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I've searched high and low for an definitive answer on this, including speaking with electricians, but still get conflicting opinions on this.

The goal: Install an outdoor wifi access point (AP), powered via PoE. (Specifically a Unifi UAP-AC-M-PRO)

Initial plan would be to just connect it like so:

      INDOORS | OUTDOORS
[ Switch ] ----------------- cat6 w/ PoE------------------- [ Access Point ]
              |

With the cat6 cable being rated for direct burial, and buried 18" down, directly or in conduit. And the AP mounted on a pole or tree.

However, Unifi's own instructions recommend having two surge protectors (labeled SP1 and SP2 below) (Specifically their ETH-SP-G2 model) One at where it enters the building. And another at the AP:

      INDOORS | OUTDOORS
[ Switch ] -----[SP1]------------ cat6 w/ PoE-------------------[SP2]--[ Access Point ]
              |

However, they don't specify what to ground these to. I would assume SP1 would ground to the building's ground, into an outlet box. But what would SP2 would ground to? The pole? A grounding rod?

As I've researched this, I find again and again warnings not to add an extra grounding rod, because it can create a new pathway for nearby lightning strikes to travel into the building, on its way over to the building's ground, passing through the networking equipment along the way.

So then that leads me to consider this option:


      INDOORS | OUTDOORS
[ Switch ] -----[SP]------------ cat6 w/ PoE--------------------[ Access Point ]
              |

Where I only do one surge protector, and do not attempt to add a new grounding rod. And possibly add a ethernet lightning suppressor before the switch.

Ultimately, I'd like to install this outside, but getting conflicting info on the best practices for this install. Hoping to get some clearer answers. Thanks

Note, I am also trying this question at the electrical stackexchange

cottonBallPaws
  • 111

3 Answers3

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Surge protectors are for protecting the equipment from surges in AC supply.

A surge protector (or spike suppressor, surge suppressor, surge diverter,[1] surge protection device (SPD) or transient voltage surge suppressor (TVSS) is an appliance or device intended to protect electrical devices from voltage spikes in alternating current (AC) circuits

From Wikipedia

Therefore they should be wired to the earth that's part of the mains supply.

You don't put it up on a pole, it needs to be where the power pack for the APs plugs into the mains. If you are using POE, then it's at the power pack for your POE switch. Because they are for surges, it does not matter whether the earths are tied together. Each device is being protected on its own.

I have always put surge protectors on all electronic devices.

Note that this has nothing to do with protection from lightning strikes (unless they create a surge in your mains supply).

You can also get whole of house devices. Here is an article on it Installing Surge Protection Devices

Rohit Gupta
  • 5,096
0

All grounds need to be centrally connected to avoid differences in voltage potential during lightning strikes. If you do not understand this concept then - NEVER add a second grounding location. In 99% of cases adding an additional ground will cause more hard than good. Your neutral and your ground need to be at the same voltage potential - Adding a second ground rod can change this unless you are avery good at RF engineering - don't do it.

JustG
  • 1
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I am trying to do, from what it sounds like, the exact same thing you are trying to do.

I also have received conflicting information from electricians, IT specialists, and even ISPs.

However a very helpful article that I came across from True cable can be found here: https://www.truecable.com/blogs/cable-academy/when-lightning-strikes-ethernet-data-cable-and-lightning-protection

With that said, I myself am not qualified to say if this is correct or not. However, I think the difference between your question and the article is that it is advised to have the AP grounded and then run a ground wire from the AP to your main ground via jumper which is typically located near the building where everything ties into. This, from my understanding, creates a ring set up where the voltage disparities will be all 'equal' as they are all connected.

If anyone has any more in-depth information in this regards I would love to hear in explained on my post so I can get a better understanding.

Mesh Network - Multiple APs - Indoor IT Equipment (Conesole, Switch, etc.) to Outdoor Pole Mounted APs

Heath Marsh
  • 11