Getting the Most Out of CFLs

Lately, the lighting technology used in the farming industry has been moving away from incandescents, and towards fluorescents, induction lighting and LED technology. Although many people have jumped at the chance to use these new lighting options, few really understand how to use them properly. Not surprisingly, one of the most common questions I get on poultry farms is “What do you think about those dimmable fluorescents?” followed by “Will they really save me money?” and “Will I have to change anything?”

The compact fluorescent lightbulb (CFL) is gaining a lot of popularity because of the energy savings it can offer. When you are running several hundred feet of lighting rows for the bulk of the day, it catches the interest of farmers. They take only a fraction (generally half to one-fifth) of the wattage (billable power from the power supply company) to run, and have advertised lifetimes of up to eight years. This makes them seem like a very smart investment right off the shelf, but there are a few things to take into consideration before you purchase lights and change over your barns.

First, the CFL is a band-aid fix for the inefficiency of the incandescent bulb. The lampholders  present in all houses and barns dictate that any lighting replacement used must be of a similar size and shape, and work off the same voltage characteristics. And since numerous locations (including British Columbia) will soon  be banning the manufacture of incandescents, there had to be an energy-saving alternative. Where an incandescent bulb only takes about 10 per cent of the power to create light and the rest is wasted as heat, a CFL uses close to 90 per cent of its power to create light and dissipates the rest as heat. This heat that the bulbs create is insufficient to heat your barns in the winter, but during the summer heatwaves, anything that can be done to lower the barn temperature is critical.

When you first look at a bulb, take a closer look at the advertised lifetime. The most common advertised lifespan is four years. But if you read the fine print on the packaging, most companies state that the bulb is good for four years of operation, for four hours a day. This means that if you want to have 16 hours of operation a day, you will be getting only a year of rated life out of it. In actuality, you will probably be getting less life than that even, as the longer burn time will eat away at the cathode inside the bulb. Base your lifespan and “power savings versus bulb cost” calculation on the actual calculated burn time rather than the rated lifespan.

Light output is going to be the same with a smaller wattage CFL versus a regular incandescent, but the light value can  often be compromised by the barn environment. With a standard incandescent bulb, the glass “bulb” holds onto a lot less dust and debris than the standard glass “swirl” tubing of a CFL. If possible, try to buy CFLs with clear shrouds over the tubing, as barn dust can obscure up to 40 per cent of visible light from being transmitted out to the work area.  With a proper, regular blowdown of the barn, most of that can be eliminated, but a CFL with a “bulb” over top of it will hold far less dust, and stay brighter longer.

If you are only controlling your lights through a switch or contactor, most types of CFLs will work. However, if you are planning a dawn-to-dusk or dimming lighting cycle, then you must buy dimmable bulbs. You cannot dim CFLs unless you have bought bulbs that are designed to be dimmed and sold as “dimmable.” Otherwise, although you may get a few startups out of the light, it will not last, nor will it properly dim.

Along with buying proper bulbs to be able to dim, your actual dimmers used on the circuit must be compatible with CFLs. Most barns using rotary dimmers have large, commercial grade dimmers in the range of 1,000 to 2,000 watts. Although that size of dimmer is necessary when using incandescents, it will not have a large enough load on it to operate properly when using CFLs. As well, any programmable electronic, digital, or remote-control dimmers will not work well with the lamps, and may cause strobing, flickering or bulb failure. Any non-compatible dimmers used on the circuit should be taken out and replaced with an analogue dimmer no larger than 600 watts, and manufactured after 1995.

A CFL will not dim down past 20 per cent, but should offer fairly smooth dimming throughout the rest of the cycle. However, if operated at below 50 per cent light output for extended periods of time, the heating filament that pre-warms the gases in the bulb will have a significantly shorter lifespan (below rated output) than if it operates at 50 to 100 per cent light output. Therefore, it is very important to pick a bulb with a light output closer to what is desired, rather than dimming it down too far in search of the desired lighting level. A standard 15- to 20-minute dawn/dusk dimming period is fine on most bulbs, but at catch time the minimum dimming level of 20 per cent can still be too bright, meaning rows of lights might have to be shut off or bulbs unscrewed.

Lastly, upon the initial installation of the circuit, the bulbs should be left on for at least 100 hours consecutively for what is called the “burn-in” period. Most lamp manufacturers recommend it, as it increases the overall lifespan of the bulb. Often farmers are not told about this and, therefore, never do it, which often leads to premature failure of the bulbs.

Compact fluorescent lightbulbs, if bought for a low enough price or subject to power savings rebates, and installed properly, will save you money. However, they are less robust, will be more expensive initially, and may require changing of equipment to work properly. The best place to use them is on barns without dimming, as the dimming can cause problems if done improperly. In the next five years, the LED (light-emitting-diode) technology should become more prevalent and cheaper, as it is a smoother, more accurate, and more efficient dimming type of light. Until then, however, as far as saving energy and reducing heat goes, CFLs are a viable alternative to the incandescent.

Joel Feenstra is the owner of Feenstra Electric in British Columbia’s Fraser Valley. He specializes in poultry and dairy farms, automation, mills, and processing plants, and is a part-time electrical instructor at the University of the Fraser Valley. If you have any other questions, he can be contacted at feenstraelectric@gmail.com or by phone at 778-344-4686.