Ungrounded outdoor Wifi access point - bad idea?
April 21, 2021 2:19 PM   Subscribe

I am planning to install a wireless access point for my backyard, mounted to the exterior wall of the house, powered via PoE. I know that the right way to do this is to run shielded cable from the AP to a grounded Ethernet surge protector followed by unshielded cable to the rest of the network. But given that the cable run is a total of maybe 20 feet of which 4 are outdoors, and that the AP is mounted maybe 2 feet above ground level, how bad would it be for me to do it the wrong way?

To be clear, the wrong way is to run unshielded Cat6 from the PoE injector through the wall to the access point, carrying maybe 15W of DC. I am fine risking my AP and PoE injector, but I don't want to start a fire or endanger the other equipment on my network.

I am hoping someone who works with outdoor Ethernet cabling regularly can rate this on a scale from "professionals do this all the time" to "this is suicidal". Thanks!
posted by goingonit to Computers & Internet (7 answers total)
I know nothing about electricity (except I always got it backwards) or wiring, and this answer doesn't really address your question, but what is preventing you from putting an access point next to a back window of your house? The signal won't be as strong, but we still get a solid signal about 15 to 20 yards from our upstairs window to the back yard.
posted by JawnBigboote at 2:31 PM on April 21, 2021

I am not a licensed electrician (or even an unlicensed one, really), but I don't see anything horribly wrong with just running the cat5/6 through the wall and plugging it in to your AP.

I have two APs (one in the front yard, one in the back yard) hooked up more-or-less in this way and nothing has gone wrong yet.
posted by Juffo-Wup at 4:05 PM on April 21, 2021

Best answer: The company I work for has installed maybe 30 or 40 outdoor APs at commercial sites over the last few years. We don't bother with shielded cable or ethernet surge protectors, and none of those sites have burned to the ground yet.

FWIW we use Ubiquiti APs and regular ol' cat6 riser cable. Usually the way we do stuff, the bulk pulled cable doesn't even go outside. We just run it to the location on the inside of where the AP will be, terminate it, penetrate the wall and run a (unshielded) patch cable to the AP, then seal up the penetration with caulk or silicone etc.

Your right way sounds super great! Also, professionals don't do that all the time.
posted by glonous keming at 4:29 PM on April 21, 2021 [1 favorite]

Response by poster: Thanks glonous keming that's exactly what I wanted to know!
posted by goingonit at 8:16 PM on April 21, 2021

The voltage inside a PoE cable is never higher than 48VDC and the power injectors are all current limited, so the motivation for shielding isn't to protect your house from the Terrible Secret Of PoE, it's to limit electromagnetic interference radiated by the cable and protect stuff connected via the cable from induced currents caused by nearby lightning strikes.

given that the cable run is a total of maybe 20 feet of which 4 are outdoors

The size of a lightning-induced current depends a lot more on the length for which a cable is distant from the ground than whether it's actually outside the building envelope or not. With the cable run you describe, I don't think your chances of lightning-induced equipment damage would be any different whether your AP was inside or outside your wall.
posted by flabdablet at 11:35 PM on April 21, 2021 [1 favorite]

Also, the PoE output is isolated from the input by a flyback DC-DC converter. There is a transformer in between that eliminates a direct wire connection. There is no ground connection between input and output. Both data and power are galvanically isolated.
posted by JackFlash at 7:54 AM on April 22, 2021 [1 favorite]

Response by poster: And it's done. Ran an unshielded patch cable through the wall and terminated it at a female-to-female wall jack, everything works and looks great. Thanks everyone for the help!
posted by goingonit at 1:13 PM on April 23, 2021 [1 favorite]

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