Interior Lighting for Designers

output as it is measured is different from
light perceived by the eye. See page 143.)
For four-pin compact fluorescent lamps (T4
quad-tube, T4 triple-tube, and T5 long twin-
tube), electronic dimming ballasts will dim to
5 percent of measured light output (22 per-
cent of perceived light). New lamps must
first be operated (“seasoned”) for one
hundred hours at full power prior to dimming
to achieve proper dimming performance and
ensure average rated lamp life.

Fluorescent Heater-Cutout Ballasts
Heater-cutoutelectromagnetic ballasts have
an electric circuit that removes the voltage
supplied to the electrode heaters in rapid-
start fluorescent lamps after the lamps are
ignited and operating. Heater-cutout ballasts
consume approximately 20 percent less input
power than do standard electromagnetic
energy-efficient ballasts; lumen output is
reduced by approximately 12 percent.

Other Ballasts
In addition to standard ballasts, several
kinds ofenergy-savingballasts are made.
These fall into two categories: (1) ballasts
that save energy by reducing wattage con-

sumed as well as reducing light output, and

(2) ballasts that, because of refinements in

design, save energy chiefly by reducing watt-

age loss in the ballasts themselves.

Class Pballasts are equipped with auto-

matically resetting thermal protectors. These

turn off the power when the operating tem-

perature exceeds the limits specified by

Underwriters Laboratories (UL) to prevent

overheating. When the ballast cools, the

protector resets, restoring operating power

to the ballast.

The UL symbol applied to luminaires

indicates that Underwriters Laboratories has

examined a sample unit and determined

that it complies with appropriate safety stan-

dards. It indicates that when properly

installed, such a luminaire will operate

safely. The UL label is also applied to compo-

nents, such as transformers and ballasts, to

signify that the components meet safety

requirements. (The UL label indicates overall

luminaire safety when applied to the

luminaire and component safety when

applied to the components. Different labels

and markings are used for various applica-

tions, but all make use of the trademark UL

circle.)

INTERIOR LIGHTING FOR DESIGNERS

COMPARATIVE FLUORESCENT LAMP-BALLAST SYSTEMS

Ballast kind

Typical input power

(W)

Typical ballast

factor

System efficiency

(Lumens/W)

Two F32T8/RS lamps, 32 W each

electromagnetic energy-efficient

electromagnetic heater-cutout

electronic ballast rapid-start

electronic ballast instant-start

70

61

62

63

0.94

0.86

0.88

0.95

78

82

82

87

Two F40T12/RS/ES lamps, 34 W each

electromagnetic energy-efficient

electromagnetic heater-cutout

electronic ballast rapid-start

72

58

60

0.87

0.81

0.85

68

78

79