Which electrical system is required to be grounded?

The requirement for grounding in electrical systems is primarily concerned with ensuring safety and preventing faults that can lead to electric shock or fires. Grounding provides a pathway for electrical current to disperse safely into the earth in case of a fault, thereby protecting both equipment and individuals.

In a 120V, single-phase system, grounding is particularly important because it is typically used in residential and light commercial applications where there is a higher likelihood of human interaction with the electrical system. Grounding in these systems helps ensure that any exposed metal parts do not present a shock hazard, while also stabilizing the voltage during temporary fault conditions.

Generally, the National Electrical Code (NEC) mandates that low-voltage systems like the 120V system must be grounded, as they serve critical functions in households and are extensively used for various appliances and equipment. The other systems, while they may also have grounding requirements, typically pertain to higher voltage setups which have different codes and regulations concerning grounding methods. In summary, grounding a 120V, single-phase system is essential for safety, compliance with electrical codes, and protection against electrical hazards.