Final answer:
Both a weatherproof cover and GFCI protection are necessary for a 125-volt receptacle used for servicing air conditioning equipment on the roof of a shopping center. These safeguard the electrical components and protect against electrical shock in outdoor environments.
Step-by-step explanation:
The student's question refers to the installation requirements for a 125-volt receptacle that will be used for servicing air conditioning equipment installed on the roof of a shopping center. According to the NEC (National Electrical Code), any such receptacle that is situated outdoors and exposed to weather must have both weatherproof protection and GFCI (Ground Fault Circuit Interrupter) protection. Therefore, the correct answer to the question is option III: Both I and II.
A weatherproof cover is necessary to protect the receptacle from rain, snow, and other environmental factors that could potentially damage the electrical components or pose a hazard. Additionally, GFCI protection is required to protect against electrical shock by quickly cutting off electric power if any loss of current is detected, which could occur if a person comes into contact with an unintended path for the current. These safety features are indispensable when installing electrical fittings in outdoor or potentially wet environments.