Grounding methods can vary and include solid grounding, impedance or resistance grounding, grounding through surge arresters and grounding through an inductor. The method is not always a matter of choice or a design consideration because, in many cases, it is required by the NEC.
Created by: Michael Johnston
1. The NEC specifies which electrical systems are required to be grounded, which systems are permitted to be grounded and which systems are not permitted to be grounded.
2. The term _____ means connected to ground or to a conductive body that extends the ground connection.
A. Bonded (bonding)
B. Grounded (grounding)
C. Grounded conductor
D. Grounding electrode
3. A 480-volt (V), three-phase, 3-wire, delta-connected system is always required to be grounded.
4. Where 30V AC systems are installed outdoors as overhead conductors, they _____ be grounded.
A. Are not required to
B. Are required to
C. Shall be permitted to
D. Shall not
5. Where a transformer secondary is 30V AC and the primary is supplied by an ungrounded source, the secondary must be grounded.
6. Which of the following circuits is required to be grounded?
A. 120V lighting circuits
B. Circuits for cranes over Class III locations
C. Isolated power systems for healthcare facilities
D. Lighting systems as provided in 411.6(A)
7. A _____ system does not have a neutral point.
A. 120/240V, single-phase, 3-wire
B. 480Y/277V, three-phase, 4-wire, wye-connected
C. 208Y/12 V, three-phase, 4-wire, wye-connected
D. 480V, three-phase, 3-wire, delta
E. 480Y/277V, three-phase, 4-wire, wye-connected
8. An AC system supplying premises wiring must be grounded where the maximum voltage to ground from any ungrounded conductor does not exceed 150V.
9. A phase-to-ground fault in an ungrounded system accidentally grounds the system and activates ground detectors.
10. Based on the NEC, _____V is the phase-to-ground voltage of the ungrounded conductors supplied by a 480V, three-phase, 3-wire, corner-grounded delta system.