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How to use a Megger to Identify a Faulty Element

An Insulation tester like a megger can show a component failing that a normal multimeter would not show. Here is how to use this useful tester on heating elements.

Video Transcript

Hi I'm Mat from eSpares.

In this video I will be showing you how to use a megger or insulation tester to help identify problems in a domestic appliance.

Now although a megger or insulation testers are not commonplace in most people's toolboxes, it may be possible to access one, either through some installation work taking place in your home or by borrowing one from a friend or neighbour.

As they are so useful we thought we would do a brief video to show you how best to use them.

Unlike a normal multimeter, insulation testers use a much higher voltage to test for a resistance leak. If I press the test button here you can see that the meter attached to the megger is giving a reading well over 500 volts, whereas a multimeter would typically use nine volts to measure.

Therefore a megger is more likely to show a failing element that is tripping the fuse board.

Safety first: always unplug an appliance before carrying out any work.

The next thing you need to do is to isolate the component that you want to test.

What I have in front of me is a range of elements. We have a grill element, a dishwasher element, two washing machine elements and a fan oven element.

To test these components grab your two probes, and what I'll do is start with a washing machine element that I know is good and new and shouldn't show any faults.

Attach one probe to the metalwork of the component and the second to the electrical connector on the element and press test.

Now the reading I am getting here is over a thousand Meg ohms therefore there is no resistance within the component and the component is fine.

If I do the same test on the fan oven element again connecting one probe to the metalwork and the other to the electrical connector and pressed test once more you can see a reading of 7.6 Meg ohms.

If you have a reading of less than 2 Meg ohms, it will mean that the component is very likely to be tripping your electrical board at home.

Whereas this one has a reading of less than thousand Meg ohms but not as low is two Meg ohms it means that although there is a fault in this component given time it may develop into something that does trip you're electrical board.

So if your extra component has a reading similar to this and it is tripping the fuse board in your home is likely that the electrical component needs replacing.

Although this is a very brief explanation of how meggers or insulation testers work, we hope that this can be of use to you to find a fault in your domestic appliances in your own home.

It is worth noting that although the megger has a high voltage output, the current is very low therefore in the unlikely event that you do get a shock from a megger it will be similar to touching an electric fence.

Remember spares and accessories for most appliances can be found on the eSpares website.

Thanks for watching.

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