Terminology
A low resistance connection to earth that can be used to help trip protective devices in event of a fault as well as bleed off electrostatic induction.
What is a ground?
This is what Charles Dalziel used for testing in addition to dogs, pigs, sheep, and calves to chart the effects of electrical shock.
What are humans? (inmates)
As far as location of grounds, this is the most IMPORTANT THING to remember whenever grounding a transmission OR distribution line.
What is install grounds at the worksite?
The type of induction that is coupled capacitively with use of a proximity tester.
What is electric field (or electrostatic) induction?
These are the two electrical factors that combine to form electromagnetic induction.
What are current and voltage?
What are electric field (or electrostatic) induction and magnetic field induction?
What are capacitive coupling and magnetic coupling?
This is the default form of "plus one" that is created through the process of bonding all conductive elements present at the worksite together to an effective grounding scheme.
What is an EPZ?
This is what grounds are NOT, because they allow breakthrough voltage to appear at the worksite when a line comes energized.
What is a dam?
A wye-connected 69kV transmission line will have this much potential to ground.
What is 40,000 volts?
The term used in Ohio to describe required elements needed to protect above and beyond grounding (i.e., isolation, insulation, and EPZ) that will keep the lineman safe in most every situation he will ever encounter.
What is "Grounding Plus One"?
Magnitude, path of current, and this are the three most important factors in an electrical shock.
What is shock duration?
After establishing line clearance, this is the requirement immediately before AND after testing a line for absence of voltage.
What is test the tester on a known energy source?
The type of induction that is coupled magnetically and surrounds energized lines with current running through the circuit.
What is magnetic induction?
This is the type of circuit that electromagnetic induction is always seeking to form.
What is circulating current?
This is the form of "plus one" that can be used in lieu of an EPZ in numerous situations on distribution and transmission lines if contact with the body can be avoided.
What is insulation? (i.e., rubber gloves)
This is the electrical path that current flows in every circuit and the reason it is so necessary to have clean low resistance connections.
What is in every parallel path inversely proportional to the resistance in that path?
This is what will NOT trip a wye circuit in a protective grounding scheme in the event of a fault.
What is a screw or driven ground?
Note: if hot line tag is used, the circuit will open if the resistance is adequate for current to exceed the threshold.
The term that OSHA uses to describe the voltage rise when a grounded object comes in contact with an energy source.
What is "Energized Grounded"?
The energy source that linemen must protect against which will more often kill a contact victim than the default source due to typical shock duration.
What is induction or backfeed?
When all conductors in a circuit have been severed and both sides are effectively grounded, this is required when making the first connection.
What is the use of insulation such as rubber gloves or install a jumper with a live line tool?
This is what absolutely must be done prior to cutting open a grounded line that has bracket grounding installed and is running parallel with another energized distribution or transmission line.
What is jumper across the open point?
When working on a circuit with a voltage at or near zero but with current running through it, this is the one thing that must be avoided.
What is opening the circuit and getting between it?
This is the year that equipotential grounding first became an OSHA standard, even though Bonneville Power Administration initially proved its necessity in 1955.
What is 1994?
Electrical contact over this threshold of voltage will create an entry and exit wound and lower the skin resistance to 500 ohms.
What is 600 volts?
When working on a de-energized transmission circuit with induction present from another transmission line, this must be an important part of the protection plan when a static wire is not present at the site and a driven ground serves as the sole ground source.
What is the use of insulation or rubber gloves?
This is what physically happens with a ground chain during a fault on a circuit that has been effectively grounded when the fault current exceeds 15,000 amps.
What is "whipping" of grounds?
This is the only exception to "certain death" during a 2750mA electrical contact or greater for at least 2 cycles.
What is the susceptible phase of the heart cycle?
When multiple transmission systems are tied together, this factor can go very high and must be calculated and the proper size of grounds must be determined and installed.
What is fault current?
This is the set of grounds that will open the circuit when circulating current is present with more than one ground installed.
What is the second to last set of grounds?
When electromagnetic induction is present, this is how close system grounds need to be installed when using an EPZ.
What is at the exact location or structure being worked on?
When no induction is present anywhere on the circuit, an EPZ can be utilized as long as the protective ground is installed within this distance. Otherwise, insulation is required.
What is one span?
This is what the body becomes when working in the vicinity of energized transmission lines, actually energizing the lineman's body.
What is a capacitor?
When working on a 3-wire Delta connected transmission line with no static wire present at the worksite, re-energization from this other type of circuit must still be protected against.
What is a wye connected circuit? (transmission or distribution)
This is the electrical principle that makes it is so important to clean your ground clamps and clean the conductors prior to installation of grounds.
What is the principle of unequal resistors in parallel?
This is the let-go threshold for an electrical shock for a male.
What is 16 mA?
This is one direct AND one indirect way that a line can become re-energized after effectively grounding it.
Direct: What is physical contact with the default source or any type of foreign source?
Indirect: What is induction from a nearby energized line or lightning?
This is the conductor on a wye distribution system that a bracket grounded transmission circuit with circulating current running through it mimics.
What is a primary neutral conductor?
These are three things that affect the degree of hazard that electromagnetic induction presents to the line crew.
Any 3 of these
a. magnitude of current
b. distance lines run parallel
c. distance between the source of induction and the line being affected.
d. nominal voltage.
e. worksite distance from parallel lines
f. how and where grounds are placed
The reason that a "Plus One" scheme is required is because of induced current AND the fact that a grounded line can become energized to this percentage of nominal voltage upon direct contact with an energy source.
What is 17-24%?
This is the percentage that a parallel ground must be reduced when the grounds are installed just 10" apart.
What is 90%?
This is one of three reasons why most Bulk Electrical Systems (BES) on transmission are usually connected in a Wye/Wye configuration.
What is one of the three following reasons:
1. No phase angle displacements
2. Fewer turns in windings needed to create excitation in the core.
3. Less insulation at the neutral end of the winding is required.