You’re turning your shed into a workshop. You need power. The electrician asks “how many circuits and what capacity?”

Most people say “just put in a couple of outlets” and end up tripping breakers constantly or unable to run multiple tools simultaneously.

Here’s how to plan power properly so your workshop actually works.

Understanding Circuits and Load

A circuit is a single run of wiring from your switchboard to outlets. Each circuit has a capacity limit (usually 10A, 15A, or 20A for standard circuits) before the breaker trips.

Key concept: Multiple tools on the same circuit share that capacity. Running two high-draw tools simultaneously on one circuit often trips the breaker.

Your goal is enough circuits that you can run the tools you actually use simultaneously without overloading any single circuit.

What Your Tools Actually Draw

Common workshop tools and their approximate draw:

Power tools:

• Table saw: 10-15A (1500-2000W)
• Circular saw: 10-12A
• Drop saw: 10-13A
• Planer: 8-10A
• Router: 8-12A
• Angle grinder: 6-10A
• Drill: 3-8A depending on size
• Orbital sander: 2-4A
• Jigsaw: 3-5A

Shop equipment:

• Dust collector: 10-15A
• Air compressor: 15-20A (requires 15A or 20A dedicated circuit)
• Welder: 15-20A minimum, up to 32A for larger units
• Workshop heater: 10-15A
• LED shop lighting: 1-3A total

Reality check: You won’t run all these simultaneously. But you might run table saw + dust collector + lights. That’s 25-30A load, requiring at least two separate 15A circuits.

Minimum Practical Setup

For basic workshop doing woodworking or general projects:

2x 15A circuits with 4-6 outlets each. This lets you run one high-draw tool plus dust collection plus lighting without overloading.

Cost: $800-1,200 for materials and licensed electrician.

This is the bare minimum. You’ll still need to be conscious of what’s running simultaneously, but it’s functional.

Better Setup for Serious Use

If you’re using the workshop regularly and have multiple high-draw tools:

3x 15A or 20A circuits:

• Circuit 1: Bench area outlets (stationary tools, dust collector)
• Circuit 2: Mobile tool outlets (drills, sanders, other hand tools)
• Circuit 3: Dedicated lighting and auxiliary (fan, heater, radio)

This provides flexibility to run most combinations of tools without circuit juggling.

Cost: $1,200-1,800 depending on shed distance from main switchboard.

When You Need Dedicated Circuits

Some equipment requires dedicated circuits not shared with anything else:

Air compressor (15A-20A): Startup surge can trip breakers if other loads are present. Needs dedicated circuit.

Welder (15A-32A depending on size): Always needs dedicated circuit. Larger welders may require three-phase power (different discussion entirely).

Large dust collection (20A): Industrial dust collectors need dedicated power.

Kilns or furnaces: If you’re doing ceramics, metalworking, or glasswork, dedicated circuits essential.

Circuit Placement and Outlet Layout

Don’t just cluster all outlets in one area. Think about tool locations:

Bench outlets: 2-3 double outlets along workbench for stationary tools and charging.

Ceiling outlets: 1-2 outlets at ceiling height for dust collector or drop-cord suspension.

Floor-level outlets: Useful for standing tools (table saw, drop saw stands) without cords stretching across workspace.

Opposite wall outlets: Allows working from different areas without extension cords.

Electricians default to wall mounting at standard height. Tell them you want outlets where you’ll actually use them based on your shop layout.

Three-Phase vs Single-Phase

Most residential properties have single-phase power. Workshop tools are designed for this.

Three-phase power (available in some industrial areas or can be specially installed) allows running larger industrial equipment but costs significantly more to install.

When you need it: Commercial-grade machinery, large dust collection systems, industrial welders.

When you don’t: Typical home workshop using consumer or prosumer tools.

Installing three-phase power to a residential shed costs $5,000-15,000+ depending on your situation. Not worth it unless you’re running industrial equipment.

Subboard vs Direct Circuits

Direct circuits: Run individual circuits from your main house switchboard to shed outlets. Simpler, cheaper for short distances (under 20m).

Subboard in shed: Run a single heavy cable to shed, install a subboard, then distribute circuits from there. Better for longer distances (over 20m) or if you want future flexibility to add more circuits easily.

Subboard costs more upfront ($1,500-2,500 vs $800-1,500 for direct circuits) but makes future expansion easier and reduces voltage drop over long runs.

Voltage Drop Considerations

Long cable runs cause voltage drop. For a shed 30-40m from your house, this matters.

Tools operate less efficiently on reduced voltage. Motors strain, lights dim when high-draw equipment starts.

Solutions:

• Heavier gauge cable (reduces resistance)
• Higher voltage supply (240V maintains usable voltage better than 120V over distance)
• Subboard rather than long individual circuit runs

Your electrician should calculate voltage drop for your specific distance and load. If they don’t mention it, ask.

RCD Protection

Residual Current Devices (RCDs) are mandatory in Australia for power outlets. They protect against electrocution by detecting current leakage.

Your shed circuits need RCD protection either at main switchboard or at shed subboard level.

This is non-negotiable — it’s required by electrical safety regulations and genuinely life-saving if you damage a cable or tool.

Lighting as Separate Circuit

LED workshop lighting draws minimal power (2-3A total for most shed workshops) but should be on separate circuit from power tools.

Why: When you trip a circuit running tools, you don’t want to lose lighting too. Separate lighting circuit means lights stay on even if tool circuit trips.

Plus you can have lighting on without energizing tool circuits for security or when you’re in the shed but not using power tools.

Future-Proofing

Workshop needs grow over time. You buy more tools. You upgrade to larger equipment. You add features.

Planning for this upfront costs less than retrofit later:

Install conduit: Even if you’re only running 2 circuits initially, install conduit sized for 4-5 circuits. Pulling additional wires through existing conduit is cheap. Trenching and installing new conduit later is expensive.

Oversized subboard: If installing subboard, get one with spare circuit capacity (8-12 ways even if you’re only using 4 initially). Adding circuits later is simple if space exists.

Document everything: Photos and notes about circuit routing, outlet purposes, and breaker locations. Future-you will appreciate this.

Realistic Cost Expectations

Basic 2-circuit setup (directly from house):

• Materials: $300-500
• Licensed electrician: $500-700
• Total: $800-1,200

Better 3-circuit setup with subboard:

• Materials: $600-900
• Licensed electrician: $900-1,500
• Total: $1,500-2,400

Comprehensive 4-5 circuit setup with subboard, dedicated circuits for compressor/welder:

• Materials: $1,000-1,500
• Licensed electrician: $1,500-2,500
• Total: $2,500-4,000

Distance from house to shed affects cost — longer runs need more cable and more labour for trenching.

DIY Limitations

In Australia, only licensed electricians can do electrical work beyond changing light bulbs. Attempting DIY electrical work is illegal and dangerous.

What you can do: Trench for conduit runs (electrician still does conduit installation). Plan layout and outlet locations. Install shed before electrical (easier to work before internal walls/benches are built).

What you can’t do: Any actual electrical connections, breaker installation, or wiring work. Don’t try. Hire a proper sparky.

Getting Quotes

Tell electricians:

• Shed size and distance from main switchboard
• What equipment you’re running (list tool types and approximate power ratings)
• Whether you want subboard or direct circuits
• How many outlets and where
• Any dedicated circuit requirements (compressor, welder, etc.)

Get 2-3 quotes. Cheapest isn’t always best — you want someone who asks questions about your actual needs and suggests appropriate solutions.

The Bottom Line

For typical home workshop doing woodworking or general projects: 3x 15A circuits with strategic outlet placement is the sweet spot. Enough capacity to run any reasonable combination of tools, not overkill that wastes money.

If you’re running welders, large compressors, or industrial equipment, bump up to 4-5 circuits with dedicated 20A circuits for high-draw equipment.

Spending $1,500-2,500 on properly planned power is worthwhile. Spending $800 on minimal power then dealing with constant breaker trips and inability to run tools simultaneously is false economy.

Get it right from the start and your workshop will be functional and frustration-free. Get it wrong and you’ll be unplugging tools to make room for other tools every time you work.