Modern AEDs are very reliable and will not allow a shock to be given unless it is needed. They are extremely unlikely to do any harm to a person who has collapsed in suspected SCA. They are safe to use and present minimal risk to the rescuer. These features make them suitable for use by members of the public with modest (or even no training), and for use in Public Access Defibrillation schemes.

Public Access Defibrillation describes the use of AEDs by members of the public. AEDs have been provided in many public locations by the Department of Health, the British Heart Foundation (BHF) and other charities and can now be found in many busy public places including airports, mainline railway stations, shopping centres, and gyms. They are meant to be used by members of the public if they witness a cardiac arrest.

The RC (UK) has designed a sign which many public spaces equipped with a PAD will display. If you witness someone who has collapsed possibly because of cardiac arrest, dial 999 to call the emergency medical services immediately. Follow the instructions given by the ambulance control centre who will provide instructions about the steps to be taken. This may include the location of the nearest PAD. Staff working at the location should also know the location of an AED nearby.

AEDs have been used by untrained people to save life. Clear, spoken instructions and visual illustrations guide users through the process. Lack of training (or recent refresher training) should not be a barrier to someone using one. If you are prepared to use the AED do not be inhibited from doing so.

There are first aid courses that include training on the use of an AED. The first aid organisations (for example St John Ambulance, St Andrew's Ambulance, The British Red Cross and The Royal Life Saving Society) provide training as do many independent private training companies.

Yes, it is usually safe to use an AED on a victim who is lying on a metallic, wet or other conductive surface. If the self-adhesive pads are applied correctly, and provided there's no direct contact between the user and the victim when the shock is delivered, there is no direct pathway that electricity can take that would cause the user to experience a shock. If the victim is wet, his/her chest should be dried so that the self-adhesive AED pads will stick properly.

The incidence of shockable rhythms requiring defibrillation in the paediatric population is very low but can occur. The priority must always be for high quality CPR and getting expert help. However, the AED can be deployed across all age groups if this is the only available machine.

The paediatric advanced life support guidelines 2015 state that if using an AED on a child of less than eight years, a paediatric attenuated shock energy should be used if possible. Commonly the AED will then restrict the shock energy to around 50 J. If the machine is sited in a school, a device or ability to attenuate the energy level should be available and training should be provided in the machine's use and users should always refer to the manufacturers guidance when writing local user guides.

Experience with the use of AEDs (preferably with dose attenuator) in children younger than 1 year is limited. The use of and AED is acceptable if no other option is available as on balance it is probably better to give a 50 J shock than nothing at all – the upper safe limit for dosage in this group is unknown.

Yes. Fortunately cardiac arrest is rare in women who are pregnant, but if it were to occur it is quite appropriate to use an AED. The procedure is the same as in the non-pregnant but it is important to place the pads clear of enlarged breasts.

Fortunately, sudden cardiac arrest (SCA) in school-age children is rare. Resuscitation attempts at schools are more likely to be made on an adult (staff member or visitor) than a pupil. The presence of an AED at a school therefore provides potential benefit for everyone present at the site.

An additional and important advantage of having an AED prominently located at a school is that students become familiar with them and can learn about first aid, resuscitation and the purpose of defibrillation.

The Department of Education has issued guidance about the installation of AEDs in schools.

If you think an AED should be installed in your workplace, read the Guide to AEDs written by the RC (UK) and the BHF as this will answer your questions in detail. If you wish to proceed, contact your local ambulance service for further advice as described in the Guide.