Chapter 1 Flashcards
Clearing Lines and Equipment
What are the 3 Categories electrical linework fall into?
- ) Construction
- ) Maintenance
- ) Repair
What services may Utilities and Contractors provide?
Services for all three areas or may specialize in just a few tasks
What is a common saying throughout the industry?
“Linework is Linework”
What does Construction refer to?
Building new facilities.
What is Maintenance work?
Work performed on existing lines or equipment
How does repair differ from maintenance?
It typically involves an emergency situation.
What are some examples of Construction?
- Building new transmission lines
- Extending distribution lines
- Installing underground lines and equipment to feed a new housing development, or similar activities.
What are some examples of Maintenance?
- Replacing Conductors
- Changing out aging poles and structural members
- Replacing apparatus such regulators, capacitors, reclosers and more
What are some examples of Repairs?
- Restoring power during an unexpected outage
- Repairing storm damage
- Fixing poles hit by vehicles
- Repairing broken conductors or structures that require immediate attention
What does OSHA have for the Construction industry?
Rules and Regulations
What category does Maintenance and Repair fall under according to OSHA?
“General Industry” Regulations
What kind of work do Large Contractors typically perform?
Construction-orientated work for utilities
What kind of work do utilities focus on?
Maintenance and Repair
When would contractors may perform maintenance and repair?
When utilities can’t handle the work demand.
What did an industry expert recently estimate his transmission construction department perform at?
70% De-Energized Work
What did an industry expert recently estimate his distribution maintenance department perform at?
80% Energized Work
What are the two methods for working on a power delivery system?
- Energized
- De-Energized
What is Energized work?
Work performed when the line is “hot”
What does “hot” mean?
When the line is at its normal operating, or nominal, voltage.
What does Energized work require?
Specialized live-line tools and equipment that allow lineworkers to perform
What are three common work processes for Energized work?
- Hot Sticking
- Rubber Gloving
- Barehanding
How do these processes allow linework to be performed?
Without interrupting service to a utility’s customers.
What are some examples of De-Energized work?
- New construction of poles
- Substations
- Storm Restoration
- Connecting a new housing development
In the industry, the saying a line is De-Energized mean?
That certain specific steps have been taken to remove voltage from that line.
Lines are not De-Energized until all of what steps have been completed?
- Disconnect
- Test
- Properly Grounded
In De-Energized work what does Disconnect mean?
The lines and equipment from all normal sources of energy: all connections have been opened, locked and tagged. At this point, the line is disconnected but not yet De-Energized.
In De-Energized work what does Test mean?
Lines and equipment for the presence of voltage. This must occur before any grounding components are connected to the lines or equipment.
In De-Energized work what does Properly Ground mean?
Properly Ground the conductors (phases). Grounding provides low-resistance path to the best available ground, in case the line or equipment becomes accidentally energized.
What is the best definition of De-Energized?
The point at which all supply conductors have been tested to verify the absence of nominal voltage, and shunted together through the grounding process so that all supply conductors share the same as the.
What factors decide whether to work energized or De-Energized?
- Employee Safety
- Utility Demands
- Customer Expectations
- Construction Standards
- Equipment Availability
- Weather Conditions
- Qualifications of Personnel
What is important to understand about De-Energized lines?
They can become energized by unexpected or abnormal sources of energy.
What do workers who follow proper grounding procedures greatly enhance?
Their protection against abnormal sources of energy.
What are the two grounding procedures?
- Equipotential Zone (EPZ) Grounding is the preferred method for protecting the linework
- Bracket Grounding is used to trip out the circuit as quickly as possible
What does Bonding refer to?
Connecting and conductive item within the work space to the same potential as the grounded phases.
As simple as possible, explain EPZ Grounding.
The structure on which the lineworker is bonded together with the phases.
What does OSHA require of the employer?
To ensure that each qualified employee has demonstrated the ability to resolve problems to the subject matter, work, or project, and is trained and competent
What should you do if at anytime you are uneasy, or unsure whether a hazard exists?
STOP what you’re doing and elevate the concern to your crew leader or safety representative.
What analogy is often made to help explain electrical concepts?
Water-Related
What is a common misunderstanding about current?
Current takes the path of least resistance to an object of different potential.
How does electrical current compare to water?
They both take every path available to objects of different potentials.
When is a circuit complete?
When conductors connect a source to a load and then loop back to the source.
What does it mean if multiple loads are connected to the source?
There will multiple paths for current to flow.
How will current flow?
Through any and every path that complete the circuit.
What is the only thing that stop current from flowing?
Insulation that is able to contain the electrical pressure created by voltage.
What is the main focus when working on De-Energized lines?
Protecting workers in case the line becomes energized unexpectedly.
How is protection provided to workers working on De-Energized lines?
By installing protective grounds to limit the amount of current that the worker is exposed to on the job site.
What can proper use of Protective Grounding Equipment greatly enhance?
The safety of a lineworker who is contacting a line that becomes energized.
What are the two objectives, if met, they make Protective Grounding and Bonding effective?
- Minimize the time it takes to trip the circuit
- Limit the current flow and voltage drop across the lineworker’s body
What do these two core objectives apply two?
Every De-Energized application
- Overhead
- Underground
- Transmission
- Substations
What are the three principles lineworkers follow when performing energized work?
- ) Insulate
- ) Isolate
- ) Protect Against Second Point of Contact
When insulating for energized work, what kinds of equipment may be used?
- Hot Sticks
- Rubber Gloves/Sleeves
- Rubber/Plastic cover-up equipment to shield against current flow
When isolating for energized work, what is the procedure?
Create physical separation from any object of different potential.
In energized work, how would you protect yourself against a second point of contact?
Arrange the insulation and isolate the workers and tools so that anything that has a different potential than the item to be worked cannot be reached from the work position.
What is the ONLY way to completely prevent current flow through the lineworker?
Insulate and Isolation
What is the Second Point of Contact defined as?
The point at which current leaves the body during simultaneous contact between two or more objects of different potential.
When do lineworkers use isolation?
When working on systems that operate at distribution and subtransmission voltages.
Depending upon the nominal voltage of the circuit what kind of insulation is used?
- Rubber Insulating Gloves
- Insulated Hot Stick
If the insulation is compromised what is the only protection left?
Isolation
If Insulation and Isolation are compromised what happens?
There is no protection from the second point of contact.
What is rubber and plastic cover-up equipment not rated for?
Use on higher transmission voltages
When and why is barehand work a viable option?
On higher transmission voltages because the worker bonds onto the individual phase to be work, meaning that the worker is energized at the same potential as the phase.
What is the human body in relations to electricity?
An excellent conductor.
How is the human body an excellent conductor?
- 70% Water
- Nervous System uses electrical signals to make body function
- Blood, Bones and Muscles are filled with electrolytes like salt, which also conduct electricity
What did Professor Charles Dalziel of UC Berkeley learn?
That body types have different electrical resistance. He also created a scale showing how people and animals react to electrical current.
How much current does it take to put your heart in v-fib?
- 1/3 of 1 Amp
- 10%-70% of 1 Amp
- 100-700mA
Limiting the flow of current reaching the working to less than 1 Amp can be_____?
A Challenge.
What can lineworkers be exposed to?
Accidental currents of several thousand amps at any work location, even on De-Energized lines.
The voltage (electric pressure) pushing the current increases what?
The chance of injury.
What is rule to live by in relations to current?
Current of any value, regardless of voltage, is enough to be fatal.
The power delivery industry developed what to help lineworkers protect themselves?
Procedures, PPE and tools for working on power lines.
What does OSHA require?
All employees exposed to electrical hazards to use industry-approved protective equipment and procedures.
What is today’s electrical grid network?
Complex and often congested.
What is critical to lineworker safety?
Knowing how to clear lines and equipment properly.
What does the word clearance refer to?
To the formal condition of a line, line section, or piece of equipment that has been disconnected (cleared) from all normal sources of energy.
How is clearance done?
By opening devices in the path of the normal flow of power.
Other names for a Clearance?
Hold-Off Clearance, Working Clearance, Lockout/Tagout, Line Clearance, Apparatus (or equipment) Clearance, or Outage
What Three roles involves a Clearance?
- ) Clearance Holder
- ) System Operator
- ) Field Operator
What is the Clearance Holder’s role?
Responsible for accomplishing the work in the field (Normally a crew leader). A clearance is issued to the clearance holder, and cannot end until the clearance holder releases the clearance.
What is the System Operator’s role?
Works at the utility’s operations center and has a system-wide perspective and control of the system in real time. This person gives permission for the clearance to occur, can operate devices remotely, and releases the line or apparatus to the clearance holder so the that work can be performed.
What is the Field Operator’s role?
Any employee in the field physically operating the apparatus or devices used to disconnect the lines or equipment. This is done at the direction of the system operator. (Troubleman, Switchman, Roving Operator, Station Operator, or other position)
What may smaller utilities do with for these responsibilities?
Merge them
What does a clearance involve?
The line or equipment that the crew will be working on.
What does does a clearance mean?
All normal energy sources connected to this site have been disconnected, all devices in the path of normal flow of power are opened, locked if possible, and tagged.
What is done immediately after the System Operator issues the clearance?
The clearance holder tests and grounds the line to prove that it is De-Energized.
When clearing lines and equipment, what are the three major objectives?
- ) Ensure the safety of all employees and the public.
- ) Minimize the negative impact on the electrical system.
- ) Minimize the number of customers who will be out of service.
How do you achieve these objectives?
- Ensure effective three-way communication between the system operator, the field operator(s), and the clearance holder.
- Accurately identify the line, line section, or piece of equipment
- Accurately identify 1) all sources of energy 2) the devices that will be used to disconnect these sources of energy, and 3) the status, or condition of these devices (open, closed, tagged.)
