Zmodo sells cables in lengths of 25ft, 50ft, 60ft, 99ft, 130ft, and 165ft. These cables range in thickness between 22AWG - 30AWG. The lower the AWG rating is, the thicker the cable is. Thicker cable will better protect the signal transmission from interference.
If your application requires that any number of cameras be more than 165 feet away from the DVR, you will need to power the camera locally, but have an option on which cable to use for the video signal. We do not recommend stringing two cables together to create one longer cable. (For example, coupling two 99ft cables together to create one 198ft cable) Coupling cables together in this way causes a massive loss of power and signal--which will deteriorate the image quality and cause damage to the camera over time.
One option for a long cable run would be to purchase a longer spool of RG59 cable, and install BNC Male to RCA RG59 adapters to each end of the RG59 cable. It is not recommended to run RG59 cable much longer than 250ft. Since RG-59 is used only for the video signal, you would need to power your camera directly with its own independent power adapter, as shown here:
Another option if your cameras need to be between 150ft - 1,000ft from your DVR location, is to use Video Baluns to run the video from your DVR. Video baluns can convert a video signal to a balanced signal, allowing the signal to transfer over Cat5 cable up to approximately 1,000ft. Power will still need to be plugged directly into the camera from a shorter distance.
It is recommended to hire a professionally licensed installed when installing cameras using video baluns of any kind, as insufficient power signal can result in damage to your cameras over time.