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Working on Lines and Equipment > Chapter 2: Working on Lines and Equipment - Working on the Line - Possible Test Questions - WEEK 8 > Flashcards

Chapter 2: Working on Lines and Equipment - Working on the Line - Possible Test Questions - WEEK 8 Flashcards

1
Q

The steps to properly ground a line apply to overhead and underground circuits include:

A

1) Identify
2) Disconnect
3) Test
4) Clean
5) Ground

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2
Q

Test all lines and equipment before:

A

applying grounds

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3
Q

Multiple-range field intensity meter has a switch for selecting ________ ranges

A

-kilovolt

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4
Q

Audible Tester

A

The audible voltage detector (aka, hot horn or noisy tester) is an electronic instrument that attaches to a live-line tool. The unit is placed close to or in contact with the conductor (depending on the manufacturer) and will produce an audible warning and flashing light if voltage is detected.

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5
Q

The best grounding source depends on

A
  • your location and what is being cleared.
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6
Q

The deeper a temporary ground rod (TGR) is placed:

A
  • the less resistance it has
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7
Q

Static/Shielding Wire

A

This conductor is installed on transmission lines above the phase conductors for the purpose of intercepting lightning strikes. The grounding method depends on the structure type and the design of the line.

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8
Q

Anchor Rods

A

Some companies allow anchor rods to be used as a ground source due to their depth and availability throughout the system. Other companies prohibit this practice because a fault current may damage the anchor’s structural integrity. Know the policy for your employer or jurisdiction.

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9
Q

Metal Structures

A

On transmission lines, the resistance of the structure’s footing and its integrity as a ground source are unknown. This is true even if a permanent footing ground was installed during construction. When working on steel lattice towers, install a butt ground, which consists of a ground cable connecting the steel member to a TGR. Use a wire brush to clean the coating off galvanized steel. Refer to company policies about using a live-line tool to install butt grounds.

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10
Q

Choosing Ground Sources

A
  • All ground sources are not the same. Some are more reliable than others, and some are not available in every setting.
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11
Q

Choosing Ground Sources for overhead distribution:

A

1) Sub Station Ground Grid
2) System neutral
3) Temporary ground rod
4) Anchor rod (when allowed; do not use a guy-wire as a ground)

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12
Q

Choosing Ground Sources for transmission:

A
  1. Metal structure or tower
  2. Temporary ground rod
  3. Static/shielding wire
  4. Anchor rod (when allowed; never use a guy-wire as a ground)
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13
Q

A system neutral is not available as a ground source on:

A

transmission lines

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14
Q

Static/shielding wires are not always available on:

A
  • transmission lines.
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15
Q

Choosing Ground Sources for underground distribution:

A

With underground circuits, the ground source is readily available in the form of ground rods, equipment grounds, concentric neutrals, and the cable shielding.

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16
Q

EPZ is the best grounding method for

A
  • limiting current flow through the body
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17
Q

Insulating and isolating a lineworker is the only way to completely prevent

A
  • current from flowing through that lineworker.
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18
Q

Bracket grounding provides

A
  • low-resistance, short-circuited connection from the line to a ground source at key locations on one or both sides of the work site.
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19
Q

Bracket grounding is now used primarily to

A
  • trip the line’s protection devices as quickly as possible. This protects the worker and the system as a whole.
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20
Q

The Golden Rule of Grounding

A
  • Connect to the ground source first, and then connect to the conductor or equipment with a live-line tool. When removing the grounds, do the reverse: detach from the conductor before detaching from the ground source.
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21
Q

Walkthrough: Basic EPZ Installation (Distribution Poles)

A
  • Step 1 Test all phases for the presence of voltage
  • Step 2 Clean all conductors with a wire brush
  • Step 3 Instal cluster bracket and connect to ground source
  • Step 4 Connect grounding cable to cluster first, and then to any phase using live-line tool
  • Step 5 Connect grounding cable to grounded phase first and then to next closest phase
  • Step 6 Connect grounding cable to grounded phase first and then to next closest phase
22
Q

The Golden Rule of Grounding when removing grounds

A
  • perform steps 3 through 6 in reverse. Remove the conductor end first.
23
Q

Walkthrough: Basic EPZ Installation (Transmission Lines)

A
  • STEP 1 Test all phases for the presence of voltage.
  • STEP 2 Clean all conductors with wire brush.
  • STEP 3 Install cluster brackets and connect to ground source.
  • STEP 4 Connect grounding cables to cluster brackets first, and then to any phase using live-line tool. (It is preferable, but not required, to connect the middle phase first.)
  • STEP 5 Connect grounding cables to grounded phase first and then to other phases.
  • STEP 6 Wire brush shield wire and connect grounding cables from phases to shield wire.
24
Q

The minimum size for ground cable is

A
  • # 2 AWG copper.
25
Q

Ground Clamps:

A
  • Form the connection between the low-resistance ground cable and the conductor.
26
Q

Cluster Bracket

A
  • The grounding cluster bracket functions as a terminal point for the grounding cables and provides contact with the pole to establish the equipotential zone. Cluster brackets are also manufactured to mount on lattice towers if the grounding sets are not equipped with a tower-grounding clamp on one end.
27
Q

Running Grounds and Stringing Block Grounds

A
  • Running grounds protect lineworkers when stringing wire. They are installed on the conductor as it leaves the reel. Stringing block grounds provide direct grounding between the conductor or pulling line and the ground source. These blocks can be placed at key locations along the path of the wire stringing.
28
Q

Storage

A
  • Store grounding components in a way that protects them from damage. Storage bags work well and provide a convenient way to transport the grounds from the vehicle to the work site.
29
Q

Portable testers make the testing of grounding sets

A
  • quick and simple.
30
Q

Many companies are surprised to find that a large percentage of grounding sets used by their line crews do not pass the initial test. Common reasons for failure include:

A
  • Loose connections
  • Corroded connections
  • Corroded clamp jaws
  • Moisture intrusion in the cable
  • Improper crimping of the ferrule
31
Q

The decisions you make about where and how to install protective grounds and bonds depend on:

A
  • Your task and location.

- A job-specific grounding plan maps out how grounding sets will be applied for each worker and piece of equipment.

32
Q

The four components of a grounding plan include:

A

1) Creation of the equipotential zone (EPZ)
2) Grounding cable size
3) Grounding cable placement
4) Fault current

33
Q

Remember the Five Steps for Grounding Plan

A

1) Identify the section of line to be cleared.
2) Disconnect the section from all possible sources of electrical energy.
3) Test for the presence of voltage.
4) Clean all surfaces with a wire brush or approved cleaning agent to ensure a low-resistance connection.
5) Ground the section of line after it has been disconnected, tested, and cleaned-and before employee contact is made.

34
Q

Maintain minimum approach distance while

A
  • installing grounds.
35
Q

On metal lattice structures, the grounds may have to be installed:

A
  • From above the conductors because of the weight of the grounding cable. This is usually the case on structures carrying 345kV and higher.
36
Q

When removing grounds on lattice towers:

A
  • remove the conductor end of the grounding cable before removing the grounded end, which is attached to the tower.
37
Q

Protective grounding and bonding of overhead distribution occurs most commonly on:

A
  • four-wire wye circuits with a system neutral used as a ground source. Three-wire wye circuits and some three-wire delta circuits, both without a system neutral, require a temporary ground rod (TGR) for the ground source.
38
Q

A foreign ground is any conductive object that is:

A
  • 1) connected to ground,
  • 2) within your EPZ,
  • 3) not bonded to the EPZ.
  • Examples of foreign grounds include guy-wires, communication messengers, and aerial lifts.
39
Q

Maintaining Continuity:

A
  • If opening a conductor, install a grounding cable before cutting the conductor. This prevents the opened or cut side of the conductor from being separated from the protective grounds. It also ensures electrical continuity, which means an uninterrupted flow of current.
40
Q

Capacitor Banks:

A
  • Capacitors store energy and must be short-circuited by grounding prior to working on them. OSHA requires a five-minute wait after disconnecting the capacitor bank to bleed off any charge before short-circuiting and grounding the terminals.
41
Q

Grounding and Bonding Vehicles:

A
  • Testing indicates that even if a truck is grounded, current flow and voltage drop through a worker can cause injury. The best way to ensure protective equipment operates as fast as possible is to ground the vehicle to the system neutral.
42
Q

Personal Grounds:

A
  • Depending on the work being performed, workers have the option of using a personal ground-a ground cable connected just to the supply conductor, or phase being worked. A personal ground is allowed only between bracket grounds, and it must also establish an equipotential zone. Therefore, the structure or aerial lift or both must be bonded to the same ground connection.
43
Q

Portable Feedthru:

A
  • Used to disconnect, test, and ground a circuit, and available in both horizontal and vertical configurations to ease installation. The underground conductor to be grounded is positioned on one of the bushings and the grounding elbow can then be positioned on the other bushing.
44
Q

Grounding Elbow

A
  • The grounding elbow is sized for the fault current. The ground clamp is attached to the ground source, while the elbow end is placed on the portable feedthru along with the cable to be grounded. Grounding elbows also are manufactured in a three-way terminal assembly.
45
Q

Grounded Bushing:

A
  • Provides a temporary ground for elbows. Test the disconnect cable for voltage through the capacitance test point before installing it on the grounded bushing.
46
Q

Insulated Protective Cap:

A

Insulates, shields, and seals any load break bushing interface.

47
Q

Grounding Spike Clamp:

A
  • This penetrating clamp is typically used to prove that a cable is de-energized at the work location. When installed properly, the point will penetrate through the shielding to the conductor, creating a path to ground for the conductor. It is not used as a protective ground.
48
Q

EPZ Mat:

A
  • Also known as a grounding mat, these conductive mats help provide an EPZ between the work surface and the equipment. They are made of interconnected bare conductors, metallic or fiber surface mats, or welded wire grating.
49
Q

Cable identification is critical in underground systems because the cables cannot:

A
  • be physically traced from the clearance point.
50
Q

Job Briefing:

A

For common-sense safety-and to meet OSHA requirements-begin every job with a job briefing (sometimes called a tailboard). This improves the effectiveness of the grounding process by making sure every crew member clearly understands:

  • The locations of all possible sources of energy
  • Fault current levels
  • The overall grounding scheme
  • How many grounds are to be installed, and where
  • The size of grounding components
  • The specific installation and removal process
  • Who is responsible to install and remove the grounds

Working on Lines and Equipment (4 decks)

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