Most security cameras use 12-volt power adapters. The voltage is low so that the cameras can be kept powered for long periods of time without using a lot of energy. The low voltage also helps to prevent the cameras from being damaged by power surges.
Most security cameras use 12 volt power supplies. Some higher end cameras may use 24 volt power supplies. The reason for this is that 12 volts is the standard voltage for most electronic devices and 24 volts is twice as powerful as 12 volts. This means that if you have a camera that uses a 24 volt power supply, you will need to purchase a separate power supply for it.
Frequently Asked Question
What voltage do security cameras use?
How is a home alarm system wired?
Can you splice security camera wire?
Can you use Cat 6 cable for security cameras?
12V DC: The Most Common CCTV Camera Power Supply Voltage. Most common security cameras function under 12 voltages. In other words, an adapter with 12V is readily accessible to meet the needs of power supply for security cameras. 
A wireless control panel communicates with the monitoring center using a cellular connection. A wired control panel uses your home’s telephone line or Ethernet cable to connect to the monitoring center. 
The cables are color-coded, so strip them one at a time and splice each one individually to its corresponding wire on the opposite cable. You can solder them or crimp on small butt-type connectors, whichever you prefer. The wires are fine, so either option requires patience and a steady hand.25 Nov 2019 
A very common question regarding security cameras and installs is the type of cabling to use. Currently, 2 types of wiring are widely used for IP security cameras which are Cat6 or Cat5e twisted pair cabling.8 Dec 2016 
Security cameras use a variety of voltages, depending on the type of camera. For example, a typical home security camera uses 12 volts, while a professional security camera can use up to 24 volts.