Two-pole voltage testers

Why do you need a two-pole voltage tester?

When you are dealing with two-pole voltage testers, questions often arise such as:

• Why should I use a two-pole voltage tester at all?
• Is my single-pole tester not sufficient?
• I can also determine the absence of voltage with a multimeter! 

Every electronics technician working in Germany, Austria and Switzerland, for example, learns the rules for safe working during electrical installation during their training. The following is also learnt in this context:

The two-pole voltage tester is the only device authorised to detect the absence of voltage in low-voltage systems. (Safety rule three of the "Five Safety Rules" for electricians.)

This is specified in DIN EN 61243-3 VDE 0682-401. According to this standard, the absence of voltage on all poles must be determined using a suitable test device before installation work is carried out. This means on each individual conductor. Therefore, single-pole testing devices such as a conventional screwdriver-type voltage tester are not suitable. Because they only test single-pole.

Finally, the user uses a two-pole voltage tester to check whether there is any residual voltage or whether he has inadvertently disconnected the wrong cable. On the one hand, this protects the user from electric shocks. On the other hand, the test protects against material damage and thus also against claims for damages in the commercial sector.

Why is it not permitted to determine the absence of voltage with a multimeter?

Even if a multimeter is designed for two-pole voltage testing, it is not approved for detecting the absence of voltage. This is mainly for the following reasons:

1. The multimeter must be set to the correct measurement type (volts, amps, ohms...) before the measurement. Application errors can occur. For example, because DC voltage is selected as the measurement type but AC voltage is present. Or the device is prepared for current measurement but then used for voltage measurement, which leads to a short circuit.
2. A multimeter can only measure with a charged battery. However, it must also be possible to detect the absence of voltage when the batteries are discharged. This is only possible with the two-pole voltage tester.
3. Finally, there is another practical reason in favour of the two-pole voltage tester: A multimeter with the housing and two test leads is more unwieldy because the "third hand" is missing. The two-pole voltage tester with two insulated handles can be operated comfortably with two hands and, depending on the equipment, even with one hand. 

To summarise, your safety should be the top priority during work. The use of a two-pole voltage tester is the safest way to determine the absence of voltage. That is why only it is authorised for this purpose!

Measuring range and measuring category for voltage testing

Measuring range
Especially if you are a DIY enthusiast, you should think about which voltage levels you mainly want to measure before purchasing a two-pole voltage tester. The larger the measuring range that you can measure with your voltage tester, the more versatile you can use the device. However, a large measuring range is usually associated with a higher purchase price. It is unnecessary to buy a high-end device that measures voltage levels that you will never need. You will probably need the device in your own home for simple test procedures, for example to check a socket outlet up to 230 V AC. And if you also want to test your car battery from time to time, you need a device that can measure 6 - 12 volts DC.

Of course, the measuring range is also the decisive factor in the professional sector before deciding in favour of one or the other two-pole voltage tester. The widest possible scale is therefore essential. Because you can then use your two-pole voltage tester in a variety of ways. As a professional, you can work with these measuring ranges, for example:

• Applications in the switch cabinet > 24 V AC voltage as well as 10 and 24 V DC voltage
• Applications in building installations > 230 V DC
• Applications in the field of photovoltaic and solar technology > previously 1000 V DC, in future up to 1500 V DC
• Applications in the field of eMobility > up to 1500 V DC

A measuring range between 12 and 1000 V AC and up to 1500 V DC is therefore ideal for all professionals, as the voltage tester can be used in as many different ways as possible. At the same time, it already covers voltage levels that will be standard in the future, especially in the field of renewable energies.

Measurement category
Measuring and testing devices must correspond to one of four measurement categories. These categories provide information on the area in which the device may be used. You can find more detailed information under this link:

You can find more information about the measurement categories in our multimeter category:

To the multimeter category

In Germany, two-pole voltage testers must comply with measurement category CAT 4. This means that all two-pole voltage testers that fulfil the requirements are approved for building installations. In addition to the measurement category, the maximum permissible voltage level is also decisive. There are three levels that should be taken seriously for your safety: 

• Up to 300V AC
  
• Up to 600V AC 
  
• Up to 1000V AC

Display of the voltage level

All two-pole voltage testers show the user the voltage level in stages. LED lamps light up to indicate the corresponding level. The measuring range can be categorised differently. The usual levels are 12 to 690 V AC / DC.

In addition, higher-quality devices have a digital LCD display. Here, the device indicates the exact voltage level in digits on an illuminated or non-illuminated display.

What other functions do two-pole voltage testers offer?

Professional devices in particular offer other functions in addition to simply checking for the absence of voltage. These include

• Continuity test:
  One of the most important measurements in electrical circuits is the continuity test. With many two-pole voltage testers, you can easily check whether a line is continuous. Most devices indicate continuity by illuminating an LED light. It makes sense if the visual display is combined with an audible, loud signal. This allows you to concentrate fully on the measurement. The continuity test is indispensable in the professional sector.
• Rotary field display:
  Another useful feature is an optical display that visualises whether the circuit is clockwise or anti-clockwise.
• Non-contact voltage test:
  Conventional two-pole voltage testers must be integrated into the circuit with the test probes for the measurement. Devices that also offer an initial non-contact test for the absence of voltage offer greater convenience. This is useful, for example, if you are looking for cable breaks. However, the all-pole test for absence of voltage prescribed by the standard via integration into the circuit does not replace non-contact testing. It only serves as an initial indication!
• Inspection of FI / RCD circuit breakers:
  Many two-pole voltage testers are suitable for testing RCDs and RCD circuit breakers.
• Single-pole phase test
  You can use this function to quickly and conveniently carry out an initial indication of the absence of voltage. If you have a voltage tester with this function, you do not need another single-pole test device.
• Torch function
  This is particularly recommended if you frequently measure in poorly lit locations.

What should you consider when buying?

As mentioned above, pay particular attention to the measuring range. What voltage levels do you want to measure? This is the most important point for your individual requirements. The following criteria are also important:

Basic criteria:

• Complies with DIN EN 61243-3 VDE 0682-401 and / or GS VDE test seal.
  These devices are approved to the highest standards to ensure that they are voltage-free.

• Measurement category CAT 4
  The device must also comply with measurement category 4. This must be indicated on the device or in the operating instructions.

• Protection class
  Two-pole voltage testers are electrical equipment. There are types of protection for these. The degree of protection provides information on the safety of the equipment with regard to protection against contact, foreign bodies and water. To ensure that your device can be used safely even under adverse conditions, it should have a protection rating of at least IP 64. It is then dust-tight, fully protected against contact and dirt and protected against splash water on all sides.

Special criteria, especially for electricians:

• Test function for RCD / RCD circuit breaker
  In order to reliably check the correct tripping of residual current circuit breakers, it must be possible to switch on the load at the correct level using the two-pole voltage tester. According to legal requirements, residual current circuit breakers must not trip between 15 and 30mA. The switchable load should therefore be at least 30mA.

• Locking the handles
  On the one hand, a locking option for the handles is useful for proper transport. More important, however, is the ability to check conventional earthed sockets for the absence of voltage with one hand. The locking mechanism fixes the test probes at a distance of 14 mm. This ensures that you can easily test the socket outlet phases with one hand.

• Interchangeable test probes
  The test probes of the device should be interchangeable because you need test probes with different diameters at different measuring points. In most cases, you can screw larger test probes onto the tips that are firmly attached to the handles as required. Pay attention to the size specification: For testing procedures on terminals, for example, you need thin tips between 2-3 mm. Testing sockets is easier with 4 mm tips.

• Continuity test, rotary field direction display, resistance measurement
  Additional functions apart from checking for the absence of voltage are mandatory in the commercial sector. This allows your device to support you in many different testing and measuring processes, enabling you to work more efficiently.

Comparison of the two-pole voltage testers from Wiha

Wiha offers three two-pole voltage testers. The following table clearly summarises how they differ from each other: