Switches in mild outdoor environments
If the switch won’t be rained on, almost any NEMA box with a fan or at least a vent will do for the typical PoE switch.
Switches in hostile environments
A site like a sawmill is the harder case. A fan there will clog with fine sawdust quickly and stop turning. Putting a filter in front of the fan only shifts the problem: the filter clogs instead, and you end up with a hermetically sealed box around a switch — at which point heat is the killer.
The pattern that works in dusty environments:
- Pick a sealed enclosure. No fan, no vent.
- Pick a metal enclosure, not plastic — the metal walls conduct heat out to the surrounding air.
- Size it well above the switch. Use a box noticeably larger than the switch itself so air can circulate inside and move heat to the walls.
Either of these works in practice:
- VEVOR NEMA 4X Steel Enclosure, 20 × 16 × 10″, IP66
- Yuco YC-20X20X8-IP65-FE, NEMA 4 / IP65, 20 × 20 × 8″
Any IP5x or IP6x rating is fine. (IP65, for example,
means fully dust-tight — the 6 — and protected against water
jets — the 5.) Larger is better; mount the switch to the
backplate with clearance on every side so air can circulate over
the top and sides.
Wi-Fi APs
The thermal story is much easier for APs because they only dissipate about 5–7 watts at typical load. Standard ABS or polycarbonate outdoor enclosures work fine. Don’t use metal — it’ll attenuate the radio.
One that’s been lab-tested outdoors at a farm in Oregon: