What Is RCD Testing and How Is It Different from Test & Tag?

RCD testing checks the safety switch itself via a push-button test and a precise trip-time measurement, while test & tag checks individual appliances and leads. Both are required in NSW workplaces, cover different risks, and aren’t automatically included in one another.

Introduction

You’ve had your workplace tested and tagged. Every lead, power board, and appliance has its tag showing a pass and a retest date, and you’ve filed the compliance report away for your next audit. Then someone—an insurer, a WHS consultant, a new hire who used to work in facilities—asks whether your RCDs have been tested, and you realise you’re not sure if that’s a separate job or something your test & tag provider already covered.

It’s a fair question, because the two services get bundled together so often in marketing that the line between them blurs. They’re not interchangeable, though, and understanding the difference matters more than it might seem: one protects your appliances, and the other protects the people using them.

What Does an RCD Do?

RCD stands for residual current device, though you’ve almost certainly heard it called a safety switch. You’ll find one in your switchboard, and sometimes as a standalone portable unit plugged into an extension lead or power board on site.

An RCD’s job is to watch the electricity flowing through a circuit and compare what goes out against what comes back. Under normal conditions, those two figures match. If a fault sends current somewhere it shouldn’t—through a person, for instance, rather than back along the wiring—the RCD detects that imbalance and cuts the power. The whole process happens in a fraction of a second, fast enough in a properly functioning device to prevent a fatal shock.

What Is the Purpose of Test & Tag?

Test & tag looks at your equipment:

• the toaster in the staff kitchen,
• the laptop charger under someone’s desk,
• the extension lead running to the printer.

A technician inspects each item for damage, then runs electrical tests:

• insulation
• resistance,
• earth continuity, and
• leakage current

… to confirm the equipment itself is safe to plug in and use.

• Pass, and it gets a tag with a retest date.
• Fail, and it gets pulled from service.

None of that tells you anything about whether the safety switch behind those power points would trip if one of those appliances developed a fault tomorrow. That’s what RCD testing is for.

Push-Button & Trip Time RCD Tests

RCD testing under AS/NZS 3760:2022 involves two separate checks, and mixing them up is where a lot of businesses end up with a false sense of security.

Push-Button Test

The push-button test is the one most people are familiar with because of the “T” or “Test” button on your switchboard or portable RCD. Press it, and it simulates a fault, which should cause the device to trip. This confirms the mechanism moves. It’s quick, anyone on site can do it, and it belongs in a regular routine, daily for portable RCDs before use, and typically monthly for fixed RCDs installed in your switchboard.

Trip Time Test

The trip time test, also called an operating time test, is a different exercise altogether. A technician uses specialised equipment to inject a small fault current into the circuit and measure precisely how many milliseconds the RCD takes to respond. Under AS/NZS 3760:2022,

• a standard 30mA RCD (Type II) has to trip within 300 milliseconds, while
• a more sensitive 10mA RCD (Type I) has to trip within 40 milliseconds.

This test needs proper instrumentation and a competent tester, so it’s carried out at a scheduled interval rather than by an occupant.

Difference

An RCD can pass a push-button test every day for a year while still being dangerously slow to react to an actual fault. The button confirms the spring moves. It says nothing about the speed. A device that trips in 400 milliseconds instead of 300 will still flick off when you press the button, but that extra 100 milliseconds can be the difference between a close call and a serious injury. Trip time testing is the only way to catch that.

RCD Testing Frequency Requirements

AS/NZS 3760:2022 sets intervals based on how your RCD is used and where:

Under the Work Health and Safety Regulation 2017, the person or business in control of a workplace (the duty holder) has to make sure electrical equipment, RCDs included, is maintained so it’s safe to use. That obligation doesn’t ease off because your test & tag is current. They’re two separate items on the same compliance checklist, and an auditor, insurer, or WHS inspector will look for both.

Importance of RCD Testing for Businesses

If you’ve assumed your test & tag service already covers your RCDs, it’s worth checking rather than guessing.

• Some providers include RCD testing as standard,
• others treat it as an add-on, and
• a few don’t offer it at all.

None of that is obvious from a report that says “all items passed” unless RCDs were specifically part of the scope.

The stakes here are higher than a failed appliance. A dodgy toaster gets pulled from service and replaced. A slow or non-functioning RCD sits invisibly behind your switchboard, doing nothing until the day someone needs it to work, and by then it’s too late to find out it wouldn’t have.

Get RCD and Test & Tag Done Properly

At Success Works, we test both fixed RCDs in your main switchboard and any portable RCDs on site, measuring actual trip time rather than relying on a push-button check, alongside our test & tag service. You get

• one visit,
• one digital report covering your appliances and your RCDs, and
• a reminder before either is due again.

Every technician on our team is a woman who’s faced barriers to employment before being trained and given genuine work through Success Works. Booking your electrical compliance with us means your workplace gets it done properly, and your spend supports something meaningful. If you’re not sure whether your RCDs have ever been trip-time tested, book a site visit and we’ll find out for you.