RCD Protection Explained: Why Your Business Needs It

RCD Protection for Businesses

A Residual Current Device (RCD) is one of the most important electrical safety devices in any workplace. It can save lives by cutting the power in milliseconds when it detects a fault. Yet many businesses — especially those in older premises — do not have adequate RCD protection.

What is an RCD?

An RCD continuously monitors the balance of current flowing through the live and neutral conductors. In normal operation, these should be equal. If current is leaking to earth — through a person's body, through a fault in an appliance, or through damaged insulation — the RCD detects the imbalance and disconnects the supply within 30 milliseconds.

30 milliseconds is fast enough to prevent a lethal electric shock in most circumstances. Without an RCD, a fault could deliver a fatal shock for several seconds before a fuse eventually blows.

Types of RCD

• Consumer unit RCD: Protects all circuits (or a group of circuits) from the main distribution board
• Socket-outlet RCD: An RCD built into a single socket — useful for protecting specific high-risk locations
• Plug-in RCD: A portable RCD that plugs between an appliance and the socket — essential for outdoor use and construction sites

When RCD Protection is Required

• Outdoor use: All outdoor electrical supplies must be RCD protected
• Construction sites: All temporary electrical supplies on construction sites must have RCD protection
• New installations: Since the 17th Edition (2008) and 18th Edition (2018) of the Wiring Regulations, RCD protection is required on most circuits in new and rewired installations
• Best practice: Even in older installations without RCD protection, adding RCDs is strongly recommended

RCDs and PAT Testing

RCD protection and PAT testing work together as complementary safety measures. PAT testing identifies faulty equipment before it causes a problem. RCD protection provides a last line of defence if a fault develops between tests. Neither replaces the other — you need both.

Does Your Business Have RCD Protection?

Check your distribution board. Modern consumer units have RCDs integrated. Older boards may not. If you are unsure, ask a qualified electrician to check. For PAT testing across Greater Manchester and Northwest England, contact Green Tag PAT.