Residual Current Devices are essential for electrical safety. Recent updates to the Wiring Rules have changed what's required. Here's a plain-English explanation.
Residual Current Devices (RCDs) are the safety switches that cut power almost instantly when they detect a fault. They're the reason a faulty appliance causes a tripped circuit rather than a fatality. In commercial buildings, getting RCD protection right is both a safety requirement and a compliance obligation.
The AS/NZS 3000 Wiring Rules set out the requirements for RCD protection, and they've been updated in recent years. Here's what matters for commercial buildings:
What the rules require
For non-residential premises, final sub-circuits up to 32A capacity supplying socket outlets must be protected by 30mA RCDs. Hard-wired equipment circuits of the same capacity should also be protected. All lighting final sub-circuits must be RCD protected.
Importantly, if you're altering a circuit configuration (not just doing a like-for-like repair), that alteration triggers the requirement for 30mA RCD protection on that circuit. And where all protection devices are replaced in a switchboard, all final sub-circuits must be RCD protected.
What this means in practice
If you're doing a fit-out or refurbishment that involves any electrical work, your electrician needs to assess whether the existing RCD protection meets current requirements. In older buildings, this is often where compliance gaps appear.
The good news is that upgrading RCD protection is generally straightforward when it's planned as part of a broader electrical scope. The problems arise when it's discovered late, or not discovered at all until an inspection.
A note on switchboard upgrades
When a switchboard is being replaced or significantly upgraded, it's the right time to ensure all circuits are properly protected. We always assess RCD requirements as part of any switchboard scope, and we document the outcome clearly.
If you have questions about your building's RCD compliance, or you're planning a fit-out and want to understand the electrical requirements upfront, we're happy to talk through it.
