Published : 07/25/2017 10:24:59
Categories : Mister Worker , Professional working tools guide

Are you looking for a precision instrument to take various electrical measurements? On the market there are several testers that perform these operations, each with different characteristics and potential: some testers are therefore more professional than others, depending on the needs of the individual, given that an electrician certainly has different needs than a hobbyist.

In descending order of functionality we find: multimeter, current clamp and test screwdriver. In reality, the latter does not detect intensity, but only wether a specific point in the circuit has voltage or not. But let's go in order and analyze every tool in detail.


The multimeter, often called a multi-tester, is able to measure numerous quantities. For example, the highly professional USAG multimeters measure voltage, resistance, both alternating and continuous current flow, temperature, and they also perform diode test. The multimeters can be analog or digital: the analog multimeter is the oldest model and allows a slightly inaccurate measurement, while the digital multimeter has the advantage of presenting a clear and easily readable indication; thanks to this tool, it is therefore possible to exclude errors due to incorrect calculations of measuring ranges or reading errors.


In order to use a multimeter you, first of all, need to set the quantity to be measured using the selector. Then you have to set the full scale value, which must be higher than the value you are going to select, otherwise the multimeter will not be able to measure.

If you are using an analog multimeter, you must make some calculations after the measurement. For example, if you selected the 220 Volt scale (the measure of the electrical voltage in our houses) and get 0.56, you have to multiply these two values together to get the actual value of the electric voltage.

In the case of a digital multimeter this is not necessary, because the displayed result is already the actual one. Using the FACOM professional digital multimeters you don’t even need to set the scale, as it is possible to set the range (full scale value) either manually or automatically, so it will be the multimeter the one that identifies the most suitable scale of values.

Given the large number of uses allowed, the multimeter is a very often used work tool not only by electricians but also by electrical experts, electronic experts and electronic designers. For example, in order to know how much current an appliance absorbs (if this value is no longer visible on the appliance itself), replace cables and resistors, make the electrical continuity test (ie check if a component allows more or less current to flow), check the resistance value of a resistor when the color code is not clearly visible, measure the input or output resistance of a circuit, verify the operation of a sensor or potentiometer, test electrical circuits and other necessary activities to adjust or build basic electrical or electronic systems.


Since measuring resistance is very often necessary, I would like to suggest some measures for a correct and precise measurement. First of all, the resistance measurement must be carried out before the component is inserted into the circuit, otherwise it will end up measuring everything that is connected to the resistor. Furthermore, the component must not be powered. The multimeter, in fact, evaluates the amount of current flowing in the component and will translate the whole into a resistance value therefore, if the component is powered, the resistance value detected will be wrong.

Considering how many problems can be solved thanks to a multimeter, my advice is to always have a good quality one available, whether you have a workshop or not. In fact, the higher the quality, the greater will the ease of use and the measurable quantities also be.


After talking to you about the multimeter, let's move on to another tool used for measuring electrical current: the current clamps.

The current clamp measures only the amps "A", (unit of measure of the electric current) and, unlike the multimeter, it is used to measure the passage of current in any cable, also welded, without needing to access the poles (as for the multimeter) and disconnect the system. This is very useful in cases where it is very difficult to get to the poles of the electric circuit or in the presence of systems that need to be constantly under tension. In short, it means that it can also be used when it is not possible to de-energize a system, so as not to interrupt the operation of special machinery, as in the case of factories or hospitals. In fact, the only necessary condition is that the cable passes through the jaws of the clamp.

Also remember that to use this kind of clamp you need to connect it through the two pins to a digital multimeter, making sure to respect the polarity, in order not to have false values. However, if desired, it is also possible to buy an integrated caliper and multimeter.

Even though the current clamp is not a very used tool, it is a very useful tool, as it allows to know with confidence and precision the real absorption of any electrical device and of how much current passes from one or more cables.


Finally, I want to talk about another tool that can detect the presence of voltage: the screwdriver.

Very useful in case you need to do simple tests in AC circuits where it is not necessary to know the precise value but only if voltage is present, the tester screwdriver is the most suitable tool. In the shape of a screwdriver (in fact it can also be used as such), it is generally used to trace the phase cable or to detect anomalies between the conducting wires; for example, if the phase finder reacts to contact with the earth cable (in the electricity distribution system in Italy we are always in the presence of a phase cable, a neutral one and a ground cable, usually in a central position) would mean that we are in the presence of a serious anomaly in the electrical system!


The phaser is used by placing the tip of the screwdriver on a point in the circuit and pressing the thumb at the end of the handle. Inside the instrument there is a light bulb connected to a resistor, which will light up in contact with a live component. Touching the metal terminal, we are the ones closing the circuit to the ground and being run by a small current that allows the ignition of the light bulb.

In case you are thinking of buying a tester, USAG offers a very useful set of professional tools for electrical engineering, including universal insulated gripper, jig saw blade, a multi-purpose knife with sector blade, a 110 to 380V phaser screwdriver, a hammer with a handle made of wood, a flexometer with an ABS case, a scissors for electricians, two insulated screwdrivers for slotted screws, two Phillips insulated screwdrivers and a tool box. This range is ideal for performing any basic electrical engineering repair!

In summary, there are several tools that can be used to check electrical components. However, there is no best choice because it all depends on individual needs. In any case, having to do with electricity, it is very important to always use quality products, such as USAG tools, to prevent the instrument you are using from breaking down immediately or causing damage to yourself.

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