Residual Current Device (RCD) Protection – Provided & Tested?


Portable electrical equipment is not used outside without RCD protection.

Reason for This Question

All portable appliances should only be used outside with RCD.

Possible Answers

Red: Evidence of portable equipment being used outside without RCD protection and/or no PAT test records
Green: Any equipment intended for use externally is RCD protected

Common Issues

  • No RCD protection devices provided within the premises.
  • Portable electrical appliances in the premises have not been subjected to a PAT test.
  • No PAT testing records or certificate available.
  • Items in use had not been tested.

Fail Rate

27% of businesses failed this question based on our sample data.


What Is Portable Appliance Testing (PAT)?

Simply put, Portable Appliance Testing refers to the process of determining whether an electronic appliance is safe and fit for use.

The use of electrical appliances is widespread in today’s modern age. Different professionals and workers use portable appliances when working on projects.

The use of electronic appliances comes with an associated risk of injury. To minimise the level of risk associated with the use of electrical appliances, it’s important to keep them in the best working condition.

Portable Appliance Testing (PAT) provides duty holders, including employers and self employed professionals, with a means of ensuring that their appliances are in perfect working order.

The first step in this process involves carrying out a visual inspection of the appliance, with focus on the plug, cable and appliance body. The second part of the process involves testing the appliances’ polarity, earth continuity and its insulation.

This inspection should be conducted by a qualified expert. This ensures that they conduct the testing in line with the necessary safety requirements, without exposing themselves or others to any risks.

Once an appliance undergoes PAT, and is found to be safe and fit for use; it is labelled with a PAT sticker. The sticker has the word PASS on it, indicating that the appliance passed the test requirements. The sticker also indicates the recommended re-test date for the appliance; acting as a reminder to both users and owners.

Appliances that fall short of the test requirements are usually labelled with a FAIL sticker. These should not be used in their current condition, and should be repaired or disposed off responsibly.

Is PAT Testing A Legal Requirement?

The most confusing issue when it comes to PAT revolves around the question whether it is a legal requirement. Just to clarify, PAT is not expressly provided for under any law. This means that it is not a legal requirement.

It is however useful when it comes to helping duty holders comply with any laws relating to the maintenance and use of portable electronic appliances.

As per the provisions of the Electricity at Work Regulations 1989, electronic appliances that have the potential to cause injury should be maintained in the best possible condition. It is however worth noting that the law does not specify how this should be done, and who should do it.

PAT testing is one of the ways duty holders comply with the provisions of the above law.

The HSE (Health and Safety Executive) provides guidelines on how PAT testing should be conducted. Some of the main aspects it touches on include the recommended frequency of PAT testing. According to the HSE, duty holders should conduct a risk assessment of their operations to determine how often they should test their appliances.

From the above, we can clearly see that PAT, though not legally required, provides duty holders a means of ensuring that they maintain electronic appliances that are fit for use, at all times.

What Is a Residual Current Device (RCD)?

A residual current device, commonly abbreviated as RCD, is one that causes a break in a current carrying circuit with the aim of preventing any further injury in the event of an electric shock. Its name, however, varies from region to region. In the UK, RCD is the more common abbreviation, and an RCD and MCB (miniature circuit breaker), the combination is collectively referred to as an RCBO (residual current circuit breaker with overcurrent protection). Further south in Australia, they also go by the initials RCD or known singularly as a safety switch.

RCDs are designed to instantly and automatically break a circuit when an imbalance between the live conductors and the neutral conductor is detected. Under everyday circumstances, the live and neutral wires are required to conduct the same levels of current. A difference in these two levels could be due to a short circuit or any other fault, such as a leakage. Leakages could be indications of shock hazards or shocks in progress. A current of approximately 30mA holds the capability to cause a heart attack if allowed to go on for more than a few fractions of a second. RCDs are therefore necessary to quickly disconnect the conductors, reducing further harm brought about by shocks.

An RCD does not, however, guarantee safety from dangerously high or unexpected currents, commonly referred to as spikes or surges, when current goes through the usual wires within the circuit. It is for this reason that it is incapable of replacing a fuse, or safeguarding against fire risk as a result of overloads or short circuits if there is no leakage of current.

In order to reduce shock risk, it is recommended that RCDs react within 30 milliseconds of any leakage greater than 30mA bring detected. They operate by calculating the current levels between two wires by use of a current transformer, which calculates the differences in current flowing through the live wire and that through the neutral wire. If the difference is not equivalent to zero, then that would indicate the presence of a leak, which would subsequently cause the RCD to open its contacts.

The existence of a fault current is not required for the RCD to operate. Automatic disconnection, as well as a degree of shock prevention, is therefore still guaranteed even if the installations earth wiring is incomplete or damaged.

It is sometimes common to have electrical plugs that have RCDs incorporated into them, installed into appliances that may pose significant safety hazards. Examples of this equipment may include gardening equipment or others that hold a greater chance of interacting with water or any other liquids.

By placing RCD in an extension lead, protection is ascertained at all times, regardless of whether the building has old wiring or wiring with no grounding conductor.

Residual current detection works alongside over current detection. It is not sufficient for guarding against overloads or short circuits. There are regulations which govern the required standards and all the equipment must meet certain requirements for approval to be used commercially.

This post is part of the “Focus on Health and Safety Audit Questions” series. A series which focuses on questions asked by our health and safety consultants when conducting a health and safety audit.