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Avoid electrical accidents due to unsuitable voltage test technology!

89.4% of electrical accidents occur in the low-voltage range. Of these, around 35% are attributable to the points "Switching off the voltage" and "Determining the absence of voltage". (Source: BG ETEM).

Unfortunately, the reason for this is still often the use of unsuitable test equipment, commonly known as classic "phase testers".


Notwithstanding the still valid regulation that the absence of voltage must be determined with a two-pole voltage tester, modern non-contact voltage testers offer a far higher level of safety and reliability than the traditional phase testers.

Why it is better to keep your hands off classic phase testers:

Their functional principle dates back to the 30s and is based on touching the live conductor with the metallic blade. A certain current then flows through the user's body via a series resistor, which causes the glow lamp built into the handle to light up.

Unfortunately, this simple measuring principle has several significant disadvantages. The biggest and at the same time most dangerous of these is certainly the fact that the user himself must be reasonably well earthed for there to be enough current flow at all and thus for the glow lamp to light up.

If, on the other hand, the user is electrically well insulated, the current flow is usually barely sufficient to make the glow lamp light up. The result: despite the presence of voltage, it is wrongly assumed that there is no voltage; an electrical accident is practically pre-programmed!

Conventional phase testers are unsuitable for humid environments and non-grounded IT networks.

Due to the technical design, phase testers may only be used in dry environments for safety reasons. Otherwise there is a risk of accidents due to moisture penetration. If you are dealing with a power supply system that is not earthed for operation, the phase tester will also fail completely.

Employers must provide their employees with suitable and safe equipment.

Besides the technical shortcomings mentioned above of the "phase testers", which are no longer up to date, liability problems are also likely to arise if property damage or even personal injury occurs due to unsuitable tools and measuring devices.

Modern non-contact voltage testers work far more reliably and safely!

For some time now, there have been considerably better alternatives to the classic phase tester, namely single-pole contactless voltage testers, often also referred to as "NCV testers". These voltage testers no longer require direct electrical contact with the live conductor but detect alternating electrical fields without contact via an electronic sensor system.

If a live line is detected, they signal this clearly visually via a bright LED signal and optionally acoustically by means of a signal transmitter. Since direct contact with the conductor is no longer necessary, insulated lines and cables can also be tested without any problems. This is particularly helpful, for example, when it is necessary to detect a conductor break. Simply moving the voltage tester along the active line is sufficient for this: At the moment the signal ends, the electrical break is directly in the area of the test probe.

The operation of a contactless voltage tester is very simple and basically leaves no room for operating errors. When switched on by pressing the button, the NCV tester runs through a short self-diagnosis and the acoustic signal generator is briefly activated to be able to check its function. The indicator light shows that the voltage tester is active. Before starting work, the tester should always be held briefly against a live line to ensure that it is working correctly.

Individual performance features of contactless voltage testers vary depending on the manufacturer and design.

Basic models offer only basic functionality - they light up and beep when held near a live line. Voltage testers from Klein Tools, which have two switchable sensitivity ranges, are much more convenient. On the one hand, they detect AC voltages from 12 volts AC, but on the other hand, they also allow for a better assignment of individual conductors if there are other lines in the vicinity.

Versions that additionally convert the strength of the electromagnetic alternating field via varying light and sound signals are particularly practical. This makes it significantly easier to locate live conductors quickly and to assign them precisely. A switchable torch function makes working in poorly lit environments easier and safer, eliminating the need to carry an additional light source.

Higher-quality models offer further additional functions.

Versions are now available on the market that integrate a laser distance meter or a contactless infrared thermometer in the compact housing of a voltage tester. This makes it unnecessary in many cases to purchase these measuring devices, which are often needed by electricians, separately and to carry them with them at all times.

For all measurements, there is also the advantage that the design of contactless voltage testers helps to avoid accidents and damage. Their housing is made entirely of non-conductive material, so accidental short circuits and arcs of stray light cannot be triggered with them.

Likewise, a high measurement category - CAT IV up to 1000 volts for the models presented here - ensures appropriate safety for the user when working on all equipment included here.

Conclusion: Today, there are no longer any reasonable reasons to use very antiquated and, in many cases, potentially dangerous testing equipment. Modern non-contact voltage testers are clearly superior to their predecessors with single-pole metallic test probes in all respects. Their low purchase price (starting at around 20 euros for entry-level models) makes them affordable for everyone, even for hobbyists. For electricians and all service technicians, they are indispensable tools that are indispensable in daily practice.

Its limits are only in the case of very densely packed cable bundles and so-called open or reactive voltages, as they can arise through capacitive or inductive coupling of neighbouring, voltage-carrying cables. However, it should be noted that such reactive voltages are also reliably detected and signalled. By using a two-pole voltage tester with switchable load, a reliable assessment must be made as to whether the reactive voltage is harmless or whether a dangerous voltage is present. 

Combined models with integrated IR thermometer or laser distance measuring function can often replace corresponding separate measuring devices. They save space and are always quickly at hand when needed.

Due to the enormously simple, basically self-explanatory operation of contactless voltage testers and their extensive safety against incorrect use, "overlooking" live cables and system parts is practically no longer possible. An integrated self-test function also ensures that you are always working with a correctly functioning tester.

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