GENERAL ABOUT ROOF APPLICATIONS
In most cases, a new feeding cable must be installed from the buildings distribution box (usually in the ground floor or basement) to provide the roof application with power.
For larger applications a distribution board is installed on the attic to distribute power to the plants control cabinet. The distribution board can be equipped with an energy meter to measure the power consumption of the roof construction. All the distribution boards should be equipped with lockable main switch to prevent electric shock during servicing.
The number and size of the control cabinet depends on the size and design of the roof.
Rules of thumb for power feeding:
Calculate the total amount of heating cable by summing the number of meters roof / gutter which re to be frost protected.
Add the number of drainpipes x length plus 1m per drainpipes if they connect to the surface water.
Total amount of heat cable calculated to be consumed for your roof application x 50 W / m gives you the total required power on the roof, add on 20-30% margin: 300m, gives > 300 x 50 x 1.3 = 19.5 KW
At roofs facing different directions or roofs with long routes should be divided into sections to improve the selectivity of regulation and to limit wiring with connection cables on the roof. This provides advantages in that only those parts of the plant there.
Consideration must be given to the suns heat in summer combined with UV-radiation which generates high temperatures and ice and cold in winter means a tough environment, which puts high demands on materials used on roofs. These materials should be able to withstand temperatures down to minus 25-30 degrees and up to plus 50-60 degrees without damage.
These requirements exclude virtually all installation- and heating cables made with PVC-jackets. Suitable materials are thermoplastic / rubber / fluorine polymers.
Consideration of galvanic currents must be taken when selecting materials for fasteners, on the grounds that a wrong choice can lead to roof cover panel being corroded in a short time.
We believe that there is reason to change the installation methods for roof installations due to the serious deficiencies that present a risk of injury to persons and property.
A close cooperation with Elsäkerhetsverket (Swedish National Electrical Safety Board) and Plåtslagarnas Riksförbund (The national association of the sheet-metal workers) has done that we recommend that in future only use material that is capable of the demands in this environment.
|Easy installation and service.
Velox Frost Protection of Roof – The only system with plug connection. This reduces the electrician work on the roof where roof experienced sheet-metal workers easily installs and connect standard heating lengths.
Electrician is though needed for the drawing of the feeding cable and the installation of distribution boards, control cabinets and connection boxes on roofs.