Got a customer last month who’d had his shed built, gone to get power connected, and discovered the underground trenching needed to run from the meter to the shed was going to cost more than he’d paid for the shed itself. He hadn’t planned for it. The supplier hadn’t mentioned it. The cost came out of nowhere.

Don’t be that customer. A practical guide to thinking through shed power before you build, before you order, and before the electrician arrives.

What you need before the work starts

A few pieces of information that make every subsequent decision easier.

Distance from the main supply point. Specifically, the underground cable run distance from the meter box (or sub-meter, or distribution point) to the shed. The cost of underground power runs is a function of distance and cable size, and the difference between a 10m run and a 40m run can be substantial.

Anticipated power loads. Lights, power tools, charging stations, workshop equipment, climate control. Make a list. Sum the realistic peak loads. The size of the circuit you need depends on the realistic peak, not the theoretical maximum, but you want to size with some headroom.

Three-phase versus single-phase requirement. Most home workshops can run on single-phase. Some equipment (large welders, big air compressors, some milling machines, certain dust extraction systems) needs three-phase. If you’ll ever need three-phase, plan for it now — retrofitting later is expensive.

Sub-board specification. A workshop shed almost always benefits from its own sub-distribution board, with its own RCDs and circuit breakers, so the shed wiring is isolated from the house wiring. This costs more upfront but saves complexity and improves safety.

The trenching question

Underground power cable from the main supply point to the shed is the single biggest variable cost in shed power, and it’s the one people most consistently underestimate.

Direct burial cable requires excavation to a depth specified by AS/NZS 3000 (typically 500mm in most situations, deeper in driveable areas). The cable goes in sand bedding with a warning tape above. The excavation, sand, cable, backfill, and reinstatement of any surface above adds up.

Conduit installation uses a buried conduit through which the cable runs. More flexibility for future changes, slightly higher installation cost. The conduit run itself is still in a trench at specified depth.

Overhead cable is workable for some sites and dramatically cheaper than trenching. Aesthetic considerations and ongoing exposure to weather and tree contact mean overhead isn’t always the right answer, but it’s worth considering.

For a typical residential shed 25-35m from the meter box, underground installation cost in 2026 is commonly in the A$2,500-5,500 range depending on the surface above (lawn is cheaper than concrete or pavers) and the cable size.

Sub-board sizing

The sub-board in the shed needs to handle the realistic loads, with appropriate safety devices.

For a modest home workshop — single-phase, hand power tools, basic lighting, a few outlets — a 32A or 40A sub-circuit feed with a sub-board carrying 4-6 circuits is typical. Cost for the supply and installation of a sub-board of this size is commonly A$800-1,500 plus the feed.

For a more serious workshop — heavy power tools, dust extraction, air compressor, welding equipment, comprehensive lighting — a 63A or larger feed with a more substantial sub-board is typical. The cost grows accordingly.

For three-phase workshops, the sub-board configuration is different and the cost is meaningfully higher. Reasonable budget for a three-phase 32A or 40A workshop installation is A$3,500-7,500 depending on complexity.

Lighting

Lighting is one of the most under-planned aspects of shed power. A few practical considerations:

LED is the obvious default in 2026. Long life, low energy use, comprehensive options. Modern LED batten lights and high-bay fittings cover most workshop needs.

Light levels matter for the work. General workshop areas want 300-500 lux. Detailed bench work wants 750-1000 lux. Specialised areas (machining, fine joinery) can need 1500+ lux. Plan light fixture density accordingly.

Switching arrangements deserve thought. Multiple switch points for lights you’ll use repeatedly. Separate switching for different work zones so you can run only the lighting you need.

Emergency or backup lighting is worth considering for sheds used for sensitive activities. Power failures during welding or machining are inconvenient at best.

Daylight access. Don’t forget the value of natural light. Properly placed skylights or roof translucent panels reduce daytime lighting load and improve work conditions.

Outlets

Workshop outlet planning often suffers from “not enough” syndrome. Some practical guidance:

Bench outlets every 1-1.5m along work surfaces. Long extensions across benches are inconvenient and create tripping hazards.

Multiple separate circuits across the workshop. If one circuit trips, the lights don’t go out. Specifically, lighting circuits separate from power circuits, and major equipment on dedicated circuits.

Dedicated circuits for major equipment. Welders, large compressors, machine tools all benefit from dedicated circuits with appropriate amperage. The motor start currents of large equipment can trip shared circuits even within nominal rating.

Outdoor outlets for outdoor work, including outdoor lighting and outdoor power for occasional use.

RCD protection on all socket outlet circuits per AS/NZS 3000. This is mandatory and not negotiable.

EV charging and battery storage

A workshop shed is increasingly a natural place to install EV charging or battery storage equipment. Worth thinking about even if you’re not installing it immediately:

EV charging at home increasingly happens in or adjacent to the shed or garage. If you’ll have an EV charging point now or in the future, plan the cable capacity to support it. A typical Level 2 charger pulls 32A; including this in the load calculation now is much easier than uprating the feed later.

Solar inverter location. If you have or plan to install rooftop solar, the inverter often lives in a shed for thermal reasons. Plan the wiring runs accordingly.

Battery storage. Home battery installations often happen in sheds or garages. The thermal management, ventilation, and clear access requirements need planning if battery storage is in your future.

Permits and certifications

Power work in Australia requires licensed electrical contractor involvement. A few specifics worth knowing:

The electrician needs to be licensed for the type of work, which varies by jurisdiction.

The work usually requires a Certificate of Electrical Safety (or equivalent) on completion. Keep this document — you’ll need it for future property transactions and insurance.

Higher-capacity work, three-phase work, and any work affecting the main supply may require additional inspections and certifications. The electrician will know what applies to your specific job.

Solar interaction, battery storage, EV charging — all of these have specific compliance requirements that the electrician needs to know about in advance.

Budget reality check

For a workshop shed 25-35m from the supply point, single-phase, basic LED lighting, sensible outlet provision, sub-board with appropriate RCD protection — realistic 2026 budget is A$4,500-8,500 all-in including trenching.

For more substantial workshops with three-phase, heavy lighting, comprehensive outlet provision — A$8,500-18,000 is typical.

Cyclone-region or remote-location installations can run substantially higher. Solar/battery/EV integration adds substantially.

The cost is real and shouldn’t be a surprise. The buyers who get into trouble are the ones who didn’t include the power cost in their shed budget, then have to make compromises on power capability to fit the residual budget. The shed without good power isn’t half as useful as the same shed with proper electrical infrastructure. Budget for it from the start.