An RJ45 port is associated with Ethernet data and, in some systems, PoE power. Protection at this port is normally designed for transient surge and ESD events on the network cable. It is not the same function as a mains voltage protector that disconnects a 110V or 220V appliance supply.
1. What reaches an RJ45 cable
Long network cables can pick up fast transient energy from nearby lightning, switching, ground-potential differences or electrostatic discharge. Outdoor cameras, access points, building-to-building links and PoE devices are common situations where cable exposure deserves attention.
2. What an Ethernet protector does
A network surge protector provides a controlled path or clamping function for short transient events while maintaining the data connection. The design must consider data pairs, bandwidth, insertion loss, grounding and, for PoE, the power-delivery arrangement.
3. What it does not replace
- It does not normally monitor sustained 110V/220V over-voltage or under-voltage.
- It does not replace a mains-side voltage protector.
- It does not replace installation-level surge protection and earthing.
- It does not make an outdoor network device immune to a direct lightning strike.
4. PoE adds another design question
PoE carries DC power over the Ethernet cable. A compatible protector must preserve the intended data rate and PoE mode while handling transient stress on the relevant conductors. “RJ45 protected” is therefore too vague for a technical specification.
5. Buyer checklist
- Ethernet speed and cable category;
- PoE standard, voltage and power level;
- indoor or outdoor cable route;
- shielded or unshielded system;
- earthing/grounding method;
- where the protector is installed relative to the device and building entry.