FLUORESCENT BALLAST FAQS

WHAT IS THE TYPICAL LIFE OF A BALLAST?
WHAT IS CREST FACTOR?
DOES AMBIENT TEMPERATURE HAVE AN EFFECT ON THE PERFORMANCE OF A SYSTEM?
WHAT IS EMI/RFI?
WHAT IS LAMP OPERATING FREQUENCY?
DO BALLASTS CAUSE INFRARED INTERFERENCE?
WHY DO SOME BALLASTS MAKE NOISE AND ARE THERE QUIETER OPTIONS?
WHAT IS THE DIFFERENCE BETWEEN A SYSTEM WIRED IN SERIES AND A SYSTEM WIRED IN PARALLEL?
WHAT IS THERMAL PROTECTION?
WHAT ARE TYPE 1 BALLASTS?

WHAT IS THE TYPICAL LIFE OF A BALLAST?
STANDARD fluorescent magnetic and electronic ballasts are intended to operate an average of 50 000 hours (at maximum rated case temperature). The useful life of a fluorescent ballast depends on the daily hours of operation and the operating temperature, the latter being the most critical. It is important to note that increasing the operating temperature by 10°C will cut the life expectancy in half, and lowering it by 10°C, will double ballast life.

WHAT IS CREST FACTOR?
Crest factor is the ratio of the peak current value divided by the RMS current value. High current crest factors will reduce the life of the lamp. Many STANDARD electronic types of ballasts have low crest factors.

DOES AMBIENT TEMPERATURE HAVE AN EFFECT ON THE PERFORMANCE OF A SYSTEM?
The ambient temperature of a normal lighting installation is usually 25°C, which is why fluorescent fixtures are tested at this temperature. Lamps will operate down to 10°C (50°F) for standard lamps and 16°C (60°F) for energy saving lamps.

However, many applications (without air conditioning for example), have ambient temperatures as high as 50°C at the light source. An ambient temperature rise as minimal as 1°C, can cause ballast case temperature to rise by 0.9°C, which will affect lamp light output as most fluorescent lamps optimally perform at an ambient temperature of 25°C.

Low temperatures and cold weather applications such as outdoor or underground parking applications can affect starting and operation. If the ambient temperature decreases further the result will be decreased light levels and increased difficulty in starting the lamps which can lead to early lamp life failure. The ballast must always operate below the maximum rate case temperature in order to maximize life and operation.

WHAT IS EMI/RFI?
Electromagnetic interference (EMI) or radio frequency interference (RFI) are unintentionally generated power that has a potential to interfere with other devices operating at high frequencies, such as radios, televisions or medical equipment. EMI/RFI levels are regulated by the FCC, and are usually reduced by filters, suppressor or other devices.

WHAT IS LAMP OPERATING FREQUENCY?
There are two types of operating frequencies associated with fluorescent ballasts: input and output frequency.

• Input frequency is delivered by the power company (utility). In North America, 60 Hz is the norm.
• Output frequency is sometimes referred to as the lamp operating frequency. This is the frequency that the ballast delivers to the lamp. Magnetic ballasts deliver 50/60 Hz; whereas electronic ballasts deliver a frequency greater than 20 000 Hz. Fluorescent lamps can accept either of these frequencies.

The FCC however, regulates certain ranges such as 30-40 kHz and 56-62 kHz.
STANDARD brand electronic ballasts comply with FCC regulations operating above 20 kHz but avoiding the restricted ranges.

DO BALLASTS CAUSE INFRARED INTERFERENCE?
Infrared energy is emitted by fluorescent lamps, and may interfere with infrared controls. To avoid any interference, either increase the distance of the fluorescent lamp and the infrared equipment or use a protective shield for the infrared receiver to minimize this effect.

WHY DO SOME BALLASTS MAKE NOISE AND ARE THERE QUIETER OPTIONS?
Fluorescent lighting fixtures produce a vibration (a slight buzzing sound) that originates in the core and coil assembly of magnetic ballasts. The buzzing sound can increase based on a variety of factors, including:
• The fashion in which the ballast is mounted in the fixture
• The design of the fluorescent lamp fixture
• Reverberating characteristics of the ceiling, walls, floors and furniture
• Ballast size: generally, the larger the ballast, the more humming it generates

To help sort through the variations, all ballasts carry a published sound rating of A, B, C, or D. These sound ratings are based on measurements of average ambient noise levels during conditions of normal occupancy. The following chart illustrates the average ambient noise level per application, and the corresponding recommended sound rating.

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WHAT IS THE DIFFERENCE BETWEEN A SYSTEM WIRED IN SERIES AND A SYSTEM WIRED IN PARALLEL?
Lighting systems can typically be wired in two types of circuits: series or parallel. In a series circuit, when one lamp fails the circuit is broken and this causes all other lamps in the system to extinguish. Contrary, in a parallel circuit, the lamps actually operate independently of each other so, if one lamp fails, it does not affect the circuit to the other lamps, and they will continue to operate.
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WHAT IS THERMAL PROTECTION?
In accordance with the National Electrical Code (NEC), all canned and potted electronic fluorescent ballasts require built-in Class P Thermal Protection. This protection is provided by a switching device that shuts down the circuit if the ballast temperature rises to 105°C or greater.

The switching device will reset so the ballast will resume operation once the ballast cools down. This off-again, on-again cycling will continue until the cause of the excess heat is eliminated.

WHAT ARE TYPE 1 BALLASTS?
These ballasts are designed to meet cUL requirements for Type 1 use. Type 1 states that if ballasts are to be used in outdoor applications, a metal enclosure is required.