What are Lightning Arrestors and Do I Need Them?
Lightning arrestors are not meant to protect equipment from direct strikes, but rather from nearby lightning strikes that could build up enough charge to have over-voltage transients that can cause damage to the radio equipment.
There is not a Meraki SKU for lightning arrestors, but you may use the Cisco Aironet lightning arrestor with N connectors (AIR-ACC245LA-N) when required on outdoor Meraki wireless APs/antennas. The arrestor is designed to protect the radio equipment from static electricity and lightning-induced surges that travel on coaxial transmission lines (antenna cables). Refer to our reference guide for more information on AIR-ACC245LA-N.
These systems need to be properly grounded according to the hardware installation guides. Proper grounding should be completed or confirmed by qualified electricians.
Note: Lightning arrestors are needed where a nearby lightning strike could induce harmful conditions on a length of coax cable. If your installation with ANT-20 omnidirectional antennas does not leverage antenna extension cables, then there is no coaxial cable, and the antennas are directly attached to the AP. In this scenario there is no need to install a lightning arrestor as an inline barrel connector. It is still important however to make sure the whole unit (AP + directly attached omni antennas) is properly grounded via the chassis of the AP.
Note: If an installation involves mounting an AP outside and the antenna leads (coax cable extensions) are coming through a wall inside a building (or vice-versa), then each of the four antenna leads should have lightning arrestors (on each cable) prior to entering the building and properly taken to ground.
The main concern is protecting the equipment inside the building, and some installations may also call for lightning protection on the Ethernet cable entering the building as opposed to lightning arrestors on the antenna cables. Arrestors would be used where coaxial antenna cabling comes into a building and especially areas where there is a significant length of exposed outdoor coax cable. In other installations, it may be more appropriate to properly ground the outdoor AP and leverage an RJ45-based lightning/surge protector for Gateway-mode APs that are wired back to an access switch. Always consult with a WLAN specialist who can advise the proper grounding design for your specific installation.
https://documentation.meraki.com/MR/Other_Topics/Frequently_Asked_Questions_regarding_Cisco_Meraki_A...
I am not a Cisco Meraki employee. My suggestions are based on documentation of Meraki best practices and day-to-day experience.
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