Safety is always the uppermost priority. This principle applies particularly whenever energy cables have to be cut. And not only because § 6  of the accident prevention regulations pertaining to “Electrical systems and equipment” specify that activation has to be determined before any cutting work may begin and that any endangering of persons has to be avoided at all costs.
In the everyday working situation it is sometimes difficult to determine whether an underground cable really is activated or not. Safety cutting units are used in such cases to avoid any risk of hazards arising.
In principle, these compact units consist of four component parts: a cutting head, an insulating hose, an earthing system for potential equalisation and a hydraulic pump.
The pump is available either as a foot-operated or battery-powered hydraulic version. The only difference here is the convenience factor – both models ensure safe working.
Safety cutting units are practical and operator-friendly when being used.
Firstly, the cutting head has to be attached to the energy cable. There are two types of cutting head: the open cutting head is particularly suitable when work has to be carried out in confined spaces whereas the guillotine cutting head, which can be placed completely around the cable, is used when sufficient working space is available.
Irrespective of which cutting head is used to carry out the work, it is important that there are no other cables besides the energy cable in the vicinity of the cut.
The guillotine cutting head can prevent the unintentional severing of other cables thanks to its “closed” cutting system.
After the cutting head has been attached to the cable, the hydraulic hose then has to be rolled out in a subsequent step. This hose is a good 10 metres long and filled with non-conductive hydraulic oil.
The hose ensures an even level of power transfer between the drive unit and the cutting head. The hydraulic hose is attached at one end to the pump with a quick coupling while the other end is firmly connected to the cutting head.
Before the actual cutting process can begin, the drive unit has to be earthed using the earthing kit.
Some models, such as e.g. the Klauke ASSG safety cutting unit, are equipped with a remote control, enabling the cutting process to be conveniently steered and implemented from a safe distance.
In the case of the battery-powered safety cutting units, the integrated software checks whether the battery capacity is adequate to manage the cut. If the capacity is insufficient, the cutting process will not start, thus ensuring a maximum in terms of safety.
Safety cutting units by Klauke are subjected to the DGUV Test (BG [professional association]) – a testing and certification system offered by the German Social Accident Insurance. The DGUV symbol is a voluntary distinction and stands for a high degree of quality and safety.
Safety cutting units are tested on the basis of “GS-ET 23: Principles for the Testing and Certification of Motor-Driven Cable Cutting Equipment”. Subsequent modifications are impermissible since the units are certified as an overall system. The DGUV symbol would otherwise become invalid. Even the transportation housing is included as a part of the test and is the reason why the units may only be transported in this approved enclosure.
There are also safety cutting units on the market that carry a declaration of conformity. The manufacturer gives an assurance with this declaration that its products are in line with the principles applied in the DGUV test although they have not been specifically tested as safety cutting units by the testing and certification institute.
Klauke advises against the use of such generally-tested equipment. Only a certified test pursuant to GS-ET 23 will ensure a safe cutting unit.
A safety cutting unit needs to be serviced every two years. This work covers e.g. an exchange of the hydraulic oil and may only be carried out by the producer of the equipment.
To ensure the perfect condition of the unit in between the general services, Klauke recommends a visual inspection before and after every cutting operation. Moreover, the safety cutting unit should be thoroughly cleaned after use on each occasion.
No risks should be taken when selecting a safety cutting unit. Irrespective of whether the unit has a foot-operated or battery-powered hydraulic drive, approval and certification of the unit by the DGUV is a dependable testing symbol. Regular maintenance and careful treatment of the unit prolong the service life of the appliance and also enhance safety during the cutting operation.
The Klauke team of experts is available for advice on any queries surrounding the theme of safety cutting units and can be reached under: Klauke-Utility@Emerson.com.
A detailed video depicting the precise application of the Klauke ASSG can be viewed on the Klauke Youtube channel: Link to Klauke Youtube channel