Frequently asked questions about cables
Why are there differences between the metre marking and the length indication LS/RE?
The metre marking on the sheath is only an aid for handling the cables. For technical-physical reasons, the metre marking on the sheath has a tolerance range of ±0.4% (i.e. max. 4mm per 1m cable), which is why embossing wheels are also not calibratable. For billing purposes, the length specifications on LS/RE are used, for which we only use calibrated measuring equipment.
Where can I find the current carrying capacities of the cables?
The information on the current carrying capacity for the respective product can be found in the “technical data” tab. The tables can be found in the service section.
What does "Procedure B" mean for the isolated overhead lines NFA2X / (N)FA2X?
In procedure B, the insulation of the neutral conductor is corrugated (i.e. has many knobs), whereas according to VDE 0276-626, the neutral conductor is smooth.
What is the Euro class of a NYM (-O /-J) cable?
Practically all cables with PVC sheathing can comply with Euroclass Eca.
However, the manufacturers must carry out the corresponding tests at a notified body. You can recognise tested goods (from 1.7 at the latest) by the CE mark and the corresponding declaration of performance.
In any case, NYM must be marked, as these cables are intended for permanent use in buildings.
Why is UV resistance so important for cables?
→ Protection against UV rays outdoors
UV rays destroy the polymer chains of the plastic and make it brittle, cracked and thus reduce the mechanical properties. Microbes and moisture can now penetrate through microcracks and damage the material even further. If the sheath is broken, the core is exposed to environmental influences and safety is no longer guaranteed. This means that the cable must be replaced. If cables are not UV-resistant, replacement is necessary after only a few years in extreme cases. Our best materials are tested at a radiation dose equivalent to 20 years of UV exposure in Central Europe.
→ Protection against UV rays indoors
UV rays are not only to be considered outdoors. Even behind window glass, not everything harmful is filtered out. In addition, there are the increasingly popular daylight lamps, which, depending on the model, contain a certain amount of UV so that vitamin D can be formed.
If, in extreme cases, 2 and 20 years are compared, this means a service life of up to
10 times the service life, which saves up to 90% plastic and a lot of installation work.
You will find this pictogram in the product description for our UV-resistant cable types.
CPR: Are cables with functional integrity (E30, E90) subject to the Construction Products Regulation?
No, they are not subject to the CPR:
Cables according to CPR fulfil high requirements regarding their behaviour in case of fire (reaction to fire).
The aim is to limit the spread of fire and smoke.
In addition to fire propagation, heat and smoke development, acidity (freedom from halogens) and dripping of burning particles (and some more) are defined.
Cables with functional integrity describe the resistance of the complete cable system in case of fire (resistance to fire).
The aim is to guarantee the function of safety devices such as alarms, signposts and extinguishing systems even in the event of fire.
These cables are tested in the system – i.e. including the fastening – to see whether there is a short circuit within the required time.
Cables with functional integrity therefore have a completely different objective and are therefore explicitly excluded from the CPR (see DIN EN 50575 section 1).
CPR : What if cables are permanently installed only a few metres inside (a few) buildings? Do these also fall under the CPR?
In principle, the CPR also applies when laying a few metres inside buildings. It remains to be seen how this regulation will be implemented in the corresponding state building codes. We are also waiting for the specifications from the authorities.
CPR: Stocks - What happens to the goods that are currently in stock? Are they excluded from the new regulation?
A declaration of performance in accordance with article 4 of the EU Construction Products Regulation has to be issued for products placed on the market as of 01.07.2017, regardless of whether they are in stock or not.
Many of our products have already been tested. If you have any further questions, please do not hesitate to contact our sales team!
What does « standard length » mean?
The standard length is the most frequently requested length of a cable type because it combines moderate handling effort (common drum size) with favourable production conditions, and thus offers advantages for both sides.
Of course, you can also order any other length from us.
What does « maximum production length » mean?
The maximum production length is the largest length that can be produced in one piece – i.e. on one drum. Order quantities that exceed the maximum production length are therefore always divided among several drums.
As standard, order quantities are divided into standard lengths.
Please inform our sales team of your requirements when making your enquiry.
In which unit are the dimensions of the cores specified?
Power cables are specified in mm²
4×50/16 – 4 cores with a cross-section of 50 mm² each and a screen cross-section of 16 mm²
3×150 + 3×25 – 3 cores, each with 150 mm² and 3 cores, each with 25 mm² cross-section
Solid telecommunications and signalling cables (copper conductors) are specified in mm
40x2x0.8 – 40 pairs (=80 cores) with 0.8 mm conductor diameter per core
80x4x0.9 – 80 quads (=320 cores) with 0.9 mm conductor diameter per core
Finely stranded telecommunications and signalling cables (copper conductors), on the other hand, are specified in mm² (cf. power cables)
1x4x0.7 mm² – 1 quad (=4 cores) with a cross-section of 0.7 mm² per core
Why isn’t it specified in a single consistently unit?
In the case of a single-wire conductor, the conductor diameter and cross-section can be mathematically easily converted into one another, but the conductor diameter is easier to measure. With stranded or finely-stranded conductors, there are gaps between the individual wires, which vary depending on the manufacturer/process – the entire cross-section of the conductive material is important for the respective transmission properties.
Frequently asked questions about laying
Can I also lay cables directly in water?
We also stock cables that are approved for laying directly in water.
Ask us! Our sales team will be happy to help you!
What is meant by the bending radii of the cable?
The multiple bending radius indicates the minimum permissible radius by which the cable may be bent repeatedly and also under tensile stress – e.g. when rewinding.
The single bending radius indicates the minimum permissible radius by which the cable may be bent when laid in the end position. Here, the additional conditions “shaping using a template”, “cable temperature >30°C” and “without tensile stress” apply. Why is this necessary? When a cable is bent, the inner side is compressed and the outer side is stretched. This means stress for the material. These values must be adhered to in order to avoid damage and thus ensure the service life.
Are underground cables UV-resistant?
Unfortunately, there is no generally valid answer to this question, but we do stock cables that are both buriable and UV-resistant – just ask us! Our sales team will be happy to help you!
Can I also lay cables when the outside temperature is below the minimum installation temperature?
The installation temperature refers to the temperature of the cable. If you can ensure that the cable temperature does not leave the permissible range, you can also lay the cable at lower outdoor temperatures.
What is meant by the installation temperature of the cable?
Not only people, but also materials have a “comfortable temperature”. If a plastic material gets too cold, it becomes hard and can crack when moved, as is the case when laying cables. The installation temperature indicates the temperature at which the cable can be safely installed.
How are the cores of petrolate-filled cables cleaned?
All you need is commercially available rapeseed oil and cloth cleaning rags.
1. rough cleaning:
Wipe the petroleum jelly from the strands/fours with a clean and dry cloth – paper towels can also be used here.
2. final cleaning:
Using a cloth rag soaked in rapeseed oil, wipe the remaining petrolate from the strands – the stranding of the quads must be dissolved here.
3. dry wipe:
Wipe the residue of the rapeseed oil from the strands with a clean and dry cloth – paper towels can also be used here.
Frequently asked questions about logistics and cable drums
How can I register KTG loan drums?
You can register your drums with our handy app for iOS and Android.
You can find the app on our website in the Company section.
What is the net weight of the different cable drums?
Weights, dimensions and many other properties of our cable drums used can be found → here
How long is the rent-free period of the KTG cable drums?
The rent-free period is defined by the conditions of the KTG. Normally, this is 6 months from the date of the delivery note.
What is the procedure for collecting empty drums?
The drum collection can be initiated by email or via the KTG homepage.
They will then contact you directly to arrange an appointment. Alternatively, you can also use our special app.
You can find it → here
What are the conditions for delivery on KTG loan drums?
If deliveries are made on loan drums, they shall be made in accordance with the → conditions of the cable drum company (“Kabeltrommelgesellschaft” KTG).
Frequently asked questions about documents
Where can I find the current carrying capacities of the cables?
The information on the current carrying capacity can be found for the respective product in the “technical data” tab.
The tables for the technical data can be found in the → Service section.
Frequently asked questions about pricing
What does the copper base that is included in the offering price mean?
The copper basis is a fixed but fictitious copper price in €/100kg. Since the metal price usually makes up a large part of the cable price, it is common practice in some areas to include the metal costs (which are subject to the fluctuations of stock exchange trading), at least at a fixed metal price, which is intended to facilitate the comparability of offers.
What is the net basic price (NG)?
The net basic price is the net hollow price plus a metal value share – depending on the metal base.
This share is in turn subtracted in the metal value settlement.
What is a metal number?
The metal count is the calculatory metal content of copper, aluminium or lead in the cable, stated in kg per km.
How do you determine the value of a copper base 100?
In the following calculation example, the copper base 100 is calculated:
Copper number 312 (kg/km) copper base 100 (€/100 kg) -> 312 x 1,00 € = 312,00 €/km
or copper number 312 (kg/km) copper base 100 (€/100 kg) -> 3,12 x 100,00 € = 312,00 €/km