What's the difference between a PoE injector and a PoE midspan?
A single-port injector adds power to one non-PoE port (or one cable run) and is ideal for retrofits or remote devices. A midspan is a rack or desktop unit with 4–24 ports that injects power into a bank of existing switch ports, scaling power without replacing the switch. Both use the same IEEE PoE standards; choice depends on scale and convenience.
Can I use a standard PoE injector for a PTZ camera?
No. Standard PoE (802.3af, 15.4W) is insufficient for pan-tilt-zoom motors, which typically draw 25–60W under motion. Use PoE+ (30W) or PoE++ (60W+) injectors rated for the camera's peak load. Check the PTZ datasheet for maximum power draw, including fan/heater in extreme conditions.
How do I prevent voltage drop on long cable runs?
Use higher-power injectors (90W+ output compresses voltage regulation window), upgrade to thicker Ethernet cable (10 AWG vs. standard 24 AWG), or install a second injector mid-run. For runs over 300 feet, test end-of-line voltage under load; aim for ≥44V DC at the farthest device. See our budget planning guide for voltage drop math.
Should I buy managed or unmanaged injectors?
Unmanaged injectors are cheaper ($50–150) but offer no visibility; use them for small, stable deployments. Managed injectors ($200–600) provide SNMP monitoring, per-port power limits, and email alerts—essential for multi-site, compliance-heavy, or dynamic environments. ROI is fast in larger systems.
What surge protection do I need for outdoor installations?
Outdoor PoE runs must include TVS (transient voltage suppression) diodes and fused inputs in the injector, plus Ethernet surge arrestors at the camera end. Industrial-rated injectors from Speco and Altronix include built-in surge protection; standard units do not. Lightning risk is real—don't skip it.
Can a single injector power multiple devices in series?
No. PoE is point-to-point: one injector powers one cable/device pair (or one midspan port powers one switch port + all devices behind it). You cannot daisy-chain injectors or passively extend PoE down a cable. Use Ethernet extenders for very long runs beyond PoE cable limits.
