Faced with several remote solar and wind inverters which have data boxes on them, which are network connected. Right now I have a switch and all the boxes go to the switch, and then via a CAT 5e cable to my managed switch in the basement.

I would prefer, for two reasons, running individual cables to each data box. First, it eliminates a switch which burns about 7 watts. The second reason is that it allows me to isolate the data boxes, which I sometimes have to reconfigure (like for different static IPs, etc.) If I run separate wires to the managed switch, then I can pull the perspective cable, and plug it into a laptop or whatever for maintenance, without running out in the cold, climbing up a ladder with a laptop, etc.

I am also running low on CAT 5e cable, but have about 1500 feet of CAT 3 cable.

To use what I have, and avoid running several longer (<150ft) runs of CAT 5e, I am considering running CAT 3.

Looking around, the Wiki lists CAT 3 as being approved for 10 Mbps, and my managed switch will run at 10 Mbps. Therefore there is substantial temptation to have the low data rate line be run with Cat 3 wire.

Does anyone have any similar experience? Anything else to add?

Obligatory Linux content: this also helps me isolate the communications so that I can reverse engineer the queries of the data box.

You already know the limitation of cat3, so if all the adapters support 10 mb, yeah, it'll work just fine.

You can run all sorts of cable if you nic's don mind. Some do. Some can be set at slowest speeds.

Easy enough to test. Take the entire cable and put ends on it. Then use it between two nic's and see what it does.