For any electrician, a digital multimeter would rank as one of the most important items they have in their tool kit, provide a large degree of functionality and enabling them to quickly pinpoint what is happening within an electrical system.
Arguably the most important function a digital multimeter provides is the ability to work out the absence of voltage, which is the most important step an electrician can take to make sure of their own safety.
However, this does not mean that digital multimeters do not come with their own set of dangers, though the good news is there are ways to avoid those risks.
Avoid misusing a digital multimeter
One of the biggest dangers in regards to digital multimeters is actually when they are misused. Trying to measure the voltage when the test probes of the model are still in the current terminals is usually an accidental occurrence, but can be potentially very dangerous and though protection is offered by the DMMs fuse, it is not absolute.
The design of those current terminals is something else that needs to be taken into consideration when using a digital multimeter. They perform measurements within the low energy circuits by having the meter implanted in series after opening the circuit.
A digital multimeter’s ammeter function needs low input impedance, with between 0.1 and 10 ohms being the typical values, because otherwise the current in the circuit being measured could actually be reduced by the gadget itself.
The low impedance of the circuit actually makes it very vulnerable with the DMM serving as a branch circuit that the user is actually holding in their hand, why is why it needs to be protected by high energy fuses.
In the event that these fuses blow, they should only be replaced with those specified by the DMM manufacturer.
The device being used in the wrong power category is also very dangerous, as it is highly likely to result in a power surge all across the fuse that has been destroyed.
The measuring of resistance is something else that also commonly results in the digital multimeter being misused, with an individual often making contact with a live circuit that they thought was dead.
Happily, the majority of modern DMMs feature terrific overload protection and automatic recovery thanks to a thermistor being implanted in the ohms circuit, which causes a rapid increase in resistance from an overloaded circuit along with the heat. This protection is however no excuse for reckless behaviour.
Important safety precautions for digital multimeters
A visual inspection of a digital multimeter should always be undertaken prior to use. The accessories, meter and test probes should be examined for damage, plugs to ensure they still fit securely and an eye kept out for any casing cracks or exposed metal. A digital multimeter with any kind of damage should never be used.
The multimeter should then be checked to ensure it is working in the correct manner.
There are always dangers when working with electricity, but being aware of the hazards and taking precautions when using a digital multimeter should help to avoid accidents.