What is a Residual Current Device (RCD)?

A residual current device (RCD) is a device designed to protect against the risks of fires and electrocution if there is a fault with an electrical device or power tool.

They are primarily designed to protect a human from hazardous electric shocks and can prevent you from being electrocuted if you touch something live, such as a bare wire.

An RCD can also prevent electrical fires by shutting off the supply to an item if there is a fault with it. Ordinary fuses and circuit breakers can often not provide this high level of protection.

This is why many of our Speedy tool bundles include a residual current device as standard, and we recommend hiring them with any other power tools, too.

Our RCD units have test and reset functions so you can check everything is in order before using your power tools. If you hire products from Speedy, they’re all checked before they go out, as well.


Why are RCDs used?

Issues with electrical items are common. They can come about if:

  • There is damage to a cable or plug
  • A wire is damaged during use, i.e., cutting through a lawnmower cable when mowing grass
  • There is an issue with the electrical source (such as the mains plug socket)
  • Water or any other liquid comes into contact with the source or tool
  • A tool overheats, causing electric current to flow to the earth

These faults can be life-threatening, especially if you come into contact with exposed live wires. Electrical faults can also cause fires.

Using an RCD power breaker can reduce this risk. The risk isn’t necessarily eliminated, as a small shock can still occur just before an appliance is shut off, but it will reduce the risk of further damage and electrocution.


How does an RCD work?

An RCD will react to the power surge created if there is a fault with an electrical item. It will then disconnect the electric current.

These power surges can either flow via a person or down to earth through the appliance.

An RCD is designed to respond quickly, much quicker than built-in fuses can. It prevents harm to a person primarily, allowing you time to react to the problem.


Do I need an RCD?

UK mains voltage is 230v so 110v equipment does not require an RCD. We highly recommend using an RCD when using a 230v or above tool or equipment.

If there is water present (such as with a pressure washer) or there is a risk of damage to the cable (as with saws or other blades) then an RCD is essential.

It is also a good idea to use an RCD if you are using an extension lead or another form of additional electrical device. This is because the addition of another device increases the risks of danger.

Burns and electric shocks can be really serious, so it is always best to be safe if ever in doubt.




Yes. Speedy Hire, the UK's leading tool hire company, have a range of RCD units for hire nationwide.

With more than 200 service centres across the nation, hire counters in selected B&Qs and nationwide 4-hour delivery, RCD hire has never been easier.

RCD units are also included in many of our bundles and recommended when using a wide range of our hire tools.

Open a Speedy account today online or in-store for access to our full range of products and bespoke prices.

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