NEC Test Quesions - Overhead Service Conductors

1. Minimum vertical clearance required to provide for 600V supply at the electrical service entrance of the building is:
a) 12 ft
b) 16 ft
c) 16 ft
d) 18 ft

Answer: A
Please Refer: NEC code: 230.24(B)

2. Service mast is provided with Braces or Guys for providing adequate strength for supporting service drop conductors:
a) True
b) False

A Please Refer NEC code: 230.28

3. Pumps and emergency systems can be supplied with additional number of services:
a) True
b) False

A Please Refer NEC code: 230.2(A)

4.Additional services shall be permitted to the buildings or structures where the capacity requirements are in excess of 1000 amperes at the supply voltage of 600 V or less:
a) True
b) False

B Please Refer NEC code: 230.2(C)

5. Ground conductors and service conductors shall be installed in the same raceway or service cable:
a) True
b) False

A Please Refer NEC code: 230.7

6. Service conductors installed as open conductors or multi-conductor cables without any overall jacket shall have a clearance not less than __ from windows, doors, balconies, ladders or stairs:
a) 2.5 ft
b) 3 ft
c) 4 ft
d) 6 ft

B Please Refer NEC code: 230.9(A)

7. Overhead conductors shall not be installed beneath the openings of the buildings from where material can be removed:
a) True
b) False

B Please Refer NEC code: 230.9(C)

8. Dried tree branches can be used as supporting structures for the over head service conductors:
a) True
b) False

B Please Refer NEC code: 230.10

9. The minimum vertical clearance ____ is required to be permitted for over head service conductors over public streets, alleys, roads and parking areas:
a) 12 ft
b) 14 ft
c) 16 ft
d) 18 ft

D Please Refer NEC code: 230.24(B)(4)

Temporary Wiring Electrical Safety Principles

Temporary Wiring:

The requirement for temporary wiring for power and lighting purpose includes provision of wire connections, junction boxes, over-current protection devices as well as the use of conductors. Temporary wiring does not have the meet all the requirements that permanent wiring meets. 

Temporary wiring is permitted to use:

Temporary electrical power and the lighting installations 600 volts, nominal or less may be used only:

• During and for remodeling, maintenance, repair or demolition of buildings, structures, or equipment and similar activities
• For experimental or development work and
• For a period not exceeding 90 days for Christmas decorative lighting, Carnivals and similar purposes

Temporary wiring over 600 volts, nominal may be used only during the periods of tests, experiments or emergencies

Feeder Circuits:

Feeders are the conductors that transmit power from service drop to the distribution panel board, or between the main disconnect and the branch circuit overload devices (Circuit breaker and fuses). Feeders for temporary wiring must originate inside an approved distribution center, such as panel board that is rated to the voltage and currents the system is expected to carry. Some equipments is manufactured specially for temporary use.

Feeders for temporary wiring must run as multi-conductor cords or cables, i.e, two or more conductors each with their own insulation run together in the same cord. One type of cable assembly has the hot conductors jacketed together and the neutral wrapped around them. The neutral is a special cable that is reinforced with the steel to provide the necessary support for the entire assembly

When the feeder conductors will not be subjected to physical damage, they can be installed as open conductors. However they must be installed on the insulating supports that are no more than 10 feet apart 

Branch circuits:

Branch circuits are the conductors between the last over-current device in an electrical system and the outlet such as receptacles, lighting outlets, and outlets for electrical equipment wired directly into a circuit. Branch circuits for temporary wiring must originate inside an approved panel board or power outlet that is rated for the voltages and currents that the system is expected to carry. As with feeders, branch circuit conductors can be contained within the multi-conductor cord or cable assemblies or they can be run as open conductors. If the conductors are run as open conductors, they must be securely attached every 10 feet at ceiling height. To avoid physical damage branch circuit conductors must never be placed on the floor

If a branch circuit supplies power to the receptacles or to fixed equipment through a system of open conductors, an additional conductor must be run with the circuit conductors to ground equipment

Receptacles:

Receptacles used in temporary wiring circuits must provide a connection for an equipment grounding conductor. Unless the receptacle is supplied by a metallic raceway that provides a continuous grounding path back to the source, a separate equipment grounding conductor must be placed in the branch circuit. There must be a good electrical connection between the receptacle grounding terminal and the equipment grounding conductor