Installing Cable in Underground Vault or Manhole Flashcards
Cables should be sealed with paraffin or shrink wrap caps when? Why?
When left overnight or for more than eight hours.
Prevent moisture from entering the cable
Cables should be ? in a manner which will prevent the cable from ? at the point where it enters the manhole or vault.
Supported
Kinking
If a manhole is to have the cable looped between the entrance and the exit, the cable should circle the manhole at least ?
360 degrees
Where manholes are not to be looped, the cable should be routed on the walls ?
with the longest distance between points of entry and exit.
Cables should be arranged to avoid ?
interference with duct or worker entrances into the manhole.
Cables should be routed in a manner that will allow adequate room for bending and terminating the cables.
true
Cables must be supported in a way that will not result in cable weight being placed on the termination point.
true
Cable bending radius is to be at least ? the cable diameter.
12 times
Cables should not be directly fastened to support channels with wire or plastic ties.
true
Cables should be secured to racks with ? or mounted on a heavy-duty nonmetallic multi-mount cable support.
porcelain insulators and clamps
At least two racks should be installed in parallel on each manhole wall. The cable should not be supported by just one rack support in the manhole.
True
At least one spare hook should be installed at each cable rack position for future cable installations.
True
Cable racks should be secured to the walls of the manhole with 3∕8 inch-16 drop-in anchors with a rated pullout working capacity of at least 2,100 pounds.
true
Bolts installed in vaults and manholes should be made of 303 stainless steel, rated for use in underground devices.
True
The ? is the only part of a power cable that can take a fairly high pulling tension.
core conductor(s)
When pulling in cable using a wire-mesh grip with a swivel eye, the pulling tension is usually less than ? .
1,000lbs
One way a duct can be checked for proper diameter and obstructions is to ? through the conduit.
pull a flexible steel mandrel
If a cable is required to make a smooth low-friction 90° turn in a vault, a ? or lip-roller block would be used.
quadrant
A weak link installed at the pulling eye acts as a mechanical fuse and breaks apart before a cable is overstretched during pulling operations.
true
Depending on the jurisdiction, underground utility vaults (manholes) more than ? deep are considered to be an enclosed space.
4’
To avoid an explosion caused by a spark, before removing the cover, remote probes are used to test the atmosphere of an enclosed space for oxygen deficiency, ? and vapors.
flammable gases
When a blower is used to provide fresh air in an enclosed space such as a manhole, a blower with a capacity of ? cfm or greater is used.
1,000
Historically, about 60% of fatalities involving confined spaces occur when ? .
attendants perform a rescue
An impending fault is indicated when a cable in a vault has abnormalities such as oil or compound leaking, broken cable sheaths, hot localized surface temperatures, or swollen splices. When energized cables show symptoms of these types, the cable should be ? before anyone works in the vault.
de-energized
