When determining the longest cable run and the number of cameras per power supply for a CCTV system using RG59 pure copper power cable, several factors come into play, including voltage drop and the power demands of the cameras. Here’s a general guideline based on common CCTV setups. Please also check out the recommendations at the bottom of this page, before deciding on purchasing your power supplies.
Voltage Drop Consideration:
– RG59 cable is commonly used for video transmission, but when powering cameras over long distances, voltage drop is a concern. As the cable run length increases, the voltage delivered to the camera decreases, potentially causing it to malfunction.
– To minimize voltage drop, the maximum recommended distance typically depends on the current drawn by each camera and the power supply.
Assumptions:
– Standard CCTV cameras generally consume around 12V and 0.5A each (6 watts per camera).
– LZ Pure copper RG59 power cable is used for both power and video transmission.
Longest Cable Run (Approximate):
– For 12V power supplies, the voltage drop over long distances can reduce the efficiency of the system. Below is a rough guide on the longest cable run per power supply for each scenario, assuming 0.5A per camera.
| Power Supply | Number of Cameras | Longest Cable Run (per camera) |
| 3 Amp (36W) | Up to 3 cameras | 120-150 feet (36-45 meters) |
|| 5 Amp (60W) | Up to 4 cameras | 150-200 feet (45-60 meters) |
| 10 Amp (120W) | Up to 8 cameras | 200-250 feet (60-75 meters) |
| 15 Amp (120W) | Up to 16 cameras | 250-300 feet (75-90 meters) |
| 20 Amp (240W) | Up to 16 cameras | 300-350 feet (90-105 meters) |
| 30 Amp (360W) | Up to 16 cameras | 350-400 feet (105-120 meters) |
Important Notes:
- Longer cable runs reduce the voltage reaching the camera due to resistance, so shorter runs are preferred.
- If using non-pure copper cables or mixing video baluns, the distances may vary.
- Power loss increases with longer runs, so it’s always advisable to measure actual voltage at the camera end of the cable.
- Different camera models can have different amperages.
- Infrared Cameras will draw more power when the Infrared mode is switched on E.g. Infrared on during night time, Camera installed in a dark room.
These estimates ensure that you avoid significant voltage drop and maintain camera performance.
Recommendations:
- It’s a good idea to purchase a power supply with a higher amp rating to account for any unexpected variables.
- This ensures your system has enough power for optimal performance and future expansion.
- For 16 Cameras or more, purchase 2 or more higher amp rating power supplies.
- For 16 Cameras or more, you can mix and match, purchase a lower amp for shorter cable runs, and a higher amp rating power supply for your longer cable runs.