DS-3E1520P-EI/M

Two limits apply: the number of PoE ports, and the total PoE budget in watts. Add up the maximum power of each camera from its datasheet and keep about 20% spare. Example: 16 cameras at 6 W each need 96 W, plus 20% is about 115 W, so a switch with a 125 W budget or more is right. A PoE port (802.3af) gives up to 15.4 W and a PoE+ port (802.3at) up to 30 W. PTZ cameras and cameras with heaters, strong IR or strobe lights need PoE+ or Hi-PoE (802.3bt). Not sure? Send us your camera list and we size it for you.

A normal network cable run is limited to 100 m (330 ft). In long-range (extend) mode the switch lowers the port speed to 10 Mbps, so data and power can travel up to 300 m (1,000 ft) on one good quality copper Cat6 cable. 10 Mbps is enough for one camera, so use this mode for one camera per port, for example at a far gate or along a boundary wall. For longer runs use fiber with SFP modules.

Unmanaged switches are plug and play, with nothing to set up: good for small systems. Smart (web managed) switches add a web page and app view for VLANs, port status, cable checks and, on many models, PoE watchdog, so you can find and fix problems from your desk. Managed (Layer 2+ or Layer 3) switches add full control, routing and ring protection for large sites, campuses and city projects. For most CCTV jobs with 8 to 48 cameras, a smart PoE switch is the best value. Ask us if you are not sure.

SFP and SFP+ ports take a small plug-in fiber module, sold separately. Use them to link the switch to the NVR room or main switch when the distance is over 100 m (330 ft), or between buildings. Fiber carries no electricity, so it also stops surges travelling between buildings. Choose single-mode or multi-mode modules to match your fiber cable, and use a matching pair of modules at the two ends. Ask us for the right modules and cable.