Although not a guarantee of absolute safety, you should use an RCD.
Answered by Rupert, Electrical Safety Expert
Using an RCD will help to protect you from dangerous electric shocks. Although not a guarantee of absolute safety, it limits the time current can flow through the body if a person comes into contact with a live source of electricity.
We strongly recommend that anyone using electrical appliances in areas of increased shock risk, such as gardens, should ensure that they are protected by an RCD, preferably one fitted in the main household fusebox/consumer unit.
Alternatively, a dedicated RCD-protected socket or a plug-in RCD should be used. You can buy these from most DIY stores.