EPEC Bronze 3 Job Aid
Typical Incandescent Bulb Construction
Lamp Identification system
EPEC Bronze 3 Job Aid
Types of Fluorescent Ballasts
Fluorescent ballasts are manufactured for four primary types of fluorescent lamps: preheat, rapid start, instant start, and programmed start.
•
In the “preheat” operation, the lamp’s electrodes are heated prior to initiating the discharge. A “starter switch” closes, permitting a current to flow through each electrode. The starter switch rapidly cools down, opening the switch and triggering the supply voltage across the arc tube, initiating the discharge. No auxiliary power is applied across the electrodes during operation.
•
In the “rapid‐start” operation, the lamp’s electrodes are heated prior to and during operation. The ballast transformer has two special secondary windings to provide the proper voltage to the electrodes.
•
In the “instant‐start” operation, the lamp’s electrodes are not heated prior to operation; instead, the ballast supplies a higher voltage, relative to the preheat and rapid‐start designs, to initiate the discharge across the unheated electrodes.
•
In the ”programmed‐start” operation, ballasts are able to precisely control the amount of starting current and the timing of the current flowing through the cathode. This very soft start allows the lamp to be turned on and off frequently with minimal impact on the cathode. Programmed start ballast are recommended for spaces where occupancy sensors are used. Sometimes this is referred to as “rapid start,” since the electrodes are being warmed prior to striking the lamp.
EPEC Bronze 3 Job Aid
Modes of Heating
•
•
•
Conduction is direct transmission of heat through two objects in contact; the metal handle of a frying pan conducts the heat from the burner and you feel it when you touch it (Figure 3‐20).
Convection occurs because warm air rises, as when heated air above a baseboard heater moves upward; convection current happens because warmer air will flow across the ceiling and cooler air will flow across the floor (see why smoke and heat detectors are mounted on the ceiling?) (Figure 3‐21).
Radiation is the heat transmitted by the sun and heats objects, not air, as in solar panels. Infrared lamps also provide radiant heat.
Motor Nameplate Data
1. Phase (PH)
2. Voltage
3. Horsepower (HP)
4. Frame (FR)
5. Full‐load Amps (FLA)
6. Speed/RPM
7. Frequency (Hertz)
8. Service Factor Amps (SFA)
9. Service factor
10. Maximum Ambient Degrees
11. Enclosure
EPEC Bronze 3 Job Aid
Ladder Diagram Symbols
L1, L2, L3
the line-side points of connection (from the source of power)
T1, T2, T3
motor terminals
normally open (N.O.) power contacts (3 M poles); the M indicates that
they are part of a motor starter. In this case, they are labeled M1 to
show it is part of the first motor starter.
normally open auxiliary contact (or holding contact), which keeps
power flowing to the coil even after the start button is released. Some
people call this the “memory contact” because the job is to
magnetically hold in the circuit, remembering the operator’s
instructions. It’s often labeled M or M1 to indicate which starter it
belongs to.
the symbol for a magnetic coil; the M indicates it is the coil for the
motor starter.
normally closed overload contact, identified O.L. as being part of the
O.L. overload relay.
the three heater elements (or coils) of the overload relay.
Three phase motor—a single-phase motor would be shown as
1, 2, 3
the numbers given to the wires and the points where they are
terminated. All points that are common will have the same number.
For example, “3” is common to one side of the start button, the coil,
and the auxiliary contact. Each of these points, and the wires
connecting them, would be given the designation “3” by the person
drawing the circuit.
wire connection
wire terminals
wire crossings
EPEC Bronze 3 Job Aid
Raceway Considerations
•
•
•
•
Conductor material
Ampacity required
Temperature rating of insulation
Derating of ampacity (if required) for
over three conductors in a raceway
• Adjust for cables exposed to sunlight
or other rooftop conditions
Steps to Select the Proper Raceway