Outdoor Telecom Cabinet Fabrication: Street, Pole and 5G Site Cabinets

An outdoor telecom cabinet is an enclosure that has to survive the street for fifteen years while containing equipment that was designed for a room. It will be rained on, baked, frozen, hit, washed by a road sweeper and opened by a technician wearing gloves in poor light. Every one of those conditions is a sheet metal decision.

The Formats That Appear on a Network

The format sets the structural problem. A pad cabinet carries its own weight and the wind load on its faces. A pole cabinet carries almost nothing but must not rotate under wind, because a small misalignment on a pole becomes a large pointing error at the antenna.

Structure and Mounting

• Base and plinth. A pad cabinet needs a level base with a defined fixing pattern, drainage and a cable entry arrangement that stays sealed as the ground settles.
• Pole clamping. The clamp system must resist wind-induced rotation and should not crush the pole coating.
• Lifting and handling points belong on the drawing, because a loaded cabinet is handled with machinery.
• Internal frames should separate the equipment zone from the battery zone rather than sharing one open volume.
• Door hinges must carry a door that may itself hold a heat exchanger, a filter or a second door.

Sealing a Cabinet That Has to Breathe

A sealed cabinet with electronics inside has two problems: heat and pressure. Both are solved in the enclosure design.

• Seal the equipment compartment and cool it through a closed path.
• Use glands, not holes, for every cable entry, and provide a gland plate that can be re-drilled without cutting the cabinet.
• Fit a pressure-equalisation element so that temperature cycles do not draw damp air in through the seals.
• Drain the roof and the base positively, so that water never stands against a gasket.
• Design the door gasket line without interruptions, and put latches where they compress the gasket rather than where they are convenient.

Thermal Design Inside a Street Cabinet

• Closed-loop air-to-air heat exchangers suit sealed cabinets in dusty or wet locations.
• Door-mounted cooling units are common where the load is higher and service access is available.
• Filtered ventilation is the cheapest option and the one most likely to fail on maintenance.
• Solar shading matters more than most designers expect; a light colour with a shaded orientation can remove a significant part of the load.
• Battery temperature should be considered separately, because the acceptable window is narrower than the electronics' window.

RF Interfaces and Non-Metallic Parts

Where radios and antennas are involved, part of the enclosure may have to be invisible to radio.

• Radomes and shrouds for pole-mounted radios are non-metallic, and the metal parts are the internal frame and the mounting interface.
• Antenna mounting brackets are sheet metal and must hold alignment under wind load.
• Cable routing from the radio to the cabinet has a bend radius and a weatherproofing requirement that should be designed, not improvised.
• Earthing of metal near an antenna has to be agreed with the RF designer, because a large metal surface in the wrong place changes the pattern.

Power, Battery and Earthing Compartments

• Provide a separate power zone with its own barriers, shielded from the electronics zone where the specification requires it.
• Design the battery compartment for the battery mass, not for the cabinet volume.
• Provide ventilation where the battery chemistry requires it, and route it so it cannot draw water.
• Give the earthing bar a defined position, size and material, and bond doors, panels and the shroud frame to it.
• Keep the lightning protection interface on the drawing, because a street cabinet is often the tallest metal object in its immediate area.

Security, Access and Vandalism

• Use security fasteners on all externally accessible fixings, and keep the door hardware simple enough for a technician in gloves.
• Provide a door stay so the door does not swing into traffic or damage the gasket.
• Recess the lock and the hinges where they cannot be levered.
• Label the cabinet with the operator's identification, in a way that survives cleaning and sunlight.

Coatings for a Street Environment

The cut edges and the holes are where a coated cabinet starts to corrode, so the coating specification should say how they are protected as well as how thick the film is.

First-Article and Site Checks

Our Approach to Telecom Cabinets

• We fabricate cabinet bodies, doors, roofs, base frames, gland plates, battery compartments and mounting brackets in steel, aluminium and stainless.
• We build the sealing and drainage features into the construction and dimension the gland plate and entry positions from the site drawing.
• We will say when a requested thermal strategy and a requested IP rating cannot both be met in the proposed construction.
• We do not supply the radios, antennas, batteries, cooling units or lightning protection devices, and we do not certify the RF or electrical design of the site.
• Every quotation states which operations are completed in our plant.

Send the site conditions, the equipment layout and the mounting arrangement, and the cabinet can be designed for the place it will actually stand.

Frequently Asked Questions