step and touch potential Flashcards
The “great myth” concerning grounding is that a connection to ?
the earth always gives a v = 0 condition
At distribution voltages, the voltage drop across the earth decreases by about ? for each two to three feet.
50%
The result of current flow through a resistance is that ?
a voltage drop across the resistance is developed
In a conductor, greater ? resistance.
length increases
What is the effect on the value of voltage at the earth’s surface as the distance from the connection point increases?
the voltage drops off rapidly
A worker stepping across the first two-foot space of energized earth would bridge a much higher voltage than a worker stepping over a similar three-foot span a great distance away.
true
At distribution voltages, the drop across the earth decreases by approximately ? for each two to three feet.
50%
The voltage at the earth’s connection point ? when compared with that of the overhead conductor it is attached to.
is nearly the same
If a worker is standing on a conductive ground mat and it should become energized, his or her first step off the mat will bridge ?
the maximum voltage drop
When high earth voltage is anticipated in a work area, the three methods that can be used to protect workers are to develop an equipotential zone, insulate, or ?
isolate
Two ways Qualified Electrical Workers can protect themselves from ground gradients include establishing an equipotential zone using a portable ground mat or ?
wearing rubber insulating overshoes
One way a groundman can encounter a touch potential hazard is by standing on a remote earth while touching a conductive item connected to the higher voltage.
true
Rubber overshoes worn to protect against touch and step potential are manufactured in accordance with ? standards.
astm
Insulation protects a worker at a work location if the insulation is installed between the worker and the source of current and is rated for the ?
voltage present
