1 Overhead Distribution 1 Basic Concepts - 3 Distribution Line Safety Flashcards
What does energized mean ?
Energized means that the line has a potential that is different than earth which is zero.
What does isolated mean?
Isolated means that line is electrically and mechanically is separated from all the sources of electrical potential.
What does de-energized mean?
De-energized means ( the line is dead ) the line is isolated and grounded so that the line has the same potential as ground which is zero.
Generally the grounds are installed how many spans farther from the line that you are working on?
One span apart.
How do we chose the right jumper clamps for the job?
The clamps are chosen by Maximum fault current that could be present on the utility system, the current carrying capacity the mechanical strength and also the size of the clamp hooks so that it could feed the conductor.
Why do we use wire brush when we install ground in the circuit?
The wire brush cleans the connection points of contamination and Corrosion and secures a positive low resistance connections.
Before connecting the ground. What steps must taking ?
The line must be de-energized and then tested for voltage presence with voltage tester ( tick tracer )
Why do we have to choose the shortest grounding cable that is physically possible to use and why do we have to coil up the slack and tight it a secure place like a pole?
The shorter the slack on the same rated wires equals to less resistance to ground and therefore it serves a better shield of protection. In the event that fault happens the excesses link of ground would move violently and could heart personnel and equipment around it.
What is Equipotential grounding (single-point grounding, Personal grounding or Equal potential grounding?
Equipotential grounding is a method that makes direct low resistance to earth and therefore limits a potential difference between the worker and the line he/she is working on.
How does the line man sets a zone of equipotential when climbing on top of the pole?
They use cluster bar that is connected to the ground road, neutral and all the phases on the pole. This way a zone of equipotential is created above the cluster bar where lineman is protected from a path of current to the ground since a sufficient low resistance path to the ground is present in reference to the line man and we know the current always takes the path of less resistance.
