Add the normal operating current ratings for all connected 12 VDC devices, including cameras, access control hardware, and other accessories, then compare the total with the power supply’s 4 A output rating. At 12 VDC, 4 A represents 48 W, but allow capacity for startup or inrush current and battery charging when the unit includes a charger.

Input voltage depends on the power supply configuration: models in this category accept either low-voltage AC, such as 24 or 28 VAC, 115 VAC at 60 Hz, or 115/230 VAC at 50/60 Hz. Wire the source and 12 VDC load to the marked input and output terminals, observe DC polarity, and keep the connected load within the supply’s 4A total output rating.

Choose a single-output 12VDC 4A power supply when one device or a closely grouped load needs a shared power source and you do not need separate circuit protection. Choose a model with individually protected outputs when powering multiple access control, security, or CCTV devices, so each connected circuit can have its own fuse or resettable protection.

A 12VDC 4A power supply with battery backup charges a compatible sealed lead-acid or gel battery and can switch to standby battery power when AC input fails. AC failure monitoring, battery-presence monitoring, and low-battery supervision provide status information so connected security or access control equipment can be serviced when power conditions change.