At a glance: manual vs automatic changeover switches
- A generator changeover switch lets you change the electrical supply between mains power and a backup generator without the two supplies being connected at the same time.
- A manual changeover switch requires you to make the switch yourself when mains power fails and again when it returns.
- An automatic transfer switch (ATS) detects a mains failure and manages the changeover automatically when paired with a compatible generator and correctly configured system.
- Manual changeover can suit occasional backup power, particularly when you're usually there to start the generator and manage the switch.
- Automatic changeover makes more sense when backup power needs to come on without you being there or when reducing downtime matters.
A generator changeover switch gives you a controlled way to move between your mains electricity supply and backup generator power.
The main decision is whether you want to manage that changeover yourself or have it happen automatically.
For occasional power cuts, or where you may want to unplug non-essential items first, a manual switch may be all you need if you’re happy to start the generator and operate the changeover yourself. An automatic transfer switch removes much of that manual process, provided you have a compatible generator and correctly configured setup.
The right option depends on how quickly you need backup power, whether you’ll be there during an outage and what needs to keep running.
What does a generator changeover switch do?
A changeover switch controls whether your electrical installation is supplied by the mains or your generator.
Its job is to move between those two power sources while keeping them separate during the changeover.
A changeover switch doesn't generate power itself and doesn't increase your generator's output. You still need a generator that's properly sized for the electrical load you want to support.
What's the difference between a manual and automatic changeover switch?
The main difference is whether you control the changeover or the system does it for you.
| Feature | Manual changeover switch | Automatic transfer switch (ATS) |
|---|---|---|
| Changeover | You operate it manually | Happens automatically with a compatible setup |
| Generator starting | Usually started manually | Compatible generator can be signalled to start automatically |
| When mains returns | You switch the supply back | System can transfer back automatically |
| Best suited to | Occasional backup where someone is available | Backup where automatic response is important |
| Generator compatibility | Depends on the setup | Requires specific ATS compatibility |
Neither option is better in every situation. A manual switch may be all you need for occasional backup, while automatic transfer makes more sense when you don’t want an outage to depend on someone being there to manage it.
How does a manual generator changeover switch work?
With a manual changeover switch, you decide when the electrical supply moves from the mains to your generator.
If mains power fails, you’ll need to start the generator and operate the changeover switch according to the system instructions. When mains electricity returns, you switch the supply back and shut the generator down correctly.
The main advantage is simplicity and the ability to unplug any non-essential items first should you wish to do so.
If backup power is only needed occasionally and you’re likely to be there when an outage happens, you may not need an automatic system.
The trade-off is that backup power won’t come on until someone starts the generator and manages the changeover.
How does an automatic changeover switch work?
An automatic transfer switch, or ATS, monitors the mains electricity supply. When a failure is detected, it can signal a compatible generator to start before transferring the electrical load to generator power.
When the mains supply returns, the system can switch back and allow the generator to shut down.
That makes automatic transfer useful when you want essential equipment to regain power without having to manually start the generator and operate a switch.
An automatic transfer switch needs to be compatible with the generator and correctly configured to manage the changeover between mains and backup power.
When is a manual changeover switch the better choice?
Manual changeover is worth considering when backup power is occasional and you're comfortable managing the process yourself.
For example, you might use a generator during an occasional household power cut, in a workshop or somewhere else where someone will normally be available to start it.
You also may also prefer to unplug an oven or other non-essential items first before starting the generator which would lessen the load and reduce the size of generator needed.
In those situations, automatic transfer may add complexity that you don't actually need.
A petrol generator can suit this kind of occasional backup, depending on your power requirements. Petrol generators are available across a wide range of outputs, so they can suit anything from lighter backup requirements to more demanding portable applications.
If you'd prefer a choice of fuels, a dual-fuel generator gives you the option of petrol or LPG. Changeover and fuel choice are separate decisions, though, so the generator and switching arrangement still need to suit your electrical setup.
When is an automatic transfer switch worth considering?
Automatic transfer makes more sense when you don’t want backup power to depend on someone being there to switch it over.
That could be because:
- You want essential equipment backed up while you're away
- You want to reduce the amount of manual intervention during a power cut
- Outages could affect equipment that you'd prefer to restore quickly
- The generator forms part of a more permanent backup-power setup
The generator needs to support ATS for this to work. Electric start or remote start alone doesn't necessarily mean a generator can be controlled by an automatic transfer switch.
If you're choosing an ATS, check ATS compatibility carefully before buying, as the generator and transfer switch need to work together.
Can you use a changeover switch with a petrol or dual-fuel generator?
Yes, depending on the generator and the type of changeover setup.
A manual changeover arrangement doesn't require a generator to automatically respond to a mains failure in the way an ATS does. If you want automatic changeover, however, you'll need a generator with the correct ATS compatibility.
Some petrol generators support ATS, so you don't automatically need a diesel generator for automatic home backup.
For dual-fuel, check compatibility separately from the fuel specification. Being able to run on petrol and LPG doesn't by itself tell you whether the generator supports automatic transfer.
When is diesel the better option?
A diesel generator can make more sense when your backup requirements involve heavier loads, longer running periods or more demanding applications.
That can make diesel a stronger fit for some larger standby setups, but the type of changeover switch doesn’t determine the fuel you need.
Choose the generator around your power requirements and expected use first.
For lighter or occasional backup, petrol or dual-fuel may already give you the output and flexibility you need.
What size generator do you need for a changeover switch?
The same sizing principles apply whether the changeover is manual or automatic.
Start by deciding what actually needs power during an outage. You may only need to support essential appliances and equipment rather than everything you normally use.
Then consider:
- The combined running wattage
- Any additional starting wattage
- Which equipment may operate at the same time
- The generator’s rated output
- Any extra capacity needed for changing loads
Don’t choose the generator based on the rating of the changeover switch alone.
The generator needs to be sized around the equipment it will actually power.
Manual vs automatic: which should you choose?
To decide which option suits you, ask:
- Will someone normally be there when the mains power fails?
- Are you comfortable starting the generator and changing over manually?
- How quickly do you need backup power?
- Does essential equipment need power while you're away?
- Does your generator support ATS?
- How much equipment needs to remain powered?
- Is the generator correctly sized for that load?
- How will the changeover system be installed?
Choose manual changeover when you want a straightforward backup setup and are happy to manage an outage yourself.
Choose automatic transfer when you want a compatible generator to respond to a mains failure without relying on someone being there to operate it.
Who should install a generator changeover switch?
A generator changeover switch forms part of the connection between your backup power source and electrical installation, so correct installation matters.
Use a suitably qualified electrician to assess the setup and carry out the necessary electrical work.
They can also confirm whether the generator, changeover equipment and electrical supply are properly matched.
If you’re unsure whether an automatic changeover is the better fit for your setup, use our chat system to work through your power requirements and narrow down the right option.
