CSLB C-10 Electrical ContractorWiring Methods and MaterialsEasy
What is the primary purpose of the grounding electrode conductor (GEC) at a dwelling service?
- ATo bond the metal water piping directly to the panelboard's neutral bus only
- BTo connect the grounded conductor and/or equipment grounding system to the grounding electrode system, limiting voltage from lightning or surges
- CTo carry the full load current of the service under normal operation
- DTo provide the normal current-carrying path for the neutral load current
Show answer & explanationAnswer & explanation
Correct answer: B. To connect the grounded conductor and/or equipment grounding system to the grounding electrode system, limiting voltage from lightning or surges
Per NEC 250.4(A)(1), the grounding electrode conductor connects the system to the earth to stabilize voltage and limit overvoltage from lightning, line surges, or unintentional contact with higher-voltage lines. It is not intended to carry normal or fault current.
Why the other options are wrong
- A. Water pipe bonding is only one part of the grounding electrode system, not the sole GEC function.
- C. Normal load current flows on ungrounded and grounded conductors, not the GEC.
- D. That describes the grounded (neutral) conductor's normal function, not the GEC.
Grounding Electrode Conductor (GEC)
A conductor connecting the grounded system conductor or equipment to the grounding electrode system to stabilize voltage to earth.
- Sized per Table 250.66
- Connects to electrodes such as ground rods, water pipe, or ufer ground
- Does not normally carry current except during a surge or fault event
Memory trick: GEC = 'Grounds Earth Connection' for voltage stability.