Unit 3-2 Lesson 11
A basic understanding of circuits is an aid to understanding the forming of possible temporary current paths through the worker. Death may be the result of body current flow. Select one: True False
True
A portable conductive mat can be used to limit the hazardous voltage drop across an underground worker caused by the voltage gradient at the underground site. Select one: True False
True
A common problem when cutting URD cables is ? . a. cable misidentification b. interruption of neutral current c. maintaining ground continuity d. providing a trip current path
A
A worker making a mid-span splice is not protected by the bonded conductive mat while ? . a. removing the cable and neutral bonding connections b. removing the semi-conductive cable layer c. replacing the cable jacket d. stripping the cable insulation
A
Before making a mid-span repair to a damaged cable, one cable end elbow is parked on a grounded stand-off bushing and the other is ? . a. also parked on a grounded bushing b. bonded to a conductive mat c. connected to a temporary ground rod d. parked on an insulated stand-off
A
Once a cable has been deenergized and the elbows ? , it is considered isolated and safe to proceed with the work. a. parked on grounded bushings b. parked on insulated stand-off bushings c. pulled and floating in the clear d. spiked
A
When working around pad-mount switches and transformers, a portable conductive mat can be used to provide ? protection. a. equipotential zone b. isolation c. multi-point grounding d. single-point grounding
A
The use of a conductive mat when making a mid-span splice is an example of the ? protection method. a. barricading b. equipotential zone c. insulation d. isolation
B
By construction design, an underground cable is a ? , so it must be discharged before handling. a. limit inductor b. shunt reactor c. tubular capacitor d. wave trap
C
In this vault test, the worker in the vault was touching the tank of a transformer with an ungrounded case. The concentric neutral was continuous back to the source. When the circuit was energized, the worker ? . a. became part of the system and lived b. survived because the vault was ungrounded c. voltage drop was a potentially fatal (748 V) d. voltage drop was only 1.5 V
C
Special hazards regarding underground work are buried problems that cannot be seen. Unseen problems include misidentified cables and ? . a. bushing surface current leakage b. improperly seated elbows c. leaking pad-mount transformers d. missing concentric neutrals
D
Incorrect phase identification at terminals is rare, and very few accidents have resulted from these kind of mistakes. Select one: True False
False
One of the vault tests conducted proved that when a bonded conductive mat was placed below the worker and the neutral switch was open, fatal body currents would flow. Select one: True False
False
The underground vault test results in the reference material determined that if the neutral is present, it is safe to assume it is continuous to the source. Select one: True False
False
When isolating underground cables, elbows can be pulled and transferred to grounded bushings with voltage-rated rubber gloves or hot sticks. Select one: True False
False
Spiking an insulated cable ensures it is electrically isolated before the insulation is opened. Select one: True False
True
The protection methods used in underground maintenance are limited to insulation and equipotential zones. Select one: True False
True
The series of vault tests prove that when a bonded conductive mat was used to create an equipotential zone, the voltage across the worker was held to a very low level. Select one: True False
True
Where equipotential grounding is impractical, underground distribution protection can be provided with voltage rated rubber gloves and blankets. Select one: True False
True
While performing underground maintenance, insulation and equipotential zone protection methods are sometimes difficult to implement because of work areas and conditions. Select one: True False
True
