Comms Room Design for a Small Business

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.

1. 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.
2. 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.
3. Add headroom. Running a UPS at the top of its rating shortens battery life and leaves nothing for a future addition.
4. 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.
5. 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.
6. 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.
7. 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.

The most expensive mistakes in an office fit-out are made before anyone thinks about IT. Cable routes that were never allowed for, a comms cupboard with no power and no air, and a carrier order placed after the lease was signed instead of before. Two of those three cost you plasterboard to fix. The third costs you an office you cannot trade from.

Fit-out IT is the permanent technology infrastructure built into a tenancy while it is under construction: the structured cabling, the pathways it runs in, the comms room, the access point and camera positions, the floor boxes, and the carrier service that feeds all of it. It is defined by the fact that most of it becomes inaccessible once the building is finished.

This is written for the operations manager running the project, sequenced against the build programme rather than grouped by technology. Work through it in order.

Stage 1: before the builder starts

These are design decisions. Every one of them is cheap now and expensive later.

Order the carrier service. This is the single most common cause of a business moving into a new office with no internet, and it is entirely avoidable. A new service at a new address is not a phone call, it is an order with a build behind it. nbn is explicit that for Enterprise Ethernet it designs and builds a new fibre connection tailored to the premises, that installation is handled by specialist project teams for complex environments like shopping centres, business parks and high-rise buildings, and that a committed delivery date is confirmed with your service provider. Civil works may be involved.

nbn does not publish a delivery target in business days, and that is the useful finding. There is no customer-facing figure at all. The only delivery number anywhere in nbn’s published material sits in the wholesale agreement, in the Service Levels Schedule for the nbn Enterprise Ethernet product module, and it is not what people assume: nbn aims to provide a Committed Delivery Date within 10 business days of the Order Accepted Notification, and that target is expressly stated to be non-binding, aspirational, and not even reported to the retail service provider. Ten business days to be told a date, not ten business days to get a service.

What does bind is the Committed Delivery Date itself, once given. If nbn delivers late against it, rebates accrue to your retail service provider: for an Ordered Product with a Committed Delivery Date on or after 15 November 2021, 100 per cent of the monthly recurring charge whether delivery is 5 to 9 business days late or 10 business days or more late. Read that carefully. The rebate is payable to your provider, not to you, and it does not compensate you for a building you cannot trade from.

The practical consequence for a fit-out programme is that your carrier lead time is a retail service provider commitment, not an nbn published standard, and it will vary by address, by building complexity and by whether a build is required. Do not plan against a number you found on a comparison site. Make the retailer put the Committed Delivery Date in writing, along with what happens contractually if it slips, and treat the date before you have that as unknown.

Place the order the week the lease is signed, not the week before handover. If the build timeline will not make your move date, you need to know early enough to arrange an interim service. This is the point at which you should be ordering the carrier service first and building the rest of the programme around it.

Fix the comms room location on the drawings. Not “somewhere near the back”. A specific room, with a door, a dedicated power circuit and a way for heat to leave. Get it onto the architectural set before the layout is frozen, because moving it later moves every cable in the building. There is a full treatment of how to design the comms room itself, and it should be read at this stage, not at fitout.

Set the headcount you are cabling for. Not today’s headcount. The headcount at the end of the lease, plus the desks you will add when you take the adjacent tenancy. Outlets are cheap while the walls are open and brutal afterwards.

Specify the cabling grade above current need. Structured cabling for commercial premises in Australia and New Zealand is covered by AS/NZS 11801.1:2019, which is the local adoption of the ISO/IEC 11801 series and replaces the older AS/NZS 3080. The grade you choose sets the ceiling on everything for the life of the fit-out.

The reasoning is simple. Active equipment gets replaced every four to six years. Cable in a wall gets replaced when you next renovate, which might be never. Wireless access points and cameras increasingly draw more power over the same cable, and higher Power over Ethernet classes generate more heat in the bundle. Specify the higher category, specify shielded where you are running near plant or lift motors, and accept the extra cost now.

Decide the access point positions from a plan. Not by counting rooms. Wireless design starts from the floor plan, the wall construction, the ceiling type and where people will actually sit, and it produces marked positions with a cable to each one. There is a fuller treatment of designing wireless coverage from a plan which applies just as much to an office as a warehouse. Add a spare cable to every position and one or two more positions than the design calls for, because a plasterboard ceiling is a one-time opportunity.

Decide what else rides on the network. Access control readers, door controllers, cameras, intercoms, room booking panels, digital signage, EFTPOS. Each of these needs a cable and most need PoE. Work out CCTV and access control on the same network now, because a door controller discovered at fitout is a cable that has to be surface mounted.

Stage 2: before plasterboard goes up

This is the expensive one. Once the sheets are on, everything below costs you a repair, a repaint and a delay.

First fix the cabling. Every outlet, every access point, every camera, every door, every meeting room, every floor box, run back to the comms room. Overshoot on quantity. A spare outlet costs a fraction of a retrofit.

Get the separation from power right. Telecommunications cabling in Australia is governed by AS/CA S009:2020 Installation requirements for customer cabling, the Wiring Rules published by the Australian Telecommunications Alliance. The ACMA makes it mandatory through the Telecommunications Cabling Provider Rules 2014. Among other things it sets out that telecommunications cabling must be separated from electrical cabling. This is not a best-practice suggestion. It is a compliance requirement, and it is enforced through registered cabler obligations.

Practically, this means the electrical contractor and the cabling contractor need to agree routes before either starts, and that the separation applies in trays, in conduits, in risers and at the outlet. Data and power sharing a stud cavity because it was convenient on the day is how a fit-out fails its own certification.

Pathways and spaces. AS/NZS 3084:2017 covers telecommunications pathways and spaces for commercial buildings. This is the standard that governs cable tray, risers, conduits, ceiling routes and the equipment room itself. Ask the cabling contractor to reference it in their scope. If they cannot, that tells you something.

Conduits for door hardware and access control. Every controlled door needs a path from the door frame to the controller and from the controller to the comms room. Electric strikes, maglocks, readers, request-to-exit sensors and door position switches all need cable. Doors are usually the last thing decided and the first thing that cannot be retrofitted neatly, because the conduit has to be in the frame.

Floor boxes and desk power. Fix the desk layout before the slab penetrations and the floor box positions are set. Every floor box needs both power and data, sized for the desk pod it serves and for one more person at that pod than the layout shows. Under-floor and in-slab routes are permanent, so get the count right.

Meeting rooms. Every meeting room needs at least a cabled connection to the display position, a cabled connection to the camera and speaker position, power at both, and a route between them that does not cross the room at head height. Decide the mounting height of the display now, because the outlet has to be behind it.

Comms room backing and containment. Plywood backing boards, cable entry points, tray into the room, and the floor space for the rack marked out and protected. If a rack is going in, the door and the route to it need to fit the rack.

Take photographs. Before the sheets go on, photograph every wall with cable in it, with a tape measure in shot. This is the cheapest as-built documentation you will ever produce and you will use it within two years.

Stage 3: at fitout

Second fix. Terminate the outlets, fit the plates, mount the access points, hang the cameras, terminate the patch panels.

Build the rack. Patch panels at the top, switches beneath them, room for growth, cable management between every panel and switch, and the carrier equipment positioned to the carrier’s own requirements. nbn’s BNTD location guide is worth reading before the rack is laid out. For a rack-mounted Enterprise Ethernet install it specifies a minimum rack depth of 300mm for the tray, a mandatory 1RU clearance for cooling the BNTD, a minimum 26mm clearance at the cooling vents, a recommended minimum front clearance of 900mm, a 240V general power outlet or IEC C13 PDU within 1m, a maximum mounting height of 2.4m with below 1.8m preferred, and a communications earth or rack earth. Space reserved for the carrier must stay reserved.

Label as you go. Administration of communications cabling systems is covered by AS/NZS 3085.1:2004. A labelling scheme decided at handover is a labelling scheme that never gets applied. Decide it before termination and apply it at both ends.

Power the room properly. Dedicated circuits, enough outlets, and the UPS in place before equipment goes in rather than added afterwards.

Stage 4: at handover

This is where you find out whether you got what you paid for.

Certification testing, not a link light. Every cable run must be tested against the performance class it was specified to, with a calibrated field tester, and the results supplied as a report per outlet. A cable that carries traffic today is not the same as a cable that passes certification. The difference shows up at higher speeds and higher PoE loads, sometimes years later.

The cabler’s statement of compliance. Under the Telecommunications Cabling Provider Rules 2014, after finishing a job a registered cabler must prepare a written statement certifying that the work complies with the Wiring Rules, give a copy to the customer who commissioned the work, give a copy to their employer or contractor, and keep a copy. You are the customer. Ask for it. If nobody can produce it, the work was not done by a registered cabler or the paperwork was skipped, and either way you have a problem to solve now rather than at the next audit.

As-built documentation. Floor plan with every outlet numbered, patch schedule, rack elevation, access point positions with names, camera and door positions, carrier service details with the service ID, and the photographs from stage two. This should be handed over as a set, not reconstructed later by whoever inherits the site.

Warranty and defects. Get the cabling warranty terms in writing and note the defects liability period. Walk the site with the cabling contractor and list anything unterminated, unlabelled, unfixed or untested before you sign off.

A functional test of the things that are not cables. Every meeting room display, every access point at the far corners with an actual device, every door, every camera view, the phone system at every desk, and a full failover test of the internet service if you have a second link.

The two failures worth naming

Almost every fit-out that goes badly fails in one of two ways.

The first is the carrier service. Everything else in this list can be recovered with money and a weekend. A fibre build that has not started cannot be accelerated by shouting at anyone. Order it first.

The second is the comms room. It gets allocated to whatever space nobody else wanted, which is usually a cupboard with one power point and no ventilation, and within eighteen months it is the hottest and least accessible room in the building. Design it deliberately.

If your fit-out is also a relocation, the move itself is a separate piece of work with its own sequence, and the cabling side of it is covered in professional data cabling.

Send us the floor plan and the build programme and we will mark up the IT scope against your milestones, including the date the carrier order has to be placed. TechAssist does cabling, comms rooms and fit-out IT in-house rather than subcontracting it. Call 1300 028 324 or use https://techassist.au/contact/.