Earth Bond Continuity Test
As you just heard in the video, you can see the clear differences between the different standards below, taking note of the big difference when it comes to leads. This is good time to mention that you should check your tester to make sure it is correctly set up for testing medical equipment. For the Alpha PAT and Metro iPAT we have designed specific test codes. If your tester isn’t correctly set up for medical testing, we strongly advise you to give us a call on 0800 638 768.
Limit AS/NZS 3760
| IT | 1.0Ω | 100/200mA |
| Leads | 1.0Ω | 10A |
| Leads & High Current draw devices | 1.0Ω | 25A |
Limit AS/NZS 3551
| With Non-Detachable Lead | 0.200Ω | 100/200mA |
| Appliance inlet with no lead fitted | 0.100Ω | 100/200mA |
| Lead | 0.200Ω | 10A (recommend best practice) |
The Procedure:
An Earth bond continuity test should be performed after a visual inspection, especially if it is a class I piece of equipment. Please read through the following procedure even if you are aware of how to perform an Earth bond continuity test to make sure you are doing it correctly.
a) Plug the equipment to be tested into the Metrel AlphaPAT/MetroiPAT Portable Appliance Tester.
(Please note these testers are not solely designed as medical testers but when set up correctly and used with appropriate/necessary accessories, they can be used to perform tests to medical standards. These two testers are often preferred (but not the only choice) when it comes to performing medical tests in accordance with the AS/NZS3551 and will be referred to often throughout the course.
b) Hold the “earth wander” lead to a metal part of the equipment.
c) Select from the main menu – ‘AUTOTEST (CODES)’.
d) Select the desired code or Auto Test (Codes) by using the touch screen or entering a 3-digit code.
e) It is recommended that earth testing be performed at a test current of 10 Amps, this proves that the protective earth has been tested in a real-life scenario.
(we recommend the low current earth test of 200milliamps for computer equipment and the likes of other medical equipment)
f) Follow the onscreen prompts to complete the test.
g) Take a representative sample of exposed metal parts. If ‘FAIL’, then first ensure the appliance under test is plugged in and that
the correct appliance is also plugged in. (ensure the wander lead is plugged into the correct socket)
You may have wondered about that last part; ‘representative sample’. Simply this means you must perform an Earth bond continuity test 3 times at 3 different places. If you have only been performing 1 Earth bond test, then you have been doing it incorrectly.
h) Follow tester prompts and retry the test holding the clip on to another piece of bare metal (a screw or bolt is always a good option). If test again fails the appliance will be faulty – DO NOT PROCEED.
i) If a ‘PASS’ then proceed to the next test.