Grounding and Bonding Flashcards
6 cards from real 309A practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Grounding and Bonding flashcards as text
What is a concrete-encased grounding electrode (Ufer ground)?
Answer: A minimum 6 m of bare No. 4 AWG copper conductor encased in concrete foundation footing
A concrete-encased electrode (Ufer ground) consists of at least 6 m of bare No. 4 AWG copper conductor or 6 m of rebar encased in at least 50 mm of concrete in a building footing, providing excellent ground contact.
What is the purpose of a grounding ring around a building?
Answer: To establish a continuous grounding electrode encircling the building at the foundation level
A grounding ring consists of a bare copper conductor (minimum No. 2 AWG) buried at least 750 mm deep encircling the building, providing a comprehensive grounding electrode with low resistance.
What is the danger of a floating (ungrounded) neutral in a single-phase service?
Answer: Voltages become unbalanced, potentially causing overvoltage on lightly loaded circuits
A floating neutral causes the voltage to divide unevenly between the two legs of a 120/240 V service based on load. The lightly loaded leg receives excessive voltage that can destroy appliances and cause fires.
According to the CEC, when must a bonding conductor be installed with non-metallic conduit?
Answer: Always — a separate bonding conductor must be pulled through the conduit
Since non-metallic conduit (PVC) cannot serve as an equipment bonding path, a separate bonding conductor must always be installed within the conduit to provide fault current return path.
What is the purpose of exothermic welding (Cadweld) for grounding connections?
Answer: To create a permanent, molecularly bonded connection that will not loosen or corrode
Exothermic welding creates a molecular bond between conductors that is permanent, has lower resistance than the conductors themselves, and will not loosen or corrode, making it ideal for critical grounding connections.
What is the CEC requirement for bonding around non-metallic insulating joints in metal piping systems?
Answer: A bonding jumper must be installed around the insulating joint
CEC Rule 10-406 requires a bonding jumper to be installed around any insulating joint in a metal piping system to maintain electrical continuity of the bonding path throughout the piping system.