Most small business comms rooms fail within two years for the same reason: nobody chose the room, the room was left over. A comms room is the space that houses your network rack, your patch panels, your carrier equipment and your UPS, and everything in your business that touches the internet or the network passes through it. Treat it as a room with a design brief, not a cupboard with a door.
Here is what to get right, and why the usual shortcuts stop working around the eighteen month mark.
Why they fail
Three failure modes, in order of frequency.
Heat. Every watt that goes into the rack comes out as heat. A sealed cupboard with no air path reaches equilibrium at a temperature well above what the equipment is rated for, and the result is not a dramatic failure, it is switches that reboot occasionally, drives that die early and a UPS whose batteries age at several times their rated rate. Nobody connects the symptom to the room.
Growth. The rack was sized for the equipment on day one. Then came a second switch, a firewall, a NAS, the carrier’s equipment, a patch panel for the extra desks and a UPS. There is now no vertical space, no depth and nowhere to route the cables, so equipment sits on shelves and cables run diagonally.
Discipline. The first patch was neat. The two hundredth was not. Without a labelling scheme and a rule that every change gets documented, a comms room degrades into something nobody will touch, which means changes get made badly because tracing the correct cable takes too long.
All three are design problems, and all three are cheap to prevent.
Siting: where it must not go
Not the kitchen or a kitchen cupboard. Water, steam, heat from appliances and food traffic.
Not under the stairs. It is a heat trap, it usually has no dedicated circuit, and the headroom means you cannot get a ladder or a person behind the rack.
Not against a west-facing external wall or anywhere with direct sun. Solar gain on a wall is significant and it peaks at the same time as the afternoon load.
Not the store room that will later hold stock, cleaning chemicals or the Christmas decorations. Shared rooms fill up, and equipment ends up boxed in.
Not near the plant room, lift motor room, or the main switchboard if you can avoid it, because of electrical noise and heat.
What you want instead is an internal room or a dedicated cupboard with a solid door, no water services above or adjacent, a way for air to move, a dedicated power circuit, room to open the rack front and rear, and a lock. AS/NZS 3084:2017 covers telecommunications pathways and spaces for commercial buildings and is the standard your cabling contractor should be designing the space against.
Central is better than convenient. Cable runs are limited in length, and a comms room in one corner of the floor plate means longer runs and, on larger floors, a second room.
Rack sizing and depth
Two dimensions and both are usually got wrong.
Height, measured in rack units. Count everything going in: patch panels, cable management bars between them, switches, firewall, carrier equipment, UPS, any server or NAS, and a power distribution unit. Then add the growth. A rack that is full on the day it is commissioned is a rack that will have equipment sitting on a shelf within a year. Vertical space is the cheapest thing in the room.
Depth. This is the one that catches people out. Wall-mounted cabinets are often too shallow for anything with a real chassis, and once you add patch leads at the front and power leads at the rear, the door will not close. Depth also determines whether air can move around the equipment. As a concrete example of how specific carrier requirements get, nbn’s Enterprise Ethernet BNTD location guide specifies a minimum rack depth of 300mm for the equipment tray, a mandatory 1RU clearance for cooling, a minimum 26mm clearance at the cooling vents, and a recommended minimum 900mm clearance at the front of the rack for installation and maintenance access. If your rack is jammed against a wall in a corridor, the carrier’s installer may simply refuse the job.
Access. Front and rear access is the difference between a ten minute change and a two hour one. A floor-standing rack you can walk behind beats a wall cabinet you have to unscrew, every time. If a wall cabinet is genuinely the only option, get a swing-frame type so the body hinges away from the wall.
Mounting height. The nbn guide caps equipment height at 2.4m and prefers below 1.8m, with a minimum clearance from the ground. That is a reasonable rule for everything in the room, not just carrier gear. Anything you cannot reach without a ladder will be maintained badly.
Power and dedicated circuits
The comms room needs its own circuits, not a spur off the office ring that the cleaner’s vacuum also lives on.
Specify at least one dedicated circuit for the rack, sized for the full load with headroom, and have your electrician design it under AS/NZS 3000. Two circuits from separate breakers is better if you have dual-corded equipment. Put the outlets where the rack is, not across the room, and use a rack-mounted power distribution unit rather than a power board on the floor.
You also need a communications earth or rack earth. This is standard practice and, for carrier equipment, it is a stated requirement.
One more thing that costs nothing: label the breaker in the switchboard, clearly, and label the outlets in the room. The number of outages caused by someone turning off the wrong circuit during unrelated works is not small.
UPS sizing: the method, not a number
Do not buy a UPS by guessing. Work through this sequence.
- Inventory the actual load. Every device going in the rack, at its real draw, not its nameplate maximum. Nameplate ratings are worst case and buying to them wastes money.
- Add the growth. Whatever you are going to add over the life of the unit, plus PoE budget if your switches power access points, cameras and phones, because PoE load is real load.
- Add headroom. Running a UPS at the top of its rating shortens battery life and leaves nothing for a future addition.
- Convert correctly. UPS capacity is quoted in volt-amps and in watts, and they are not the same number. Size against the watts figure for your real load, and check the power factor rather than assuming.
- Decide what runtime is for. There are two different answers and they lead to very different units. If the UPS exists to ride through brief interruptions and to shut equipment down gracefully, you need enough runtime for an orderly shutdown plus a margin. If it exists to keep the business trading through a longer outage, you need a much larger unit, or a generator, and you should say so out loud because the cost difference is substantial.
- Plan for the batteries. UPS batteries are consumables. Decide now who monitors their health, who gets alerted, and what the replacement interval is. A UPS with dead batteries is a very expensive power board, and heat in a badly ventilated room shortens battery life considerably.
- Test it. An untested UPS is an assumption. Test under load, on a schedule, and record the result.
Set the runtime target against your actual recovery requirement rather than a number that sounds reassuring. There is more detail on UPS and power protection if you want to go deeper on the equipment side.
Ventilation and heat load
The physics is simple. Almost all electrical power drawn by IT equipment is converted to heat, so the heat you have to remove is close to the power you put in. Add the UPS, which produces heat of its own.
Work out the total load in watts, treat that as the heat you need to shift, and then decide how it leaves the room.
Passive means vented door, vented cupboard, air path in at low level and out at high level, and a room that is part of the building’s conditioned volume. This works for genuinely small loads in a room with a decent air path. It stops working the moment you add a server.
Active means a dedicated split system or a supply and return into the room from the building system, sized for the heat load and not for the floor area. A room-sized calculation will undersize it every time, because the load per square metre in a comms room is nothing like an office.
Two rules. The room’s cooling must not depend on the building air conditioning being on, because building systems run to office hours and your equipment does not. And someone must be alerted when the room gets hot, which means a temperature sensor with alerting, not someone noticing on a Monday.
Also keep the rack airflow front to back. Blanking panels in unused rack units cost almost nothing and stop hot exhaust air recirculating to the front of the equipment.
Cable management and patching discipline
The rule is one cable, one path, one length.
Patch leads should be the correct length for the run, not a 3m lead coiled behind a 200mm connection. Horizontal cable management bars between every patch panel and switch. Vertical management down at least one side. Fixed cabling terminated onto patch panels, never directly into switches, because a patch panel is what lets you change equipment without re-terminating.
Keep power and data separated in the rack as well as in the walls. AS/CA S009:2020 requires separation between telecommunications cabling and electrical cabling, and it applies inside the cabinet, not only in the building fabric.
The discipline part matters more than the hardware. Set a rule that no temporary patch survives the day it was made, and that every change is recorded. A comms room degrades one shortcut at a time.
Labelling
Administration of communications cabling systems is covered by AS/NZS 3085.1:2004. Decide the scheme before termination and apply it consistently.
At minimum: every outlet labelled at the wall plate and at the patch panel with the same identifier; every patch panel labelled; every switch and port range labelled; every circuit and PDU labelled; carrier services labelled with the service ID so a fault call does not start with ten minutes of searching.
Labels must be machine printed and permanent. A handwritten label on masking tape is a label with a one year lifespan.
Physical security and access
The comms room holds the network. Anyone with physical access to it has physical access to everything on the network, and physical access defeats most software controls.
Lock it, and control the key. If you have access control on the building, put the comms room on it so you get an access log. Do not put it on the general cleaner’s key. Do not leave the key in the door because the cleaner needs to get to the mop sink, which is another reason not to share the room.
Fit a door contact so you know when it has been opened outside hours, and put a camera on the door rather than inside the room. Keep a visitor rule: contractors are escorted, and their work is recorded.
Smoke detection in the room should be on the building system. Do not put a sprinkler head directly over the rack if you have any say in it, and do not store anything flammable in there.
What good looks like at handover
Ask for all of this before you sign off. If the contractor cannot produce it, the job is not finished.
- Certification test results for every cable run, per outlet, from a calibrated tester, against the specified performance class.
- The registered cabler’s written statement certifying compliance with the Wiring Rules, which the Telecommunications Cabling Provider Rules 2014 require them to give you as the customer who commissioned the work.
- A rack elevation drawing showing what is in every rack unit.
- A patch schedule mapping every outlet to a panel port to a switch port.
- Floor plan with outlet numbers matching the labels physically applied.
- Carrier service details, service IDs and the fault reporting number.
- Photographs of the front and rear of the rack at handover, so future changes can be compared against a known good state.
- Confirmed power circuits, breaker labels and earth.
- UPS model, load at handover, calculated runtime and battery replacement date.
- A temperature reading in the room under normal load, taken with the door closed.
That last one is worth insisting on. A room that is already warm at handover, with the lowest load it will ever carry, is a room that will be a problem by the second summer.
Where this fits in the bigger job
If the comms room is part of a new tenancy, it needs to be on the drawings before the layout is frozen, which is covered in the fit-out checklist. The cabling that terminates in it is covered in professional data cabling and structured cabling, and the choice of the switches and gear that go in it is a separate decision that follows the room, not the other way around. If you already have a comms room and you are not sure how bad it is, audit what you already have first.
If your rack is in a cupboard and you are not sure whether it is a problem yet, take a photograph of the front and the back, and a temperature reading with the door shut, and send them to us. TechAssist builds comms rooms in-house across Melbourne’s outer east and greater Melbourne. Call 1300 028 324 or use https://techassist.au/contact/ to book a site visit.