I need to link a network switch from an outdoor location to a main rack. The only cabling currently in place is cat5e with 3 bad pairs (i.e. the pairs are shorted) and RG59. Run length is approx 150'. There is an outdoor weather box at the switch location, but there is no power. (The network switch is being powered over 18/2 that runs back to the house.)

The network switch has two 8MP cameras and an 802.11ac WAP connected to it. WAP performance need not be excellent (i.e. 80 to 100Mbs is fine.)

Currently, the switch is uplinked to the main network using a temporary cat6 that we ran across the property.

What I need is a permanent solution, and running new cable would be tricky, as it's a takeover job and I have not been able to reverse engineer the conduit situation.

So, what is my best option to create a highly reliable 100-200Mbs network link using the available wiring? Again, one end of the link is outdoors and has no power. And, available wiring is one pair within a cat5e cable plus an RG59.

To power 2 8mp IP cameras, 1 ac WAP, and a POE switch - an 18/2 power wire at 150 feet, is pushing the limits. If you can NOT run any new wires, the ONLY option is to use a wireless point-to-point. But now you are adding another powered device on an 18/2 that is already pushing the limits.
In your other post about 125' of 18/2 with a POE switch, that would have just been enough. But at 150' and this many power hungry devices.... No!

Listen. You NEED to pull proper replacement wiring. If you try to rig this janky BS up, there is a high probability of having issues. Don't do it.

When running new wire, I would have an electrician trench an electrical conduit of his own, to the outside building for power. Having power out at the building will do a lot for the customer; not just for your system but other things as well (lights, outlets, etc.).

And lastly, pull fiber with the new wiring.
If you have to run low voltage power (no electrician and a stupid low budget), then run a 16/4 (or even better 14/4 if you have it) so you will have enough choices to power everything properly in that box (assuming the box is big enough for all the black boxes and switch).

At this point I would assume that there are really 3.759 bad pairs and I wouldn't even trust the cable for being a reliable pull.

I agree that running new wire is the best plan.

If installation cost is the issue, maybe Arlo is an option. I came across this a couple days ago, having been installed by the GC. I made sure that the WiFi was working, but ignored the Arlo. The GC and customer can struggle with this if they like. I have no idea how long the the battery run time might be. I suspect that the 150 feet might present an issue, but have no proof. But, if WiFi interference levels are low, Arlo might have a chance.

I was very uneasy at first about powering the switch over 150’ of 18/2. However, after beating up on this setup, I’m almost at the point where I think it’s a non issue.

In parallel to this thread, I am exploring the logistics of running new cable. And, I agree that the one remaining “good” pair on the cat5 should not be relied on.

But, if there is a bulletproof Ethernet over coax solution I can use in this application, I’m open to giving it a try.

[Link: doorbird.com]

We've had success with these in situations like yours. The 18/2 could do it if its start point can somehow get a data connection.

Or, as crazy as it sounds, we've used it on shorted cat cables as well. For example, if the shorts are somehow isolated (i.e blue and blue/white are shorted to each other but nothing else as are the orange and the orange/white.) The blue shorted wires and the orange shorted wires together make up the two wires for the doorbird POE. I know it sounds nuts, but it has worked for over a year. Customer was willing to take the risk of short term success.

That is a classic symptom of a CAT wire that was pulled WAY to hard. The wires when stretched will start to cut into each other.

I once came across a job where an electrician was tasked with pulling 2 Cat5e cables thru over 600' of conduit. It had a large nylon pull string in it. When they couldn't pull the cable thru with the strength of themselves, they got the bright idea of hooking the pull cable up to a truck and pulling it thru. They got the cable thru and almost every wire was shorted together.
When I arrived to look at what wiring they had to control the gate system, I was told the story. Electrician with a straight face said "we must have got some defective wire". Needless to say I loudly explained exactly what happened and what f^n idiots they were. They got very pissed with me but come on!!! How stupid have you got to be!

All 6 wires seem "lightly" shorted. (I didn't test them with a meter, but the continuity light faintly glows.)

The one good pair was being used for RS485 communication to the prior camera. My guess is that there is a splice somewhere where the unused pairs were separated from the used pair and not properly weather protected.

Still working on the option of pulling new cable. This thread on tracing buried cables may prove helpful:

[Link: remotecentral.com]

Look at it this way- if POE works over Cat5e cable that's only 24 gauge, 18/2 has four times the cross-sectional area, so it will handle a lot more current which is less important than reducing voltage drop and maintaining voltage is something you need.

Maybe you could connect a TDR and find where the issue lies.

I've used one of these successfully, but it was only one camera on the far side.
[Link: blackwiredesigns.com]

Mobotix MX2Wire. Really handy device.

Unifi Nano Beam

The conduit was installed for mechanical protection, and for running new cables. I would try to use the existing conduit. Maybe add a pull box.

But, running new conduit may be cheaper. Running new conduit, with power, is better in the long run, and has a much more predictable cost, with someone else doing the work.