EV Charging in Apartment Buildings: Backbone, Load Management and Billing

The most reliable way to bring EV charging into an apartment building is to install a shared electrical backbone through the car park first, use load management so chargers share the building's available capacity, and meter each charger so residents pay for their own electricity. Individual chargers are then added bay by bay as owners buy EVs. This approach avoids the capacity problems, messy cabling and fairness disputes that follow when residents install chargers one at a time. Here is how our team plans each layer.

Why one-off chargers cause problems

When the first EV owner in a building asks for a charger, the quick answer is often to run a cable from their unit's meter to their parking bay. That can work once. Repeated across a building, it creates:

• long, separate cable runs crossing common property and fire-rated walls;
• first-come, first-served use of spare supply capacity, leaving later residents with none;
• chargers of different types with no coordination, so the building's maximum demand can be exceeded when several run together;
• unclear responsibility for maintenance, insurance and removal when an owner sells.

What a backbone is

A backbone is building-owned electrical infrastructure that brings capacity close to every parking bay: a supply from the main switchboard to distribution boards on each car park level, plus cable tray or busway with connection points along the rows of bays. When a resident wants a charger, an electrician connects it to the nearest point instead of running a new cable across the building.

The backbone can be installed in stages, for example one car park level at a time, but it should be designed once for the whole building so later stages fit. Design starts with the building's supply rating, its measured maximum demand and the space available in the switch room.

Planning for how many EVs, and when

A backbone is designed around the building's future, not its first EV. A short resident survey about current EVs, planned purchases in the next few years and parking arrangements gives the committee a realistic picture. From there, the design can:

• size the backbone and switch room works for every bay, while energising car park levels only as demand appears;
• allow for visitor bays or a shared charger for residents whose own space is hard to reach;
• identify bays where cable routes are difficult or expensive, so costs are known before owners commit;
• set a sequence for later stages so each resident's request follows the same simple process.

Designing once and building in stages spreads cost over time without locking the building into an arrangement that cannot grow.

Load management: sharing limited capacity

Most buildings cannot supply every bay at full power simultaneously, and they do not need to. Load management measures the building's total load and divides spare capacity among the chargers in use, reducing each charger's current when demand is high and restoring it when demand falls. Static systems set a fixed limit for the charging group; dynamic systems adjust in real time to what the rest of the building is using.

This works because apartment cars are parked for long periods. The table shows roughly how little energy typical daily driving needs, assuming a common consumption of 15-20 kWh per 100 km and ignoring charging losses:

Even when load management halves the available power, most residents' cars are topped up well before morning.

Billing residents fairly

Once chargers draw from the common-property supply, the owners corporation pays for that electricity, so it needs a fair way to recover the cost. The main options are:

• Metered chargers with a billing system: each charger records energy per user, residents identify themselves with a card or app, and the building recovers costs per kWh. This is usually the fairest approach.
• Sub-meters recharged through levies: workable for small buildings, but more administration for the strata manager.
• Flat fees: simple, but unfair to low-mileage drivers and harder to justify as EV numbers grow.

The committee also needs to decide who pays for the backbone. A common approach is to fund it as shared infrastructure, since every lot gains the option of charging, and have individual owners pay for their own charger and its connection. Whatever rate is charged per kWh should cover the electricity itself plus any billing platform fees, and it should be reviewed when the building's electricity contract or tariff changes.

Approvals, by-laws and safety

The owners corporation will typically need a resolution approving the backbone and a by-law covering how owners connect chargers, which charger types are allowed, maintenance, insurance and what happens when a lot is sold. Fire safety in the car park, cable routes through fire-rated elements and the building insurer's requirements should all be considered. All work must be carried out by licensed electricians, and your strata manager can advise on meeting requirements. Keep a register of every charger connected to the backbone, with its compliance paperwork and the lot it serves, so future committees know exactly what is installed and who is responsible for it.

Staging and indicative costs

These services from our energy market show how the stages fit together. All prices are indicative and confirmed after a site assessment.

Next steps

Start by surveying residents about current and planned EV ownership and gathering the building's electricity bills. You can estimate charging energy for typical drivers with our EV charging calculator and see how we approach charger installations on the EV chargers page. When the committee is ready, request a quote and our team will assess the switch room, supply capacity and car park layout.

Frequently asked questions

Can the building's solar power the EV chargers?

It can help, but only to a point. Most apartment residents charge in the evening and overnight, after solar production has finished, so a common-property solar system mainly offsets daytime loads. Chargers on the common-property supply can use surplus solar for cars parked during the day, such as those of residents working from home. A shared battery can store some daytime surplus, but it must also be sized for the building's other loads.

What happens to a charger when an owner sells their apartment?

That should be set out in the building's by-law before the first charger is connected. Common approaches include the charger staying with the lot and passing to the buyer, or the owner arranging removal by a licensed electrician and making good the connection point. Clear rules protect the owners corporation from abandoned equipment and give buyers confidence about what they are purchasing.

Will the building need a bigger electricity supply?

Not always. Load management often allows a building to add many chargers within its existing supply, because charging is spread across long overnight parking periods. A capacity assessment based on measured maximum demand shows how much headroom exists. If the building later reaches its limit, the options include tighter charging schedules or a supply upgrade, which needs network approval and can take time, so it pays to know the numbers early.