Nlc WLE W2
Personal protective grounding cables must never be smaller than______copper.
#2AWG
anchor rod
-A metal rod driven deep into the ground in order to permanently secure a line or pole. Anchor rods are common elements of an electrical system. They are sometimes used as a ground source.
Four components of a grouding plan
1. Creation of the equipotential zone (EPZ) 2. Grounding cable size 3. Grounding cable placement 4. Fault current
What are the steps in the grounding process?
1. Identify the section tags, or other information sources. Consult with the system operator if of line to be cleared by using circuit maps, cable there is any confusion about what is being cleared, and when and how it will be done. or other tasks. All devices in the path of the flow of power are opened, may involve opening switches, standing off cable, removing jumpers, 2. Disconnect the section from all possible sources of electrical energy. This checked open, locked if possible, and tagged. This step was covered in Chapter 1 of this manual. first testing it, even if you are "sure" the crew did everything right during 3. Test the line for the presence of voltage. Do not contact the line without the clearance process. 4. Clean all connection points-including the clamps, conductors, cluster bracket, ground rods, anchors-prior to applying the grounds. This minimizes resistance and improves the effectiveness of the grounds. 5. Ground the section of line after it has been disconnected, tested, and cleaned-and before employee contact is made. Instal grounding components according to the grounding scheme and foilow the Golden Rule of Grounding . Remember: the line is not de-energized until it is grounded.
What are the two objectives for grounding lines and equipment?
1. Minimize the time it takes to trip the circuit. 2. Limit the current flow and voltage drop across the lineworker's body
Portable feedthrough
A _____ ______is used to isolate, test and ground a circuit.
grounding spike clamp
A clamp for underground systems that penetrates conductor shielding to create a short circuit. Used to prove that a cable has been disconnected before the cable is cut or spliced.
system neutral
A four-wire distribution circuit that functions as a ground source. An extension of a substation ground grid, it is grounded at least four times per mile.
butt ground -
A ground connection consisting of a temporary ground rod and grounding cable that is attached to the base of a steel tower.
equipotential zone (EPZ) grounding
A low-resistance, short-circuited connection from the line to a ground source, connected through a cluster bracket. An EPZ reduces hazardous differences in electrical potential between all objects within the zone. It is the best grounding method for limiting current flow through the body. See also bracket grounding and cluster bracket.
EPZ mat
A mat made of conductive material (such as welded wire or bare conductors) that helps provide an EPZ for workers and equipment. Sometimes called a grounding mat.
grounding clamp
A metal clamp connected to a grounding cable. The clamp attaches to conductors or equipment. Common types of clamps are C-clamp, snap-on or duckbill, and tower clamps.
bracket grounding
A protective grounding method in which a low-resistance, short-circuited connection from the line to a ground source is placed on one or both sides of the work site. The purpose is to trip out the circuit as fast as possible. Bracket grounds do not protect the lineworker as well as an EPZ ground. See also equipotential zone (EPZ) grounding.
running ground
A roller system that grounds conductors as they are being installed. They are mounted to a housing that attaches to a grounding cable. See also stringing block ground.
temporary grounding rod (TGR)
A steel rod or screw placed deep in the earth to provide an effective grounding path for current flow.
cluster bracket
A terminal point for the grounding cable used for EPZ grounding. The cluster bracket attaches to the pole or lattice tower.
job briefing
An OSHA-required meeting held before every job or shift to ensure every crew member understands specific factors and responsibilities for that job.
continuity
An uninterrupted flow of electric current.
buzz testing
An unreliable method of testing for voltage on a conductor. It involves placing a metallic object near the conductor and listening for a buzzing noise.
What is the Golden Rule of Grounding? Why is it important to follow?
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. If you disconnect the ground first you can get hurt or worse
portable feedthru
Device used to park cables, test, and ground underground circuits.
Multirange Voltage Detector
Essentially a multiple-range field intensity meter, this instrument has a switch for selecting kilovolt ranges. Unlike voltmeters, this uses the field strength to estimate the line-to-line voltage. It is displayed on a meter or digital readout. Depending on the tool, there may be no audible indicator. All readings should be regarded as estimates. Can detect the presence of voltage through capacitance test points on underground elbow connectors. Working condition is easily checked. The user must apply the proper test to get a result.
Why should you avoid excessive slack when installing grounding cables?
Excess sleck can whip violently under fault conditions, threating workers.
According to the Golden Rule of Grounding, connect to the ground source
First
When grounding wye and delta distribution lines, what options are available as ground sources? List them, from most effective to least effective, for each system.
For overhead distribution: 1. Substation ground grid 2. System neutral 3. Temporary ground rod 4. Anchor rod (when allowed; do not use a guy-wire as a ground) For underground distribution: With underground circuits, the ground source is readily available in the form of ground rods, equipment grounds, concentric neutrals, and the cable shielding.
Ground set testers
Ground sets are exposed to moisture, chemicals, dirt, and temperature extremes during normal use. The insulation can be cut or scraped, and the clamps and ferrules damaged. Only testing can determine the resistance of the clamps and cable. Visual inspection is not good enough. Test the grounding periodically, and tag them with the test date. Testers are simple and quick to use. They place a voltage across the clamps of the grounding cables to determine the resistance that occurs based on a voltage drop.
Explain why ground testers are needed.
Ground sets are exposed to moisture, chemicals, dirt, and temperature extremes during normal use. The insulation can be cut or scraped, and the clamps and ferrules damaged. Only testing can determine the resistance of the clamps and cable. Visual inspection is not good enough. Test the grounding sets periodically, and tag them with the test date.
2. Portable _____ ______now make testing a simple task.
Ground testers
foreign ground
Grounded conductors or equipment that are within the equipotential zone, such as a down-guy, a communication messenger, or the grabbers of a digger derrick. Foreign grounds must be bonded to the EPZ grounding scheme.
_____ _____ _____ function as a terminal point for the grounding jumpers.
Grounding cluster brackets
5 important steps to properly ground a line,______,______,______,_____ and______
Identify, disconnect,test, clean and ground
grounding cable
Jacketed copper cable suitable for carrying fault current. OSHA requires that grounding cable not be smaller than #2 AWG copper. Cable for transmission grounds should be at least 2/0 copper.
grounding plan
Job-specific plan detailing the type of grounding sets to be applied to a work site, the number of grounds used, and where they will be applied. This should be covered during the job briefing.
Hot sticks
Live line tools are also referred to as
Why is it important to think about MAD when grounding?
Many lineworkers relate minimum approach distances with energized work, not de-energized work. This is risky because a disconnected line must be treated and respected as if it were energized until it is proven de-energized through testing and grounding. This is why OSHA requires grounding cables to be installed and removed with an insulated live-line tool: it helps the lineworker maintain minimum approach distance until the grounding process is complete.
Grounding plan
Maps out how grounding sets will be applied for each worker and piece of equipment
As an apprentice, you will you'll be doing alot of work on the ground. Part of that includes inspecting equipment. Describe how you will inspect grounding cables and clamps. What will you look for during this inspection?
Movable portions of ground clamps should be tight and void of any free-play. Eye screw of the ground clamp should not be bent. Contact area of the jaws should be clean and free of corrosion. Connection between the cable and clamp should be clean and tight. Cable should be free of broken strands (especially check near the clamp where bending is maximized). Cluster bracket should be free of cracks and warping.
Conductor, Grounds
Never separate a ______from the ______when removing jumpers or cutting wires.
2
OSHA regulations require that live line tools be removed from service every _____ years.
Explain the OSHA requirement for grounded capacitor banks.
OSHA requires a five-minute wait after disconnecting the capacitor bank to bleed off any charge before short-circuiting and grounding the terminals.
Which grounding method is preferred and why?
Over time, research proved that EPZ grounding provided better protection for the lineworker. If the line becomes accidentally energized with only bracket grounds installed, hazardous levels of current will flow through the lineworker's body. Even with an EPZ in place, small amounts of current will flow through the lineworker because the EPZ grounds and the lineworker form a parallel path to ground.
What are some ways to store grounding equipment to prevent damage?
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. Ground cables are durable, but should be protected against cuts, severe scrapes, and contact with any harmful chemicals or liquids.
List the possible grounding sources that can be used for protective grounds.
Substation ground grid, system neutral, Temporary Grounding rod (TGR), Static/Shielding Wire, Anchor Rods, Metal Structures
Substation Ground Grid
Substations have a well-designed, well-tested ground system designed to carry any fault current that may reach that station.
_____ _____are an effective way of protecting the lineworkers on the ground when stringing wire.
System neutral
How do you test for the presence of voltage on the line?
Test your lines before applying grounds. Like the job briefing, this is both common sense and an OSHA requirement. When testing the line for voltage, act as if it is energized. The line is not officially de-energized until you test and ground it. Use live-line tools to conduct the testing, Know the voltage level at the work location and the voltage range of your tester, Observe the minimum approach distance, Understand that the testers are not precise measurement devices-they indicate approximate voltage. Test with an approved tester-and verify that the tester is working-before applying any personal protective grounds. The following steps are industry best practices for using a tester: 1) test the tester to make sure it's working, 2) test the line for voltage, and then 3) test the tester one more time to make sure it is still working.
_______of _______and_____before applying personal protective grounds is critical and an OSHA requirement.
Testing, lines and equipment
System neutral
Tests have shown that connecting to the ______ ______provides the best opportunity for the protective equipment to operate.
Audible Tester
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. Runs on a battery. Simple to operate, and working condition is easily checked. Does not indicate the level of voltage.
minimum approach distance
The closest distance a worker is permitted to approach an energized object.
GROUNDING PROCESS
The steps to properly ground a line apply to overhead and underground circuits include: 1. Identify the section of line to be cleared by using circuit maps, cable tags, or other information sources. Consult with the system operator if there is any confusion about what is being cleared, and when and how it will be done. 2. Disconnect the section from all possible sources of electrical energy. This may involve opening switches, standing off cable, removing jumpers, or other tasks. All devices in the path of the flow of power are opened, checked open, locked if possible, and tagged. This step was covered in Chapter 1 of this manual. 3. Test the line for the presence of voltage. Do not contact the line without first testing it, even if you are "sure" the crew did everything right during the clearance process. 4. Clean all connection points-including the clamps, conductors, cluster bracket, ground rods, anchors-prior to applying the grounds. This minimizes resistance and improves the effectiveness of the grounds. 5. Ground the section of line after it has been disconnected, tested, and cleaned-and before employee contact is made. Install grounding components according to the grounding scheme and follow the Golden Rule of Grounding (see 2.1.6). Remember: the line is not de-energized until it is grounded.
Static/Shielding Wire
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.
By this point, you are familiar with a job briefing. However, when a job includes grounding, there are specific items to include as discussion points. What are they?
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
Underground Bushing Test Probe
This probe is an adapter for using common testers on underground systems. It is inserted into the bushing or placed in direct contact with capacitance test points. Employers may use testers manufactured specifically for underground systems.
How do you clean the line before installing grounds?
Use a wire brush to properly clean and prepare the conductor and any current-carrying grounding components prior to installation. When assigned to clean connection points. Cleaning should create an obvious visual change. on every contact surface- every part where the connections meet. Your goal is to decrease resistance by clearing a path for as much current to flow as possible. A half-hearted scrape of a wire brush is not enough. As an example, you should see a visual change equal to the difference between a dirty penny and a shiny penny.
Insulated protective cap
Used in underground systems to cover vacated bushings on transformers, switches, or other equipment. Rubber cover-up equipment designed
grounded bushing
Used in underground systems to provide a temporary ground for a grounding elbow.
grounding elbow
Used in underground systems to provide a temporary ground. Usually used with a portable feedthru.
Golden Rule of Grounding
When installing grounds, connect to the ground source first. Then use a live-line tool to connect the protective ground to the conductor or equipment. When removing grounds, remove the conductor end first and the ground source end last.
Cable Identification
With underground systems,_____ ______ is critical
What does it mean to ground something?
a good ground source to connect to. The best ground source to use depends on your location and the type of line or equipment being grounded.
Personal Grounds
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.
Running Grounds
are an effective way of protecting the lineworkers on the ground when stringing wire.
Live line tool
can suffer more abuse in storage and transportation than on the jobsite.
What is the disadvantage of using an anchor rod as a ground source?
fault current may damage the anchor's structural integrity. Know the policy for your employer or jurisdiction.
stringing block ground
ground - A device that grounds conductors as they are being installed. Unlike a running ground, stringing block grounds are installed at various locations along the path of the wire stringing. See also running ground.
Grounding spike clamp
is used to prove that a cable is de- energized at the work location.
Describe the equipotential zone grounding method.
provides a low-resistance, short- circuited connection from the line to a ground source. It creates a zone of protection to reduce hazardous differences in electrical potential between objects in the work area. EPZ is the best grounding method for limiting current flow through the body, and should be applied to the structure being worked on.
Describe the bracket grounding method.
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. It is now used primarily to trip the line's protection devices as quickly as possible. This protects the worker and the system as a whole.
OSHA
requires the use of live line tools to install and remove personal protective grounds.
Why is "buzz" testing an unsafe method for detecting line voltage?
the buzz may be masked by environmental noise (wind, traffic, nearby construction) or it may simply not be loud enough. Do not use this method of testing.
How does understanding the two objectives for grounding lines and equipment impact how you approach working on de-energized lines?
the focus is on protecting workers in case the line becomes energized unexpectedly. protective grounds designed involves a consistent series of basic actions. Each step must occur in the correct order, and the entire crew should work together to help ensure the safety of all employees and the public.
