Earthing and short-circuiting devices
Labour protection laws obligate!
Employers are responsible for the health and safety of their employees. According to labour protection laws, employers must ensure that all necessary protection measures are taken and observed when working on electrical installations.
Therefore the relevant parts of an installation are isolated from supply voltage when working on electrical installations and equipment. However, simply hitting a switch for isolation from supply voltage is by far not enough. From isolating the installation from supply voltage to releasing the work location, further reliable information on the state of the installation, measures to prevent maloperations and malfunctions, protection against maloperations and malfunctions as well as protection against risk potentials of adjacent parts of the installation is required. For this purpose the following five safety rules in accordance with EN 50 110-1 have to be observed:
- Disconnect completely
- Secure against re-connection
- Verify that the installation is dead
- Provide protection against adjacent live parts.
Every certified electrician knows that these rules can save his life. But what about the safety and reliability of devices and tools used to gain vital information or secure sequences of operation? Every measure is only as safe as the safety devices used.
The most important rule of the five safety rules is earthing and short-circuiting. This ensures that the installation is isolated from supply voltage while work is carried out even in the case of interference voltages, atmospheric surges or accidential re-connection. However, this safety measure is also as safe as the device used.
Time also leaves its mark on these devices. Corrosion may reduce cross-sections of earthing and short-circuiting cables thus challenging safety. Only suitable safety devices can prevent dangerous voltages or electric arcs at the work location. This means that devices have to meet the purpose of application, have to be dimensioned correctly, attached according to the installation instructions and be in proper condition.
Any damage of the cable sheath or protrusion of bare conductors presents severe damage which means that the device cannot be used anymore.
Before further use, devices the cable entries and cable structure of which cannot be examined visually (green-black colouration, break of conductor strands at the break point) have tested for the reduction of area of the cable. The safety devices also have to be marked accordingly. Devices without manufacturer name, date of production, cross-section, material and double triangle marking on the cable do not correspond to the latest standards. Before use, a safety test has to be performed for such devices according to the latest standard. This does not apply to earthing and short-circuiting devices which are manufactured and tested according to the current version of IEC/EN 61230. DEHN + SÖHNE is your reliable partner.
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