Backup Generators: The Complete Walkthrough

This guide covers backup generators, rated an easy to moderate task, typically taking setup: a few hours.

Our printable card on backup generators covers the essentials at a glance — here's the fuller walkthrough, with the reasoning behind each step.

Before the step-by-step detail, here's why this is worth learning in the first place. At a glance, it's rated easy to moderate, with a difficulty of easy–moderate; time of setup: a few hours; cost of moderate — details that matter more once you're actually planning around them than they do on a first read. The rest of this article works through exactly what each of those means day to day, in more depth than a single printable card has room for, and with the reasoning behind each recommendation rather than just the recommendation itself.

How This Applies Across Property Types

This skill applies whether you're working with a suburban block or a larger rural property, though the scale and specific materials will differ. Where climate or regional conditions change the approach, that's called out in the method above rather than assumed — but as a general rule, Australian conditions (heat, water restrictions in many areas, and UV exposure on materials left outdoors) are worth factoring in even where a source guide doesn't explicitly mention them.

Sized to your actual critical loads

A generator sized to run everything at once is usually overkill and expensive — most homesteads do better sizing to the critical loads (fridge, freezer, some lighting, water pump) rather than the whole property at once.

What You'll Need

A few things matter most here:

• A generator sized to your critical load list, with some margin
• Appropriate fuel storage (petrol, diesel, or LPG depending on generator type)
• A transfer switch if connecting to household wiring (essential for safety)
• Regular maintenance supplies (oil, filters, spark plugs as applicable)

These aren't equally important, but all of them are worth building into your routine — a generator sized to your critical load list, with some margin Regular maintenance supplies (oil, filters, spark plugs as applicable) Treat this list as a routine to build rather than a one-off checklist, and it becomes second nature within a season or two.

The Method

The key things to get right:

• 1. List your critical loads and their combined running (not just starting) wattage.
• 2. Choose a generator sized with reasonable margin above that critical load total.
• 3. Install a proper transfer switch if connecting to household circuits — never back-feed through a wall socket, which is dangerous to utility workers and illegal.
• 4. Store fuel safely and rotate stock so it doesn't degrade.
• 5. Run and test the generator periodically, not just when an outage occurs — a generator that hasn't run in months may fail exactly when needed.

None of these are complicated on their own, but skipping one is a common source of trouble — 1. List your critical loads and their combined running (not just starting) wattage. 5. Run and test the generator periodically, not just when an outage occurs — a generator that hasn't run in months may fail exactly when needed. Treat this list as a routine to build rather than a one-off checklist, and it becomes second nature within a season or two.

When Things Go Wrong

A few things matter most here:

• Won't start after sitting unused — stale fuel is the most common cause; use a fuel stabiliser or rotate fuel stock, and run the generator periodically.
• Overloaded and tripping — recalculate actual running wattage of connected loads, including motor starting surge for things like fridges and pumps.
• Unsafe back-feeding into household wiring — always use a proper transfer switch, never a workaround; this is a safety hazard.
• Excessive fuel use — running a large generator for a small load is inefficient; match generator size to actual need, or consider a smaller unit for baseline loads.

These aren't equally important, but all of them are worth building into your routine — won't start after sitting unused — stale fuel is the most common cause; use a fuel stabiliser or rotate fuel stock, and run the generator periodically. Excessive fuel use — running a large generator for a small load is inefficient; match generator size to actual need, or consider a smaller unit for baseline loads. Treat this list as a routine to build rather than a one-off checklist, and it becomes second nature within a season or two.

Ongoing Timing

Best time. Set up and test before you need it, ideally right after purchase, not during your first outage.

Duration. Modern generators can run continuously for many hours per fuel tank, refuelled as needed.

Maintenance. Regular test runs, oil changes per manufacturer schedule, and fuel stock rotation.

Signs of success. Starts reliably on the first or second pull/attempt, and runs your critical loads without tripping or overloading.

These few details do most of the actual work, more than any single trick or shortcut would.

Tips & variations

A few notes worth having alongside the method above: Micro-Hydro Power Basics, Wind Power Basics, Back-feeding a generator into household wiring without a transfer switch, Letting the generator sit unused for months without a test run. These come from the same printable card and are easy to miss on a first read.

Related Guides

A few related guides worth reading alongside this one:

• Biogas Digesters
• Micro-Hydro Power Basics
• Wind Power Basics

That's the full walkthrough. The printable A4 quick-reference card for this is on the main guide page below. If something's already gone wrong, our Troubleshooting Directory indexes common problems by symptom across all 219 guides. As with every guide on this site, this is general information based on our own research and experience, not professional advice — your specific soil, climate, and circumstances will always vary from ours to some degree.

Our Solar & Off-Grid Load Estimator is a useful companion to this specific skill.

Frequently Asked Questions

→ View the printable A4 guide for backup generators