Match it to the actual exposure - and remember the connectors and glands are usually the weak point rather than the enclosure.

A rating that resists driving rain covers most exposed positions. Higher ratings intended for jetting or immersion belong where washing down happens or where flooding is credible.

The enclosure is rarely what fails. Water enters at the Ethernet gland, at an antenna connector that was not weatherproofed, or through the cable itself by capillary action when the cable runs downward into the unit.

So the installation practice counts for as much as the rating: use the supplied glands correctly, weatherproof antenna connections with the proper tape system, and form a drip loop so water runs off the cable before it reaches the enclosure.

Coastal and industrial sites add corrosion. Salt attacks connectors, fixings and enclosure seals, and stainless mounting hardware plus regular inspection is what turns a five-year installation into a fifteen-year one.

Surge arrestors at both ends of the cable run, a properly bonded earth, and - where it can be justified - fibre with local power to remove the conductive path entirely.

A direct strike is rare. What is common is a nearby strike inducing a large transient into a long copper run, particularly one that goes up a mast or across a roof.

The energy travels down the Ethernet cable into the building, and the casualty is frequently the switch port - or the whole switch - rather than the access point outside.

Surge arrestors fitted at the outdoor unit and again where the cable enters the building divert that energy to earth. They only work if the earth is real and properly bonded to the building's earthing system; an arrestor connected to a painted bracket does nothing.

For high-exposure positions - tall masts, exposed sites, buildings with a history of strikes - a fibre uplink with local power is the definitive answer, because glass conducts nothing.

Arrestors are consumable and should be inspected and replaced after events.

Integrated for general area coverage, external where the coverage needs to be shaped or the distance is significant.

Integrated antennas are simpler, weatherproof by design, and give a broad pattern suitable for covering a yard, a car park or a seating area. There is nothing to specify, align or weatherproof.

External antennas allow the pattern to be chosen. A sector antenna covers a defined arc from the corner of a site; a directional antenna concentrates energy along a corridor or towards a distant building; a downtilt pattern covers a yard from a high mast without wasting energy on the horizon.

The cost is complexity: connectors to weatherproof, cable losses to account for, and alignment to get right - and all the antennas must be connected, since multiple-input systems perform poorly with one missing.

As a rule, if the area is roughly circular around the mounting point, integrated is right. If the shape is anything else, external antennas are what make it efficient.

PoE where the cable run allows it, with attention to loss over distance; local power with a fibre uplink where the run is too long or the exposure too high.

PoE is the usual answer: one cable for power and data, no supply needed at the mounting point, and remote power cycling from the switch.

The constraint is the 100 m limit and the voltage drop over it. An outdoor unit with heaters at the far end of a long run may be below its required class, and the symptom is a device that reboots in cold weather - which is exactly when it is hardest to investigate.

Where the distance exceeds the limit, the options are a fibre run with a local PoE injector at the far end, an Ethernet extender, or local mains power.

Fibre plus local power is also the right answer where surge exposure is high.

Whatever is chosen, put the source on protected power. Outdoor units are usually the ones covering the areas that matter during an incident.

The enclosure's internal range, which in sun is well above ambient and after a winter outage is well below - and check the start-up figure separately.

An enclosure in direct sun can reach far above the shade temperature, particularly a dark one with no airflow. Specifying against the local maximum air temperature is not sufficient.

At the cold end, the important figure is often start-up rather than operating. A unit running continuously generates its own heat; one that has been off overnight in winter has to boot from ambient, and some equipment specifies a narrower range for that.

Solar shields help substantially at the hot end and cost little. Heaters exist for the cold end, and they change the power requirement significantly.

Also consider condensation. Repeated warming and cooling moves moist air in and out of an enclosure, and water accumulates inside a perfectly sealed housing over time - which is why breather vents exist and why 'sealed' is not always the correct specification.

On a fixing rated for the wind load with the antenna fitted, with access for maintenance considered before installation.

Wind loading is the structural case, and an access point with a large external antenna presents far more area than the unit alone. Pole and wall fixings must be rated accordingly, and lightweight brackets that are adequate indoors are not.

Height is a trade-off. Higher gives better line of sight and keeps the unit out of reach; it also makes maintenance a working-at-height task, and puts the unit into a worse position for lightning.

Think about access before installing. A unit that requires a tower or a road closure to reach will not be maintained, and its first fault becomes a project.

Allow for cable management and drip loops, secure any slack against wind, and use ultraviolet-stable ties - ordinary cable ties become brittle and fail within a couple of years outdoors, which is a surprisingly common cause of hanging cables.

Periodic inspection of seals, connectors, fixings and surge protection - and cleaning where the environment deposits anything.

Check cable glands and antenna connections for water ingress, which usually shows as corrosion at the connector before it shows as a fault. Look at the weatherproofing tape system; it degrades in ultraviolet and needs renewing.

Inspect mounting hardware for corrosion and for movement. A bracket that has loosened will eventually change the antenna's aim, which on a directional installation degrades the link progressively.

Surge arrestors should be checked and replaced after significant electrical storms - they are sacrificial and a spent arrestor offers no protection while looking identical to a good one.

Cleaning matters in dusty, salty and agricultural environments, where deposits both retain moisture and accelerate corrosion.

Trend the wireless statistics as well. A slow decline in signal quality on a fixed installation usually means an antenna, a connector or an alignment problem rather than a radio fault.