Residential Wiring

What is a mast-type service entrance?

The most common method for installing an overhead service entrance. Most commonly used in areas where the electric utility distribution system has not been installed underground. Lies beneath the service head.

Where is panelboard A located?

The outside wall of the workshop

a. What size conductors supply panelboard B?

Three 3 AWG conductors

Why is bonding of service-entrance equipment necessary?

To have a complete circuit. There are two different types of fault conditions. To establish electrical continuity and conductivity.

Why must electrical systems and equipment be grounded?

To provide protection the system and equipment. Both must be grounded in order to limit voltage imposed by lighting, line surges, or unintentional contact with higher voltage lines that stabilize voltage to earth during normal operation.

What size overcurrent device protects the feeder conductors to panelboard A?

Type 2 SPD

How and where is the grounding electrode conductor attached to the water pipe?

With a listed ground clamp to the metal water pipping where the pipping comes through the basement wall.

a. Grounding electric conductor b. Main bonding jumper c. Grounded circuit conductor d. Equipment grounding conductor e. Underground service conductors (service Point at Transformer)

__C ____neutral conductor ____E ___ The term used to define the underground service-entrance conductors that run between the meter and the utilities connection. ________D __The conductor that runs the between the neutral bar in the main service equipment of the grounding electrode (water pipe, ground rod, etc.) _____A _____The bare copper conductor found in nonmetallic-sheathed cable

Part 1: According to the NEC definition of a wet location, a basement cement wall that is in direct contact with the earth is considered a wet location. A panelboard mounted on this wall must have at least: a. 1/4 in. b. 1/2 in. c. 1 in.

a. 1/4 in (6mm)

NEC 250.53 (D) (2) requires that a supplemental grounding electrode be provided if the available grounding electrode is: a. Metal underground water pipe b. Building steel c. Concrete encased ground

a. Metal underground water pipe

A surge protective device for the service is required to be of which of the following types? a. Type 1 b. Type 2 c. Type 3 d. Type 4

a. Type 1 b. Type 2

In general, systems are required to be grounded if the maximum voltage to ground does not exceed: a. 120 volts b. 150 volts c. 300 volts

b. 150 volts

Do the following grounding electrode conductors require mechanical protection?

-8 AWG: -6 AWG: -4 AWG:

Electric furnace:

-Circuit number: 1 and 3 -Ampere rating: 70A -Poles: two pole -Volts: -Conductor size: 4 AWG

When used as service equipment, a panelboard (load center) must be __________ that is suitable for use as a service equipment, 230.66. If the panelboard (load center) contains the main service disconnect, it must be clearly marked___________ 230.70 (B).

1. Marked 2. Service disconnect permanently

The circuit directory in a panelboard (may) (shall) be filled out according to NEC___________________

1. Shall 2. NEC 408.4

b. Overhead service conductor clearance over private sidewalks:

10 ft minimum

f. Overhead service conductor clearance from a fence that can be climbed on:

10 ft minimun

What size overcurrent device protects the feeder conductors to panelboard B?

100-ampere fuses in the 2-pole fused switch located at the service equipment

a. Overhead service conductor clearance over private driveway:

12 ft minimum

c. Overhead service conductor clearance over alleys:

18 ft minimum

a. What size conductors supply panelboard A?

2 AWG

What is the minimum size ungrounded conductors using copper conductors that have type THW insulation for the following residential electrical services? (200 amperes)

310.16: 3/0 310.12: 2/0

What is the minimum size ungrounded conductors using copper conductors that have type THW insulation for the following residential electrical services? (100 amperes)

310.16: 4 AWG 310.12: 3 AWG

What is the minimum size ungrounded conductors using copper conductors that have type THW insulation for the following residential electrical services? (400 amperes)

310.16: 500 310.12: 400

What size grounding electrode conductor is installed?

4 AWG copper grounding electrode conductor (GEC)

c. What type of main disconnect is provided in the residence in this book?

A 200-ampere meter base

a. The service head must be located (above) (below) the point where the service-drop conductors are spliced to the service-entrance conductors

Above

Is the grounding electrode conductor insulated, armored, or bare?

Armored

What type of wall is panelboard A fastened?

Concrete

Who is responsible for determining the service location?

Electric utility

Is this raceway run in the form of electrical metallic tubing or rigidi metal conduit?

Electrical metallic tubing (EMT)

c. Is this raceway run in the form of electrical metallic tubing or rigid conduit?

Electrical metallic tubing (EMT)

Where is panelboard B located?

In the utility room on the first floor

What special types of bushings are required on service entrances?

Insulating bushings and grounding/bonding insulated bushings

An equipment grounding conductor (is) (is not) required to be installed with feeder conductors to an outbuilding that is supplied by the service at the dwelling.

Is

When using rebars as the concrete-encased electrode, the rebars must be: a. insulated with plastic b. bonded together by the usual steel tie wires or other effective means.

NEC 250.52 (A) b. bonded together by the usual steel tie wires or other effective means

Define the service-drop conductors

NEC Article 100 The overhead conductors between the serving utility and the serving point. These conductors are installed, maintained, and owned by electrical utility.

Define the Service Point

NEC Article 100 The point of connection between the facilities of the serving utility and the premises wiring. Utility provides electricity from the supply side because they are giving it to us and we receive it on the load side.

b. What code section provides the answer to part (a)

NEC Article 230.26

a. Is the bare grounded neutral conductor of a service permitted to be buried directly in the ground?

No

When a conduit is extended through a roof, must it be guyed?

Only for extra support

b. What size conduit is installed?

Panelboard A: size 2 and size 1 for the other two Panelboard B: Size 3 and size 1

Part 2: How is this required space accomplished?

Raised mounting holes

When conduits pass through the wall from the outside to the inside, the conduit must be _______________ to prevent air circulation through the circuit.

Sealed with a putty-like compound (sealant)

Attic exhaust fan:

-Circuit number: 10 -Ampere rating: 15A -Poles: one pole -Volts: -Conductor size: 14 AWG

Attic lighting:

-Circuit number: 10 -Ampere rating: 15A -Poles: one pole -Volts: -Conductor size: 14 AWG

Living room receptacle outlets:

-Circuit number: 17 -Ampere rating: 15A -Poles: one-pole -Volts: -Conductor size: 14 AWG

Workbench receptacle outlets:

-Circuit number: 18 -Ampere rating: 20A -Poles: one pole -Volts: -Conductor size: 12 AWG

Counter-mounted cooking unit:

-Circuit number: 2 and 4 -Ampere rating: 40A -Poles: two pole -Volts: -Conductor size: 8 AWG

Water pump:

-Circuit number: 5 -Ampere rating: 20A -Poles: two pole -Volts: -Conductor size: 12 AWG

b. Are these devices required to be in one enclosure?

No. They are in separate enclosures but in the same location.

a. Service disconnect is permitted to consist of not more than how many switches or circuit breakers?

Not more than six switches or six circuit breakers mounted in separate enclosures at the same location.

a. What size and type of conductors are installed for the service in this text?

Panelboard A: 2 AWG, 4 AWG, and 6 AWG Panelboard B: 3 AWG and 8 AWG

Kitchen lighting:

-Circuit number: 7 -Ampere rating: 15A -Poles: one pole -Volts: -Conductor size: 14 AWG

Hydromassage tub:

-Circuit number: 9 -Ampere rating: 15A -Poles: one pole -Volts: -Conductor size: 14 AWG

b. What size raceway?

Number 2 0.2292 EMT and PVC conduit

b. What size raceway if installed?___________ Trade size 1____________

Number 3 0.2886 EMT and PVC

Copper-coated steel ground rods are the most commonly used grounding electrodes. These rods are required to: a. If not listed, be at least_________ in (______ mm) in diameter, 250.52 (A) (5) b. be driven to a depth of at least___________ ft (_______m) unless solid rock is encountered, in which case the rod may driven at a ________ degree angle, or it may be laid in a trench that is at least __________ ft (______m) deep, 250.53(G) c. be separated by at least ________ ft (__________ m) when more than one rod is driven, 250.53(A)(3) d. have a ground resistance of not over________ ohms for one rod, 250.53(A)(2) Exception

a. 5/8 inch (15.87 mm) b. 8 ft (2.44 m), 45 degree angle, and 750 mm (30 in deep c. 16 ft (1.8m) apart d. 25 ohms

To ensure a complete grounding electrode system: a. all grounding electrodes must be bonded together b. all metal pipes and conduits must be isolated from one another c. the service neutral is grounded to the water pipe only

a. all grounding electrodes must be bonded together