What characterizes "effectively grounded" according to electrical standards?

"Effectively grounded" refers to the condition in which an electrical system or equipment is connected to the earth in such a way that it provides a low impedance path for fault currents. This low impedance connection allows any transient over-voltages or fault currents to safely dissipate into the ground, thereby protecting both equipment and personnel.

A low impedance connection is pivotal because it ensures that any fault current can flow freely to ground, minimizing the risk of electric shock and allowing protective devices, such as circuit breakers, to operate effectively. This connection enhances safety and performance by effectively stabilizing the voltage during transient conditions, thus preventing potential damage to the system.

In contrast, connections characterized by high impedance do not provide an effective path for fault current, leading to increased risk of electrical hazards. The presence of multiple ground connections, while possibly beneficial in some contexts, does not inherently ensure effective grounding if the connections do not meet the impedance criteria. Finally, systems that are not connected at all cannot comply with grounding standards, exposing equipment and users to electrical dangers. Therefore, the key characteristic of "effectively grounded" is the low impedance connection to earth.