubes as the cost ratio is better on them than the ones that drive one tube alone. Here are some good ones that work well separated into dimming and non-dimming versions:

Advance Centium ICN-2S54 Intellivolt model which works from 100 to 277v so it can work anywhere in the world.
Universal B254PUNV-D also universal input voltage.
Sylvania Quicktronic QTP2X54T5HO/UNV PSN (universal input voltage–we carry this one in stock)
Fulham Workhorse 5 (110v or 220v models)

In dimming we have two categories: the 0 to 10v which require a control voltage from a special dimmer to operate them or the Inductance type which you can actually use an inductance dimmer or motor speed controller on the line voltage 110v or 220v going into the ballast like you can with a tungsten light–as you do so, you get dimming on the fluorescent lights being driven by the ballast. Very cool stuff, but rare to find and very expensive. The 0 to 10v are still very expensive but less rare and available from more sources.

Dimming (0 to 10v models)
Advance Mark 7 RZT-2S54 120v (or 277v for other countries than USA)
Sylvania Quicktronic QT2x54/120 PHO-DIM (or QT2x54/277 PHO-DIM outside of USA)

Dimming (inductance type)
Advance Mark 10 REZ-2S54 120v (inductance dimming version) (or get the 277v for elsewhere outside of USA)

Phillips and Osram make some nice dimming ballasts but for the most part, these are only available in other parts of the world besides the USA.

Also, always double check to make sure you’ve got the model that works in the USA or whatever country some others may be in. There are some models in the same line which work with 380 volts and some other odd combinations which are totally unusable for most people.

Where can I get any of those ballasts you mentioned?

Typically, they can be found at a professional lighting supply in your city or often can find them online too. I occasionally caught some of the Advance non-dimming ones on Ebay for around $15 to $17 each with shipping and that’s a very good price. Ebay is the most likely source to find some ballasts on clearance or surplus type deals. Otherwise, if you pay anywhere near retail, you’ll be paying around $50 for non-dimming ones and $160 for dimming ones.

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