Electrical Circuits and Wiring Diagrams 080204bB Flashcards
What does the E represent in Ohms law and what are the different names for it?
Voltage, EMF, Pressure
What does the I represent in Ohms law and what are the different names for it?
Amps, Flow, Current
What does the R represent in Ohms law and what are the different names for it?
Ohms, Resistance
What is Kirchhoffs law?
The sum of all voltages in a closed circuit is zero
Extra low voltage circuites are restricted to what?
Maximum of 30V and a maximum power level of 1000 VA
What 2 conditions must a class 2 circuit meet?
The voltage of the circuit must be 150V or less
The maximum power output of the circuit supply must be restricted to 100 VA
The benefits of limiting a circuit to Class 2 are what?
You are permitted to use conductors smaller than #14 AWG
The circuits often require a lower level of mechanical protection
How far away from a gas meter or relief decice must a switch or other electrical device be?
3’ (900mm)
When must a class 1 or class 2 circuit be grounded?
When supplied from a transformer with a secondary voltage ranging from 50V to 150V
When does a class 1 or 2 circuit not need to be grounded?
If the transformer has a secondary voltage of less than 50V and the primary voltage is 150 volts-to-ground or less
Where distance must a disconnect be installed in relation to a rooftop mechanical unit?
10’ (3m) and within sight
What are the 2 types of conductors that are approved by the CEC for Class 2 conditions of use?
LVT (extra-low-voltage control cable)
ELC (extra-low-voltage cable)
What kind of cable would you use to wire a 24V thermostat (heating control)?
LVT (extra-low-voltage control cable)
Whats another name for a load device on a circuit?
Actuator
What types of load devices are composed of a coil (the load device) and contacts (the controlling device)
Relays and magnetic contactors
What is one of the easiest ways to determine the way a piece of equipment works?
Study the schematic
What 3 components does an electrical circuit need in order to work?
Power source
Load
Conductors (joins the 2)
What type of diagram shows an eletrical circuit without regard to the physical location or actual appearance of the components?
Ladder diagram
What type of wiring diagram shows where the wires go, the route they take and the connection terminals?
Connection diagram (line diagram)
What are the function of the R and W on a thermostat?
R = power to stat
W = power from stat
What shows the maps or graphical representations of a process?
Flow charts (found in operating manual)
Control decices on a ladder diagram are shown in what state?
Normal positions with the load devices de-energized
