1. SERVICE ENTRANCE EQUIPMENT
INTRODUCTION
TRANSFORMERS
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
UNIT SUBSTATIONS
INTRODUCTION

2. SERVICE ENTRANCE EQUIPMENT
INTRODUCTION
TRANSFORMERS
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
UNIT SUBSTATIONS
SERVICE ENTRANCE EQUIPMENT:
TRANSFORMERS
METERS
MAIN DISCONNECT SWITCH
PANELBOARDS & OVERCURRENT PROTECTION
INTRODUCTION

3. SERVICE ENTRANCE EQUIPMENT
TRANSFORMERS
ELECTRICAL SUPPLY
DESCRIPTION
TYPES
SIZE & RATING
LOCATION
CUSTOMER-OWNED
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
TRANSFORMERS

4. SERVICE ENTRANCE EQUIPMENT
TRANSFORMERS
ELECTRICAL SUPPLY
DESCRIPTION
TYPES
SIZE & RATING
LOCATION
CUSTOMER-OWNED
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
DESCRIPTION:
DEVICE WHICH CHANGES THE VOLTAGE OF AN A-C CIRCUIT TO A HIGHER OR LOWER VALUE.
TRANSFORMERS

5. SERVICE ENTRANCE EQUIPMENT
TRANSFORMERS
ELECTRICAL SUPPLY
DESCRIPTION
TYPES
SIZE & RATING
LOCATION
CUSTOMER-OWNED
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
CONSTRUCTION:
AN IRON CORE ON WHICH TWO SEPARATE COILS ARE WOUND. THE COIL (WINDING) WITH THE GREATER NUMBER OF TURNS HAVING THE HIGHER VOLTAGE AND THE ONE WITH THE FEWER TURNS THE LOWER VOLTAGE.
TRANSFORMERS

6. SERVICE ENTRANCE EQUIPMENT
CONSTRUCTION:
TYPES:
STEP-UP: INCREASES VOLTAGE.
STEP-DOWN: DECREASES VOLTAGE
WINDINGS:
PRIMARY: THE WINDING WHICH IS USED FOR INPUT TO A TRANSFORMER.
SECONDARY: USED FOR OUTPUT. THE SECONDARY MAY BE DIVIDED INTO SEGMENTS, SO THAT THE OUTPUT VOLTAGE DEPENDS ON WHICH SEGMENTS ARE USED.
TRANSFORMERS
ELECTRICAL SUPPLY
DESCRIPTION
TYPES
SIZE & RATING
LOCATION
CUSTOMER-OWNED
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
TRANSFORMERS

7. SERVICE ENTRANCE EQUIPMENT
SINGLE-PHASE:
TWO-WIRE SECONDARY: HAS ONE WIRE GROUNDED, WHICH THEN BECOMES THE NEUTRAL.
THREE-WIRE SECONDARY: DIVIDED INTO TWO SEGMENTS. ONE LEAD IS AT THE END OF THE SECONDARY, A SECOND LEAD IS CONNECTED TO THE MIDPOINT OF THE SECONDARY & GROUNDED, & THE THIRD LEAD IS CONNECTED TO THE OTHER END OF THE SECONDARY.
TRANSFORMERS
ELECTRICAL SUPPLY
DESCRIPTION
TYPES
SIZE & RATING
LOCATION
CUSTOMER-OWNED
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
TRANSFORMERS

8. SERVICE ENTRANCE EQUIPMENT
TRANSFORMERS
ELECTRICAL SUPPLY
DESCRIPTION
TYPES
SIZE & RATING
LOCATION
CUSTOMER-OWNED
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
THREE-PHASE TRANSFORMERS

9. SERVICE ENTRANCE EQUIPMENT
TRANSFORMERS
ELECTRICAL SUPPLY
DESCRIPTION
TYPES
SIZE & RATING
LOCATION
CUSTOMER-OWNED
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
TRANSFORMERS

10. SERVICE ENTRANCE EQUIPMENT
OUTDOORS:
ADVANTAGES:
NO BUILDING SPACE REQUIRED.
REDUCED NOISE PROBLEMS WITHIN THE BUILDING.
LOWER COST.
EASE OF MAINTENANCE & REPLACEMENT.
NO INTERIOR HEAT GAIN PROBLEM.
OPPORTUNITY TO USE LOW-COST, LONG-LIFE OIL FILLED UNITS.
DISADVANTAGES:
VANDALISM.
DIRECT SUNLIGHT DECREASES OUTPUT BY INCREASING OPERATING TEMPERATURES.
OBJECTIONABLE APPEARANCE.
TRANSFORMERS
ELECTRICAL SUPPLY
DESCRIPTION
TYPES
SIZE & RATING
LOCATION
CUSTOMER-OWNED
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
TRANSFORMERS

11. SERVICE ENTRANCE EQUIPMENT
TRANSFORMERS
ELECTRICAL SUPPLY
DESCRIPTION
TYPES
SIZE & RATING
LOCATION
CUSTOMER-OWNED
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
INDOORS:
ADVANTAGES:
GREATER SECURITY.
EASIER TO CONCEAL (BASEMENT).
DISADVANTAGES:
HEAT GAIN (REQUIRING A FREE OPENING OF 3 SQ. IN. / KVA OR A LOUVER OF 8 SQ. IN / KVA)
MAY REQUIRE A FIRE RATED ENCLOSURE (VAULT)
TRANSFORMERS

12. SERVICE ENTRANCE EQUIPMENT
TRANSFORMERS
ELECTRICAL SUPPLY
DESCRIPTION
TYPES
SIZE & RATING
LOCATION
CUSTOMER-OWNED
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
CUSTOMER-OWNED TRANSFORMERS:
LARGE USERS:
COST SAVINGS IN BUYING LARGER QUANTITIES OF POWER AT THE DISTRIBUTION VOLTAGE FOR REDUCED RATES MORE THAN COMPENSATES FOR THE COST OF MAINTAINING THEIR OWN TRANSFORMERS.
SMALL USERS: SMALL SAVINGS WHICH NORMALLY DO NOT JUSTIFY HIGH INITIAL EXPENSE OF INSTALLING A TRANSFORMER.
TRANSFORMERS

13. SERVICE ENTRANCE EQUIPMENT
TRANSFORMERS
ELECTRICAL SUPPLY
DESCRIPTION
TYPES
SIZE & RATING
LOCATION
CUSTOMER-OWNED
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
CUT-OFF POINT FOR COST-EFFECTIVENESS:
UTILITY RATES.
TRANSFORMER COSTS.
AMOUNT OF ELECTRICITY USED.
TRANSFORMERS

14. SERVICE ENTRANCE EQUIPMENT
INTRODUCTION
TRANSFORMERS
METERS
DESCRIPTION
LOCATION
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
UNIT SUBSTATIONS
DESCRIPTION:
A DEVICE WHICH IS NORMALLY PROVIDED AT THE SERVICE ENTRANCE BY THE UTILITY COMPANY TO MEASURE HOW MUCH ELECTRICITY A FACILITY USES.
THE METER IS THE PROPERTY OF THE UTILITY.
METERS

15. SERVICE ENTRANCE EQUIPMENT
INTRODUCTION
TRANSFORMERS
METERS
DESCRIPTION
LOCATION
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
UNIT SUBSTATIONS
LOCATION:
ALWAYS INSERTED AHEAD OF THE MAIN SWITCH TO PREVENT THEM FROM BEING DISCONNECTED.
CAN BE INSIDE OR OUTSIDE, BUT THE UTILITY PERSONNEL MUST HAVE ACCESS TO AN INSIDE METER.
METERS

16. SERVICE ENTRANCE EQUIPMENT
DESCRIPTION:
MEANS OF DISCONNECTING AN ENTIRE BUILDING FROM THE ELECTRICAL SERVICE.
IT MAY BE MORE THAN ONE SWITCH, BUT NO MORE THAN SIX.
MAIN SWITCHES CONTROL ALL THE CIRCUITS IN THE BUILDING
INTRODUCTION
TRANSFORMERS
METERS
SERVICE DISCONNECT
DESCRIPTION
FUNCTION
LOCATION
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
UNIT SUBSTATIONS
SERVICE DISCONNECT

17. SERVICE ENTRANCE EQUIPMENT
INTRODUCTION
TRANSFORMERS
METERS
SERVICE DISCONNECT
DESCRIPTION
FUNCTION
LOCATION
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
UNIT SUBSTATIONS
FUNCTION:
DE-ENERGIZES ALL ELECTRICAL EQUIPMENT & CIRCUITS DURING MAJOR REPAIRS.
ALLOWS THE FIRE DEPARTMENT TO MAKE CERTAIN THAT THERE ARE NO LIVE WIRES INSIDE THE BUILDING.
LOCATION:
NEAR THE POINT OF SERVICE ENTRY INTO THE BUILDING.
SERVICE DISCONNECT

18. SERVICE ENTRANCE EQUIPMENT
DESCRIPTION:
DEVICES DESIGNED TO DISCONNECT A CIRCUIT AUTOMATICALLY WHENEVER THE CURRENT REACHES A PREDETERMINED VALUE THAT WOULD CAUSE A DANGEROUSLY HIGH TEMPERATURE IN THE CONDUCTOR.
HIGH TEMPERATURES CAN BE CAUSED BY SHORT CIRCUITS, EXCESSIVE DRAW OR A SURGE FROM THE UTILITY COMPANY.
INTRODUCTION
TRANSFORMERS
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
DESCRIPTION
FUNCTION
TYPES
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
UNIT SUBSTATIONS
OVERCURRENT PROTECTION

19. SERVICE ENTRANCE EQUIPMENT
INTRODUCTION
TRANSFORMERS
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
DESCRIPTION
FUNCTION
TYPES
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
UNIT SUBSTATIONS
FUNCTION:
PREVENTS ELECTRICAL FIRES.
PREVENTS POSSIBLE EXPLOSION.
PREVENTS DAMAGE TO EXPENSIVE EQUIPMENT.
OVERCURRENT PROTECTION

20. SERVICE ENTRANCE EQUIPMENT
INTRODUCTION
TRANSFORMERS
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
DESCRIPTION
FUNCTION
TYPES
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
UNIT SUBSTATIONS
FUSES:
CONTAIN A SHORT STRIP OF METAL WITH A LOW MELTING POINT. WHEN INSTALLED IN ITS FUSE-HOLDER, IT BECOMES A LINK IN THE CIRCUIT.
FUSES ARE ONE-TIME DEVICES.
MORE RELIABLE THAN CIRCUIT BREAKERS.
OVERCURRENT PROTECTION

21. SERVICE ENTRANCE EQUIPMENT
INTRODUCTION
TRANSFORMERS
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
DESCRIPTION
FUNCTION
TYPES
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
UNIT SUBSTATIONS
CIRCUIT BREAKERS:
CONTAIN A SIMPLE MECHANISM THAT TRIPS OPEN A CIRCUIT IN RESPONSE TO AN OVERLOAD CONDITION.
CONVENIENT: CAN BE RESET BY A MANUAL SWITCH TO RESTORE POWER.
CAN SERVICE AS A SWITCH TO TURN A CIRCUIT ON OR OFF.
MORE EXPENSIVE THAN FUSES TO INSTALL.
OVERCURRENT PROTECTION

22. SERVICE ENTRANCE EQUIPMENT
INTRODUCTION
TRANSFORMERS
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
DESCRIPTION & FUNCTION
LABELING
SWITCHGEAR & SWITCHBOARDS
UNIT SUBSTATIONS
DESCRIPTION:
THE BOX IN WHICH THE CIRCUIT PROTECTIVE DEVICES ARE GROUPED & FEED, ALONG WITH THE SERVICE DISCONNECT SWITCHES & SWITCHES TO MAJOR BRANCH LINES.
FUNCTION:
PANELBOARDS ACCEPT A RELATIVELY LARGE BLOCK OF POWER & DISTRIBUTE IT IN SMALLER BLOCKS.
PANELBOARDS

23. SERVICE ENTRANCE EQUIPMENT
INTRODUCTION
TRANSFORMERS
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
DESCRIPTION & FUNCTION
LABELING
SWITCHGEAR & SWITCHBOARDS
UNIT SUBSTATIONS
LABELING:
LP: LIGHTING PANEL
KP: KITCHEN PANEL
AHU: AIR HANDLING UNIT.
AC: AIR CONDITIONING
PANELBOARDS

24. SERVICE ENTRANCE EQUIPMENT
SWITCHBOARDS:
LARGE BUILDING OFTEN HAVE THEIR MAIN (PRIMARY) SWITCHES TOGETHER WITH THEIR SECONDARY (FEEDER) SWITCHES, & CIRCUIT PROTECTION DEVICES ALL ENCASED IN A FREESTANDING ASSEMBLY CALLED A SWITCHBOARD.
SWITCHGEAR:
SUCH A PACKAGE DESIGNED FOR HIGH-VOLTAGE (ABOVE 600-V)
SWITCHING EQUIPMENT IN MULTIPLE UNITS, NOT CONSOLIDATED IN A SINGLE UNIT.
INTRODUCTION
TRANSFORMERS
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
DESCRIPTION
LOCATION & SPACE REQUIREMENTS
UNIT SUBSTATIONS
SWITCHGEAR & SWITCHBOARDS

25. SERVICE ENTRANCE EQUIPMENT
INTRODUCTION
TRANSFORMERS
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
DESCRIPTION
LOCATION & SPACE REQUIREMENTS
UNIT SUBSTATIONS
LOCATION:
GENERALLY IN THE BASEMENT WITHIN A SEPARATE, WELL-VENTILATED ROOM DESIGNED FOR THAT PURPOSE.
SPACE REQUIREMENTS:
EXACT SPACE REQUIREMENTS ARE OBTAINED FROM THE ELECTRICAL CONSULTANT.
SWITCHGEAR & SWITCHBOARDS

26. SERVICE ENTRANCE EQUIPMENT
INTRODUCTION
TRANSFORMERS
METERS
SERVICE DISCONNECT
OVERCURRENT PROTECTION
PANELBOARDS
SWITCHGEAR & SWITCHBOARDS
UNIT SUBSTATIONS
DESCRIPTION:
A SINGLE PACKAGE COMBINING A STEP-DOWN TRANSFORMER WITH A COMPLETE SWITCHBOARD AND METERS.
ALSO CALLED A LOAD-CENTER SUBSTATION.
UNIT SUBSTATION