If you’ve ever watched a Residual Current Device (RCD) being tested, you’ll know the test is over in less than a second. But that fraction of a second is everything — and AS/NZS 3760:2022 is very specific about exactly how fast an RCD must respond in the event of an incident.
Here’s what the standard requires for RCD’s located in your switchboard or GPO, what it means in practice, and what to do if your RCD doesn’t pass. You can also review the state specific regulations on RCD testing on our state specific regulations pages for more information specific to your workplace.
The Short Answer
| TYPE 1 FIXED RCD | Must trip within 40 milliseconds (0.04 seconds) at a test current of 10mA a.c. |
| TYPE 2 FIXED RCD | Must trip within 300 milliseconds (0.3 seconds) at a test current of 30mA a.c. |
These are the maximum allowable trip times specified in AS/NZS 3760:2022. A RCD that takes longer than these limits to trip is non-compliant and must be taken out of service.
Type 1 vs Type 2 RCDs — What’s the Difference?
Not all RCDs are the same. AS/NZS 3760:2022 distinguishes between two types based on their sensitivity and the protection they provide:
| RCD Type | Test Current | Max Trip Time | Typical Use |
| Type 1 | 10mA a.c. | 40 milliseconds (0.04s) | Body contact protection — highest sensitivity |
| Type 2 | 30mA a.c. | 300 milliseconds (0.3s) | General circuit protection — most common in Australian workplaces |
Type 2 RCDs (30mA) are the most common type found in Australian workplaces. They provide protection against the most significant electrical shock risks and are suitable for protecting portable electrical equipment in most environments.
Type 1 RCDs (10mA) are higher-sensitivity devices used in environments where there is a greater risk of direct body contact — such as some healthcare settings or portable equipment used in particularly hazardous conditions. They are less common in standard workplace applications.
Why Do RCD Trip Times Matter?
The trip time is the difference between a RCD that saves a life and one that doesn’t. Here’s why the milliseconds matter:
The human body can tolerate very small currents for short periods. At 30mA, ventricular fibrillation (cardiac arrest) can occur if current flows for more than approximately 300–500 milliseconds. This is why the 300ms maximum for a Type 2 RCD is not arbitrary — it’s set at the threshold below which serious cardiac injury is unlikely to occur.
An RCD that trips in 280ms is compliant. A RCD that trips in 350ms is not — and in the event of a fault, that 50 millisecond difference could be the difference between a near-miss and a fatality.
This is also why regular testing matters. A RCD that tripped correctly 12 months ago may not do so today. Mechanical components age, contacts oxidise, and the trip mechanism can degrade over time — often without any visible sign of a problem.
What Happens During a RCD Trip Time Test?
An ATS technician uses a calibrated RCD tester (also called a PAT with RCD test function, or a dedicated RCD testing instrument) to simulate a fault current and measure the exact time the RCD takes to trip.
The test process:
- The instrument is connected to the circuit protected by the RCD
- A simulated fault current (10mA for Type 1, 30mA for Type 2) is injected into the circuit
- The instrument measures the time between fault injection and RCD trip, in milliseconds
- The result is recorded as a PASS (within the allowable trip time) or FAIL (outside the allowable limit)
- The RCD is also manually operated using its push-button to verify the mechanism functions correctly
All results are recorded digitally in the ATS AIM portal, creating a timestamped compliance record for each RCD tested. ATS technicians do not complete any live testing at a switchboard.
What If an RCD Fails Its Trip Time Test?
A failed RCD must be taken out of service immediately. Under AS/NZS 3760:2022 and WHS Regulations, a RCD that does not trip within the required time cannot be used to protect a circuit.
What typically happens:
- The ATS technician tags the RCD as FAILED and documents the result in your compliance records
- The failed RCD should be replaced or repaired by a licensed electrician before the circuit is returned to service
- ATS can advise on next steps and, where we have arrangements with electrical contractors in your area, can help coordinate a repair referral
IMPORTANT – Do not simply reset and continue using a failed RCD. A trip time failure is a real defect — not a test anomaly. The RCD will not provide the protection it is required to provide.
How Often Should RCDs Be Tested?
AS/NZS 3760:2022 specifies testing frequency based on the environment. Push-button testing (a simple self-test you can perform yourself) and instrument testing (the calibrated trip-time test performed by a competent person) have different schedules:
| Environment | Fixed RCD Type | Recommended Testing Frequency |
| Construction / demolition sites | All types | Monthly (push-button) + 3-monthly (instrument test) |
| Hostile environments (workshops, kitchens, factories) | Type 2 | 6-monthly (push-button) + 12-monthly (instrument test) |
| General workplaces (offices, retail, healthcare) | Type 2 | 6-monthly (push-button) + 12-monthly (instrument test) |
| Residential (where tested under AS/NZS 3760) | Type 2 | 6-monthly (push-button) + 2-yearly (instrument test) |
NOTE – Push-button testing confirms the mechanism functions — it does not measure trip time. Instrument testing by a competent person is required to verify compliance with the trip time limits in AS/NZS 3760:2022.
Fixed RCDs vs Portable RCDs — Does This Apply to Both?
Yes. AS/NZS 3760:2022 applies to both fixed RCDs (installed in the switchboard) and portable RCDs (plug-in safety switches used with portable equipment). Both types must meet trip time requirements and both must be tested at the required intervals. In most environments, Portable RCD’s are required to be trip time tested every 6 months, and push-button tested 3 monthly.
Portable RCDs are particularly common on construction sites, where they provide protection for power tools and extension leads and have more stringent test requirements. They should be visually inspected before each use and instrument-tested at the required intervals — typically every 3 months on construction sites.
Need Your RCDs Tested?
ATS provides professional RCD testing services across Australia, using calibrated instruments and providing full digital records via the AIM portal. We test both fixed and portable RCDs, and can combine RCD testing with your test and tag service to reduce cost and minimise disruption.
- Calibrated instrument testing to AS/NZS 3760:2022
- Pass/fail results documented for every RCD
- Full digital compliance records via AIM portal
- Available as a standalone service or combined with test and tag
- Technicians available across Australia — metro and regional
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