Grounding Systems Flashcards
7 cards from real EETC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Grounding Systems flashcards as text
What is the purpose of equipotential bonding in a swimming pool area?
Answer: To eliminate voltage differences between conductive parts that a person could contact
Equipotential bonding ties all metallic parts together so no dangerous voltage difference exists between surfaces a person can simultaneously touch.
A concrete-encased electrode must contain at least how many feet of steel rebar or 4 AWG bare copper conductor?
Answer: 20 feet
NEC 250.52(A)(3) requires at least 20 feet of one or more steel reinforcing bars or 20 feet of bare copper conductor encased in concrete.
Which conductor connects the grounding electrode to the grounded conductor or equipment?
Answer: Grounding electrode conductor
The grounding electrode conductor (GEC) is the conductor that connects the grounding electrode system to the grounded conductor or to the equipment grounding conductor.
In a high-impedance grounded neutral system, what is the primary advantage over a solidly grounded system?
Answer: Allows continued operation during a single line-to-ground fault without tripping
High-impedance grounding limits ground fault current to a very low level, allowing the system to continue operating during a single ground fault while an alarm alerts personnel.
What is the maximum resistance to ground permitted for a made electrode (ground rod) per NEC 250.56 when a single rod is used?
Answer: 25 ohms
NEC 250.56 requires that if a single ground rod has a resistance to earth exceeding 25 ohms, an additional grounding electrode must be installed.
Which type of grounding electrode is also known as a 'Ufer ground'?
Answer: Concrete-encased electrode
The concrete-encased electrode was pioneered by Herbert G. Ufer and is commonly called a 'Ufer ground'; it uses rebar or copper in concrete footings.
When multiple grounding electrodes are used, they must be bonded together. What is this collection of electrodes called?
Answer: Grounding electrode system
NEC 250.50 requires that all electrodes present at a building or structure be bonded together to form the grounding electrode system.