Commercial fit-out electrical: what to lock in before the builder starts.

What the base-build landlord provides, and what it doesn't

Almost every tenancy dispute in commercial fit-out comes back to a misunderstanding about what the base-build provides. The landlord's base-build electrical provision is typically:

• A metered supply point to the tenancy (usually a sub-board or isolator inside the tenancy space, sometimes just a connection point in the main switchboard)
• Basic common area lighting and power (corridor, lobby, toilets if shared)
• Potentially a base level of power and lighting within the tenancy shell, but often not

What the base-build almost never provides adequately:

• Enough circuits for a functioning fit-out
• Appropriate sub-board capacity for the tenant's intended use
• Any data or communications cabling
• Dedicated circuits for kitchen or catering equipment
• Power for mechanical and HVAC equipment beyond the base air conditioning
• Emergency lighting within the tenancy (in older buildings, this may not exist at all)

Before signing a lease, it's worth having an electrician review the electrical drawings for the building and confirm what's actually being handed over. "Warm shell" provisions vary significantly between landlords, and the difference between a genuinely usable base electrical provision and a legal minimum can be tens of thousands of dollars in fit-out cost.

Circuit count: the decision that's cheapest to make early

The number of circuits your tenancy needs is determined by the intended use. A 300-square-metre professional services office has very different electrical requirements from a 300-square-metre café or a medical consulting suite. The mistake is sizing circuits to today's furniture plan, not to the realistic envelope of how the space might be used.

General guidance by tenancy type:

Office (professional services, finance, administration): Plan for power circuits at roughly 1 per 12–15 square metres of usable floor area, with separate circuits for the server room or comms room, any kitchen equipment, and dedicated circuits for large-format printers or other high-draw equipment. Data and power should be coordinated. Every workstation location needs both.

Retail: Dedicated circuits for point-of-sale infrastructure, security and surveillance systems, external signage (often overlooked until the sign goes up), and any refrigeration or display equipment. Refrigeration equipment in particular benefits from dedicated circuits; sharing a circuit with general power creates nuisance trips and shortens compressor life.

Medical and allied health: Higher power requirements for imaging equipment, autoclaves, and other clinical equipment. Many medical fit-outs also need the base electrical installation to meet specific standards around equipotential bonding in patient areas. Get electrical input at the planning stage, not when the equipment is arriving.

Hospitality and food service: Commercial kitchen equipment is the electrical planning challenge in these fit-outs. Commercial ovens, fryers, underbench refrigeration, dishwashers, coffee machines and exhaust fans all need dedicated circuits. The kitchen electrical scope is often as complex as the rest of the fit-out combined.

Sub-board location

Where the sub-board (distribution board) goes inside the tenancy is a decision that's essentially permanent once walls are built. Get it wrong and you're either running long cable runs to awkward locations, or retrofitting a second board later.

The sub-board should be:

• Accessible: in a plant room, services corridor, or other location that allows circuit breaker access without disrupting the tenancy
• Central to the electrical load: avoids long cable runs to the far end of the tenancy
• Coordinated with the builder: sub-boards take wall space and depth, and the builder needs to accommodate them in the framing design

In multi-storey commercial buildings, the sub-board location also needs to work with the riser: the vertical conduit or cable path that brings the sub-main from the main switchboard up to the tenancy level. If the riser comes out of the floor slab in one location and the sub-board is planned for the opposite end of the tenancy, that's a significant cable run that may not fit in the void.

Conduit routes: what to run before the walls close

Once plasterboard is up, adding new circuits means either chasing walls (cutting channels in the plasterboard or masonry to run new cables) or surface-mounted conduit. Both are far more expensive and disruptive than running conduit before the walls close.

The smart approach is to run more conduit than you need during the fit-out, particularly:

• Conduit sleeves through fire-rated walls: these require core drilling and fire stopping, which is straightforward during construction and a significant cost to retrofit
• Conduit from the sub-board to key locations: server room, reception desk, boardroom, any location where future cabling is likely
• Conduit or cable tray through ceiling voids: run the pathways even if you don't pull cable through them immediately

The cost of running an additional conduit during a fit-out is marginal. The cost of retrofitting it later is not.

Trade coordination: hydraulics and mechanical

Exhaust fans, hot water systems, compressors and HVAC equipment all need dedicated electrical circuits, and they all have specific installation requirements. The problem is these trades often work from their own drawings without full visibility of what the other trades are doing.

Specific coordination points:

Exhaust fans: Commercial kitchen exhaust fans and toilet exhaust typically need dedicated circuits, and the circuit capacity needs to match the motor. Some commercial exhaust fans also have interlocks with the gas system or fire suppression; these connections need to be coordinated early.

Hot water systems: Continuous flow gas HWS may not need a dedicated circuit, but heat pump or electric HWS units need dedicated circuits appropriately sized for their draw. In tenancies with multiple ablution facilities, the HWS load can be significant.

Air conditioning and HVAC: Most commercial tenancies have building-provided base air conditioning, but supplementary cooling for server rooms, plant rooms or high-density areas needs its own electrical provision. Confirm what the base-build AC provides and what the tenancy fit-out needs to supplement.

Compressors: Any tenancy with compressed air (a dental surgery, a workshop, a food production facility) needs a dedicated circuit for the compressor sized for the motor's starting current, not just its running current. Compressor starting loads are several times the running current and will trip an undersized circuit breaker.

Getting the mechanical and hydraulic drawings aligned with the electrical drawings before construction starts saves significant rework.

Data and power integration

The decision that drives more retrofit cost than almost anything else is treating data and power as separate planning exercises. In a modern commercial tenancy, data and power need to be planned together because:

• Every workstation location needs a power point and a data outlet (or a combined power and data plate)
• Meeting rooms need power and data at the table, not just at the perimeter
• Rack rooms and comms rooms need power for UPS systems, network equipment, and patch panels; this is a separate circuit from general power
• Wireless access point locations need data cabling (PoE switches power WAPs, but the cable still needs to run)

The structured cabling design should be done in parallel with the electrical design, not as a follow-up. The cable pathways (conduit, cable tray, in-wall conduit) are shared, and they need to be coordinated before walls close.

Wireless-only is rarely the right call. Some clients try to minimise structured cabling by relying on Wi-Fi for everything. This works for simple tenancies with light use, but any tenancy with more than 15–20 users, any use involving large file transfers (architecture, video production, medical imaging), or any use where network reliability is critical needs structured cabling. Wi-Fi is not a substitute for a wired backbone.

Does the existing board have capacity, or do you need an upgrade?

This is the question that sometimes derails fit-out projects when it's answered late. If you're fitting out into a tenancy that already has a sub-board from a previous tenant, that board may or may not have the capacity for your fit-out.

Signs you probably need a new or upgraded sub-board:

• The existing board has fewer than 12 circuits
• The existing board has no RCDs (older commercial tenancies sometimes have switchboards with circuit breakers only)
• The supply to the board is 32A or 40A single phase and your fit-out includes a commercial kitchen, significant HVAC, or other high-draw equipment
• The existing board is in the wrong location for your floor plan

Signs you can probably work with what's there:

• The board was installed within the last 10 years, has RCDs, and has multiple spare circuit positions
• Your fit-out is low-intensity (professional services office with no kitchen equipment, light HVAC)
• The supply to the board is 63A three-phase or better

Don't assume the existing board is adequate without having an electrician check it. The cost of confirming is minimal. The cost of discovering during construction that you need a new sub-board, and that the sub-main from the main switchboard isn't large enough to support it, is significant.

Getting the electrical drawings done at the right time

Electrical drawings for a commercial fit-out should be produced in parallel with the architectural plans, not after them. The sequence should be:

1. Architectural plan is drafted, showing room layout, wall positions, ceiling height
2. Electrical and data drawings are produced alongside, showing outlet locations, sub-board position, circuit allocation, data points
3. Both sets of drawings are issued to the builder before construction starts
4. Any coordination issues (sub-board location conflicts, conduit path clashes with structural elements) are resolved on paper, not on site

When electrical drawings arrive after construction has started, the builder has usually already made decisions (framing locations, wall positions, ceiling penetrations) that create problems for the electrical installation. Resolving those problems on site costs time and money that a proper planning process would have avoided.

If you're planning a commercial fit-out in Nunawading, Box Hill or Ringwood and want to get the electrical scope locked in early, contact us about our commercial fit-out electrical services.