What are the voltage limits for SELV and PELV circuits?

The voltage limits for SELV (Separated Extra Low Voltage) and PELV (Protective Extra Low Voltage) circuits are set to ensure safety in electrical installations. For SELV circuits, the maximum voltage allowed is 25V AC or 60V DC. This low voltage level is crucial as it minimizes the risk of electric shock under normal conditions, making it a safe option for many applications where higher voltages could present a hazard.

PELV circuits, which are designed to provide additional safety measures into existing circuits, follow similar constraints, thereby supporting the same voltage standards as SELV. Both types of circuits are designed to maintain a high level of safety for users by ensuring that the voltages remain below these thresholds, making option A the correct one.

The other choices either exceed these safe limits or are not commonly recognized for SELV and PELV applications, highlighting the importance of adhering to the established voltage thresholds.