Air conditioning and heat-pump systems are among the most electrically demanding loads in a modern home or commercial building. A standard split-system might draw 10 to 20 amps at start-up; a ducted inverter system or a multi-head heat-pump installation can pull considerably more, particularly during compressor start cycles. Plugging those loads into a general-purpose circuit — or worse, daisy-chaining them from an existing power run — is a recipe for nuisance tripping, premature breaker wear, and potential fire risk. SynthWire wires HVAC plant the right way: dedicated circuits from the board, correctly rated cabling, and isolation devices sized to match the equipment's stated full-load current. Every installation is certified under AS/NZS 3000 Wiring Rules, and every certificate of compliance is lodged and handed to you before we pack up.
Dedicated circuits and switchboard allocation
The starting point for any HVAC electrical job is the switchboard. We assess your existing board capacity before a single metre of cable is pulled. If you have spare ways and sufficient main fuse rating, we allocate a dedicated circuit breaker — correctly rated for the equipment's maximum demand plus a safe operational margin. If the board is full or the main fuse is under-rated for the new combined load, we tell you plainly, price the upgrade, and do it properly before the HVAC unit goes in. There is no point in a brand-new $8,000 ducted system sitting on a 20-amp circuit that trips every afternoon in summer.
For larger installations — commercial split-system banks, multi-zone ducted systems, industrial process chillers — we perform a full load calculation and may install a dedicated sub-board for the mechanical plant. This keeps HVAC faults isolated from the rest of the building's circuits and makes future servicing straightforward. Your HVAC technician will thank you for it on every return visit.
Isolation switches and safety compliance
AS/NZS 3000 and the manufacturer installation manuals for virtually every HVAC brand require a local isolating switch within sight of the outdoor condenser or compressor unit. This is not optional — it is a mandatory safety device that allows service technicians to de-energise the unit locally before working on the refrigerant circuit or electrical components. SynthWire fits weatherproof isolators rated for the equipment's full-load current, mounted at the correct height and within the required distance from the unit. We also ensure the indoor head unit's wiring is correctly terminated, the inter-unit control cable is routed away from power cable to avoid interference, and all penetrations through walls and roof spaces are sealed and fire-stopped to code.
Thermostat and controls wiring
Modern HVAC controls range from a simple single-zone wall thermostat to multi-zone BMS-integrated systems with occupancy sensing, humidity control, and remote scheduling. Whatever your HVAC installer specifies, SynthWire can run the low-voltage control wiring cleanly and correctly. We coordinate directly with your installer to confirm wire gauge, core count, and termination requirements before we pull any cable — because pulling control cable after the walls are closed is expensive for everyone. For smart thermostat installations (Nest, Ecobee, Daikin's intelligent controllers, and similar), we verify that the existing wiring supports the new controller's requirements, add a C-wire where necessary, and label every terminal clearly so future servicing is a ten-minute job rather than a guessing game.
Working alongside your HVAC installer
The best HVAC electrical outcomes happen when the electrician and the HVAC installer communicate before anyone picks up a tool. SynthWire actively coordinates with your mechanical contractor to establish the sequence of works: we rough-in the dedicated circuit and any sub-board infrastructure first, the HVAC crew installs the mechanical equipment, and we return to terminate, test, and certify. This staged approach avoids the all-too-common situation where the mechanical team has finished and the electrician is still chasing condenser supply through a wall full of ducts. If your HVAC installer does not have a preferred electrician — or if the sparky they usually use is unavailable — call SynthWire. We have worked alongside enough HVAC crews to understand what they need and when they need it.
- Dedicated HVAC circuits sized to full-load current with appropriate overload protection
- Weatherproof local isolation switches at condenser and compressor units
- Multi-zone control cable routed and labelled to AS/NZS 3000 and manufacturer specs
- Thermostat and smart-controller wiring including C-wire additions
- Switchboard upgrades and sub-board installation for large plant loads
- Staged works coordination with your mechanical HVAC contractor
Frequently asked
Possibly — but we would never assume. SynthWire checks your board capacity, the circuit's existing load, and the equipment's stated maximum demand before we confirm. If there is capacity headroom, we allocate a dedicated breaker on the existing board. If the board is full or the mains rating is marginal, we price the upgrade transparently before any equipment goes in. Running an air conditioner off a shared circuit is a leading cause of nuisance tripping and premature breaker failure — it's false economy.
Always — it's a code requirement under AS/NZS 3000, and every reputable HVAC manufacturer specifies it in their installation manual. We fit weatherproof, correctly rated isolators within the mandatory sight-line distance of the unit. This is what allows your HVAC technician to safely de-energise the plant before opening any panel. Skipping it is a compliance failure and a safety hazard; SynthWire will not leave site without it in place.
Absolutely — that coordination is standard practice for us. Give us your HVAC installer's contact and we'll sort the sequence directly: we rough-in circuits and infrastructure first, your mechanical crew installs, we return to terminate, test, and certify. Most jobs run smoothly when the two trades have spoken before day one. If you're planning a new HVAC installation, get us involved at the quoting stage and we can confirm electrical requirements before your HVAC crew even shows up.