1. A connection between metal structures, cabinets, cases, etc. which is required to prevent electrical shock hazard to personnel. 2. Safety ground is not a signal reference point.

The local earth ground. The earth ground which grounds the neutral return A system may be earth grounded as many times as needed.

An alternate path of return current, during a fault condition, for the purpose of tripping a circuit breaker. Also, the means of establishing a load at earth level. NEC refers to it as equipment grounding conductor.