3e Coordinate Electrical Flashcards
- What is represented by the diagram within the dashed line?
Which voltage types are
- single phase, two wire?
- single phase, three wire?
- three phase, four wire?
- What is represented by the line along the bottom of the diagram below?
1 - Utility company transformer
2 - 120V = single phase, two wire
3 - 120/208V single phase, three wire (120/240V residential)
4 - 120/208V three phase, four wire (all but largest installations)
5 - Grounded neutral
- What is the purpose of a ground neutral?
- How is the ground typically constructed?
- All electrical systems must be grounded to provide protection against shock + electrical fires.
- A rod or electrode firmly imbedded in the earth.
What is the sequence of flow for electrical current supplied to a building’s panel boards. (7)
- Main power line or transformer
- Service drop or underground SERVICE CONDUCTOR
- Service ENTRANCEconductor
- Watt-hour METER measure
- past GROUNDing rod
- service SWITCH (main disconnect to building)
- main SWITCHBOARD
building PANEL boards
What is the purpose of a transformer?
Used by med-large sized buildings to step down from a high-supply voltage to the service voltage.
A - List the 5 types of conduit shown below.
B - What 3 pieces of information are shown on the second conduit?
A
- Armored cable (aka BX cable)
- Nonmetallic sheathed cable (aka Romex) *moisture-resistant, flame-retardant
- Rigid Metal *steel tube joined by screwing into threaded hub
- Electrical metal tubing *thin walled, steel tube joined by compression or set screw couplings
- Flexible metal *used for motors/vibrating equip
B
- voltage class
- number & size of conductors
- type of insulation
A - What is the purpose of a panelboard?
B - Describe the various types of circuits fed by the panelboard. (4)
A - CONTROL, DISTRIBUTE, PROTECT similar branch circuits
B - Circuit types?
- BRANCH circuits
- GENERAL purpose outlets (lights / outlets)
- APPLIANCE circuits supply current to one or more outlets specifically intended for appliances
- INDIVIDUAL circuits supply current to only one piece of elec. equip.
- To avoid drop in voltage, what length should not be exceeded by a branch circuit?
- What % of a branch circuits capacity is reserved for flexibility?
- 100’ (30m)
- 20%
How is electrical current typ. supplied to doorbells, thermostats, intercoms, and HVAC systems?
LOW-VOLTAGE CIRCUITS
- current below 50V
- supplied by a stepdown transformer
List the typical mounting heights in the locations called out below:
- outlet above counter: 1220 (4’)
- switch on latch side of door 1220(4’) max
- 64(2.5”) min to door trim
- outlet above floor: 305 (12”) **455(18”) for accessibility
- No. of Convenience Outlets for residences
- No. of Convenience Outlets for Offices
- Living space: one every 3660(12’)
Countertops/kitchens: one every 1220(4’)
- one every 3050(10’)
OR one every 3.7m2(40ft2) for first 37m2(400ft2) and one every 9.3m2(100FT2)
Describe each of these outlets:
How many of these electrical plan symbols can you identify?
How many of these electrical plan symbols can you identify?
How many of these electrical plan symbols can you identify?
List and describe the 4 switch types.
- TOGGLE - lever knob opens/closes circuit (not shown below)
- 3-WAY - single-pole, double throw to control lights from 2 locations (see below)
- 4-WAY - used w 3-way to control lights from 3 locations (see below)
- DIMMER - rheostat or similar device for regulating the intensity of an ele. light wout affecting spatial distribution. (not shown below)