When planning a video surveillance system installation, there are maximum distances of how far you can run power cable to security cameras. There are length limits for both the coax video cable and the power cable. This article focuses on power cable distance limits by comparing the use of 12V DC vs 24V AC to power analog CCTV and HD over coax security cameras. Generally, coax cable for video can be run up to around 800 feet for analog CCTV and HD over coax cameras (farther if you use a video amplifier). You can learn more about coax video cable length limits here.
Most of the lesser expensive CCTV and HD over coax cameras use 12V DC. Most include an individual 12V DC power supply or can use a multi-camera power supply box. Many higher end commercial grade cameras come in dual voltage, which allows installers to use a 12V DC or 24VAC power supply. The advantage of using AC vs DC is that the power cable can be run much longer distances without power drop with AC. Like DC, multi-camera 24VAC power supply boxes and individual 24VAC power transformers are available.
To compare AC vs DC, I used a voltmeter to measure how much power this dual voltage HD security camera draws with its infrared LEDs engaged. Security cameras draw more power with the IR LEDs illuminated. Being that it is a dual voltage camera, I measured the power draw with a 12V DC power supply, then with a 24VAC power supply. With 12V DC, this camera draws .39 amps of power. With 24VAC, it draws .27 amps of power.
Using this voltage drop calculator, I ran calculations to see when the 10% acceptable voltage drop would be reached with each voltage type. Using industry standard 18 gauge stranded power cable, power can be run up to 240 feet with a 12V DC power supply. However, when using a 24VAC power supply, the same 18 gauge power cable can be run up to 700 feet. Almost triple the distance!
Thicker Cable = Less Power Drop
You can run power longer distances if you use thicker gauge cable. Using the same camera in our above example, if I bump up the size of the power cable to 16 gauge instead of 18, this is what happens. I can run the 12V DC 380 feet with less than 10% power drop. I can run the 24 VAC up to 1,100 feet!
If you are installing security cameras at distances less than 200 feet away from their power source, it is typically safe to use 12V DC powered cameras. If the distance is greater, you should consider using dual voltage security cameras so that 24VAC power is an option. Before deciding, be sure to measure the length of your cable runs as accurately as possible and use this low voltage power drop calculator to make sure you choose the best power type and power cable size.
The voltage drop calculator is also available in our mobile app for iPhone and Android.
If you are looking for dual voltage / 24VAC security cameras, CCTV Camera Pros has some great choices available here. We supply these to DIY and professional installers around the world.
- 24VAC / Dual Voltage Analog CCTV Cameras
- 24VAC / Dual Voltage AHD Security Cameras
- 24 VAC / Dual Voltage HD-TVI Security Cameras
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