Source
r/networking•
Walbort

Need advice on lightning protection on outdoor APs,cameras, etc.

A few months back, we had a bad lightning storm at one of our locations, and a lightning strike fried a few switches and some other equipment.

I was looking at something like this, but I'm curious if I would need two devices (it's sold as a kit of 2) on each end of the run as suggested, if I'm only really interested in protecting the LAN equipment upstream.

For double the cost, I want to know how much extra protection I'm getting by putting the second lightning protector next to the outdoor device, instead of only next to the switch.

Edit: Formatting

Posted Aug 20, 2018, 5:45 PM UTC · edited

111
ZeniChan•

Typically from what I have seen. If lightning hits something to travel down an Ethernet cable, it has hit the device at the end that is exposed and blown it to pieces. The only time I have seen both ends lightning protected is when an aerial span of Ethernet cable has been run between buildings and you install lightning protection at both ends.

5
pdoten•

This all depends on your level of risk. If you want to just protect the network switch from ingress and are willing to stock spare outdoor APs and cameras, then one should do it. The reason for both is that if the cable picks up the surge then both ends are protected.

3
WalbortOP•

This is what I figured. I don't suppose it's very likely that an Ethernet cable in buried conduit would get hit. Most likely it's the network device itself, which wouldn't survive a direct hit, with or without upstream protection. The second protector only protects the outdoor device, and only in a very specific circumstance. Did I miss anything?

0
pdoten•

Buried doesn't mean you are protected from surges and the like. At the very least, protect the switch.

2
kam24•

Those look really similar to the ETH-SP from Ubiquiti, which you can get at about $13 a piece.

For more expensive equipment, I like the Polyphaser protectors and put one inside and out.

Any device you choose, make sure it’s properly grounded. They won’t do you any good if they’re not.

3
gusgizmoCCNA•

For lightning protection for outdoor devices:

  1. Shielded cable
  2. Ground everything on one side (the rack side)-- switch, patch panel. Ground items together with a bus bar
  3. Ground bus bar to grounding rod with a dedicated ground wire
  4. Terminate shield on rack side only. Avoid creating a situation where current can continuously flow through the shield (ground loop)
  5. Entrance protector provides extra protection for especially exposed runs, but these should really be fiber anyway

Your main enemy is induced current from nearby strikes. You have 0 chance against a direct hit. Glass becomes a conductor at the voltages involved.

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[deleted]•

[deleted]

4
gusgizmoCCNA•

Exactly!

I don't want to be unhelpful though, so I might recommend that using a fiber patch between the "indoor" and "outdoor" switches is a cheap way to get enough isolation to hopefully avoid replacing literally everything in a branch office when there is a strike nearby. Multi-mode SFP's are like $15 each, and a fiber patch is under $5. Most switches have SFP cages, and if one of yours doesn't you can add a media converter.

3
imjustmatthew•

You have 0 chance against a direct hit.

My understanding from WISP folks is that towers survive direct hits all the time using single point ground systems. It's just a whole bit of engineering in and of itself. The couple of technical manuals I've paged through for giggles actually focus on it more as a propagating broadband RF pulse rather than voltage in the normal sense. It's pretty crazy stuff.

1
pants6000long-time ISPeon•

Fiber is 100% effective at keeping lightning out of your network. Can you run fiber to/near the devices, and use nearby power to run a media converter or small switch w/ SFP port and the device(s)?

2
do_wr_mem•

media converter or small switch w/ SFP port

I think this is the best answer. I would caution to make sure the power is grounded. We've seen lightening travel through the electrical wires and blow the power supplies.

1
Nicosemuta•

To save cost ensure all of your equipment is properly bonded(switches, routers, UPS, PDU ,etc.). TIA 607-B has some solid suggestions. I know Cisco equipment comes with an earthing connector but not with the ground wire to connect to the TMGB. In my years of experience this is always one of the most overlooked yet basic necessities in networking/telecommunications. "Pay me now or pay me later" kind of deals except the pay me later can be quite expensive.

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