How Much Switchboard Capacity Does a Strata Building Actually Have?

How much spare switchboard capacity does a strata building actually have? It depends on the size of the common switchboard or switchroom serving the block, how many units draw off it, and how much of that capacity is already committed to lifts, common area lighting, fire systems and car park loads, and the only reliable way to know is a proper assessment rather than a guess based on the building's age. Older blocks built before EV chargers, heat pump hot water and induction cooking became common were sized for a very different demand profile, and that gap is what triggers most common property switchboard upgrades today.

⚡ Quick Answers: Strata Switchboard Capacity

• How is capacity calculated for a whole building? Under AS/NZS 3000's diversity method, not by simply adding every unit's peak demand together, because not every unit draws its maximum load at the same moment.
• What actually triggers a strata switchboard upgrade? Rising per unit demand from EV chargers, heat pump hot water and induction cooking across many units at once, an ageing main switchboard or riser sized for a different era, or a defect notice.
• Who arranges and pays for it? The owners corporation, funded through the capital works fund or a special levy once quotes are obtained and the appropriate approval is given.
• How do you measure real demand rather than calculated demand? Power logging at the building's main incomer over one to two weeks, which shows what the building actually uses rather than a worst case calculation.
• Does every unit's upgrade require a whole building upgrade? No. An individual lot's own switchboard or circuit work is separate from the common property switchboard and riser capacity that feeds the whole building.
• Does this ever involve the network distributor? Yes, if the building's actual incoming supply from Ausgrid or Endeavour Energy needs increasing, rather than just the internal common property wiring.

1. Why a whole building's capacity is not just the sum of every unit

If you added up the theoretical maximum demand of every unit in a fifty unit building running flat out at once, you would get a number far higher than what the building's actual main switchboard needs to carry, and sizing to that theoretical peak would be wildly uneconomical. AS/NZS 3000 accounts for this with a diversity method for multiple domestic electrical installations, which recognises that residents do not all run their ovens, air conditioners and EV chargers at exactly the same moment, and calculates a realistic after diversity maximum demand instead. This is the same principle behind our guide to how much spare capacity a single home actually has, scaled up to a whole building rather than one household.

2. What is actually eating capacity in older strata buildings

The individual appliances driving rising demand in strata buildings are the same ones affecting single homes, EV charging, ducted air conditioning, induction cooking and heat pump hot water, but in a strata building the effect compounds across dozens of units rather than one household. Our maximum demand guide covers those individual loads in detail. What is specific to strata buildings is that a main switchboard or riser system designed decades ago, before any of these appliances were common, can end up genuinely undersized even if no single unit's own wiring has changed, simply because the building's aggregate demand has crept up unit by unit over several years.

3. Power logging: measuring what the building really uses

Rather than relying purely on a calculated figure, the practical first step in assessing a strata building's real headroom is power logging at the main incomer, a monitoring device left in place for one to two weeks to record actual demand through a realistic mix of weekdays, weekends and peak evening periods. This measured figure is often meaningfully different from a conservative calculated one, and it is the same technique covered in more detail in our guide to power logging and maximum demand, applied here at building scale rather than for a single EV charger installation.

4. Common switchboard and riser upgrades versus individual unit work

It is worth being clear about what actually needs upgrading. An individual lot owner adding an EV charger or heat pump hot water system to their own unit is generally responsible for their own switchboard and circuit work, the same as any homeowner, covered in our guide to EV charger installation in strata buildings. A common property upgrade is a different and larger project: the main switchboard, switchroom or riser cabling feeding the whole building, which is the owners corporation's responsibility because it serves every lot rather than one. Confusing the two is a common source of disputes at committee level, and our guide to strata electrical responsibility covers where that line actually sits.

5. When a Level 3 design and network application become necessary

Most capacity problems inside a strata building can be solved within the existing incoming supply, by reorganising the common switchboard, adding load management, or staging individual unit upgrades sensibly. Genuine network level constraints, where the building's actual incoming supply from the distributor is the bottleneck rather than the internal wiring, require Level 3 design work and a formal application to Ausgrid or Endeavour Energy, a path covered in detail in our guide to Level 3 design for capacity upgrades. If you are not sure which network area your building sits in before starting that conversation, you can check your network area in seconds with our postcode checker.

6. Funding and approval: capital works fund, special levy and owners corporation sign off

A common property switchboard or riser upgrade is a capital works item, typically funded from the building's capital works fund if the balance allows, or through a special levy voted on at a general meeting if it does not. Because the work affects every lot's supply, it generally needs formal owners corporation approval rather than committee delegated authority alone, particularly once quotes reach a material cost. Getting a proper power logging study and a clear scope from a Level 2 ASP before that meeting gives owners a real number to vote on, rather than an open ended estimate.

Why it's Level 2 ASP work

Any work touching a strata building's consumer mains, metering or the connection point to the network is Level 2 ASP territory, which most common property switchboard and riser upgrades eventually involve given they sit upstream of every individual unit's own board. Coordinating that work with a single accredited contractor, rather than splitting it across a standard electrician and a separate ASP, keeps a large multi lot job from stalling on a licensing gap partway through.

How High Demand Electrical helps

High Demand Electrical is one of Sydney's most trusted Level 2 ASPs for exactly this kind of common property work. We start with a power logging study rather than a guess, give the owners corporation a genuine measured picture of the building's headroom, and scope whether the fix sits entirely within the common switchboard or needs a Level 3 network application. As a licensed local team, not a call centre, we coordinate access and timing around occupied units and shared spaces, and provide the documentation a committee needs to put a real number to a vote.

Strata Switchboard Capacity FAQs (Sydney)

How long does a power logging study take for a whole building?

Typically one to two weeks, long enough to capture a realistic mix of weekday, weekend and peak evening demand rather than a single unrepresentative day.

Can a strata committee approve a switchboard upgrade without a full meeting?

Routine maintenance can often be approved under delegated authority, but a capital works item of material cost, which most switchboard or riser upgrades are, generally needs a general meeting vote.

Does adding EV chargers in a few units always mean the whole building needs an upgrade?

Not necessarily. Load management and staged individual installations can often absorb early EV uptake without touching the common switchboard, and our strata EV charger guide covers those options.

What is the difference between a calculated and a measured maximum demand?

A calculated figure applies standard diversity factors from AS/NZS 3000 to a worst case load list, while a measured figure comes from actually logging the building's real demand, which is usually the more accurate number to plan an upgrade against.

Who owns the common switchboard in a strata building?

The owners corporation, as part of common property, which is why upgrades to it are funded and approved at the building level rather than by an individual lot owner.

If your building's EV chargers, heat pump uptake or an ageing switchboard have your strata committee asking questions, book a strata capacity assessment with High Demand Electrical or call 0402 559 777. Every job starts with a proper site visit and, where useful, a power logging study, so the committee has real numbers before any vote.