How do we protect against lightning and power surges?
Here are some basics.
See the PTP 800 User Guide for an excellent description of grounding and lightning protection. This section addresses lightning protection zones, grounding, and LPUs.
- Install equipment in the right places—understand lightning protection zones
- Grounding—don't forget to ground your equipment!
- Lightning protection units (LPUs)
- LPUs are designed for the type of transmission line they are protecting: coaxial cable, Ethernet cable, etc.
- LPUs are designed for the amount of power that the transmission line is carrying: pay attention to the DC voltage that the transmission line carries
Notice that in lightning prone areas of the world, we increase the number of grounding points.
LPUs may or may not protect against a direct strike; however, this is not their primary purpose. An LPU’s primary purpose is to protect against power surges due to lightning strikes that occur in an area around the protected device.
Do not “overprescribe” LPUs; for example, the PTP 820S and PTP 820C have built-in lightning protection, as do the PTP 820 PoE injectors. Since LPUs can affect the transmission line’s impedance, they may affect the line’s ability to carry high-frequency signals, like Gigabit Ethernet. If you need a link to carry Gigabit Ethernet, don’t add more lightning protection units than you need.
Pay attention to whether or not the LPU is designed to protect power-carrying signals and use the appropriate LPU.
In equipment with built-in lightning protection and multiple Ethernet ports, understand which ports are protected, and which ones are not. (For example, the PTP 820’s ETH1 is protected, but the PT 820’s ETH2 and ETH3 are not protected. Depending upon how you use them (fiber or Copper Ethernet), you may need to add additional lightning protection.)
I hope this helps!
Dave