Cable supporting systems with maintained functionality in fire

The risk of fire can never be eliminated, even with the use of various regulations and measures. During a fire the electrical distribution is exposed to high load. Especially in gathering areas the delivery of electricity must be maintained as long as possible for selected electrical equipment in protected escape and intervention routes. Maintaining the delivery of electricity for a stipulated time is achieved using the cable support systems, which function during a fire. The fire resistant cable supporting system, manufactured in KOPOS KOLÍN, fulfills the requirements given by the relevant standard and regulation.

During the designing of the fire resistant cable support systems (up to 1 kV), it is necessary to:

  • on the basis of the fire report:
  • know the level of the fire safety of the fire zone, which is determined on the basis of the calculation of the fire risk, the construction system of the building and the height of the building or the floor
  • characterize the fire resistance of the load bearing constructions inside the fire zone, which do not secure the stability of the building and which do not carry the fire separating structures nor do they form them
  • know the type of the protected escape line
  • design and secure the methods of the delivery of electricity from two sources that are independent of each other, serving for securing of fire prevention of the buildings (for example fire elevator, evacuation elevator, firewater boost pump, emergency lighting) so that during the outage of the delivery from one source the deliveries are fully secured from the second source for a period of the assumed function of the equipment
  • eliminate the effect of the surrounding installations on the cable supporting system
  • support the suitable construction of the support system according to the level of the necessary fire resistance
  • select the wires and cables securing the function and the control of the equipment used for the securing of fire prevention for the buildings and stipulate their placement; electrical equipment which does not serve for securing fire prevention of a building are evaluated with regards to fire prevention when a) the wires and cables are placed loose without further protection, b) the weight of the insulation of the wires and cables, eventually the flammable parts of the electrical distributions, exceeds 0.2 kg per m3
  • elaborate a “Report about determining external effects” according to the ČSN 33 2000-3 commission wise. The members of the commission are the electrical engineer, the fire technician, the safety technician and the investor. Furthermore, according to the focus of the building there is also present the technology expert and specialists with electrical requirements, as for example air technician, heating technician etc. The members of the commission must also be specialists in the field for which the building is being built.

Testing the fire resistance of the cable supporting systems for integrated maintaining of functionality

The fire resistance test is to verify the activity of the cable supporting system of the cable supporting system during a fire and to prove that essential life functions in thebuilding (fire elevators, evacuation elevator, firewater boost pump, emergency lighting, fire alarm, emergency exits..) remain maintained for the stipulated time. A uniform European standard for safety resistance and its testing does not yet exist.

The German standard DIN 4102 section 12 is considered as a reference standard: Maintaining the functionality of the cable supporting systems.

In the Czech Republic the testing of the fire resistance of the construction of the cable supporting systems is specified by the harmonized standard ČSN EN 1363.

The new standard ČSN 73 0895 specifies the methods and conditions for resistance testingcable routes under fire conditions.

 

Identical elements of the standard ČSN 73 0895, German standard DIN 4102 No. 12 a STN 920205:

  • composition of test samples and norm constructions
  • connection of electrical circuits
  • possibility of partial compensation of placed cables by a steel weight
  • dimensions of cable trays, cable ladders and clamps:

cable trays:

  • maximum allowable width 300 mm (perforation percentage 15 ± 5 %)
  • sidewall height 60 mm
  • thickness of metal sheet 1,5 mm
  • weight of cables max. 10 kg/m
  • distance of supports 1 200 mm

cable ladders:

  • maximum width 400 mm
  • sidewall height 60 mm
  • thickness of metal sheet 1,5 mm
  • weight of cables max. 20 kg/m
  • ladder cross-pieces at a distance of 150 mm
  • distance of supports max. 1 200 mm

independent cable clamps:

  • distance 300 mm
  • width clamps ± 15 mm

supporting profiles with clamps

The certified constructions the design of which is consistent with the parameters of the standard are called standardized (standard).

KOPOS KOLÍN a.s. produces fire resistant systems conforming to the above stated standards and the regulation. They include cable trays JUPITER KZ with metal sheets thick 1.5 mm and a cable tray with cross-pieces distant 150 mm.

The certified constructions the design or dimensions of which are different from the above stated standard and regulation are called non-standardized (non-standard).

KOPOS tries to accommodate the demands of its customers as for price and offers them fire-resistant systems for more favourable prices. It is possible to reduce the price of fire resistant routes using a metal sheet of a thickness smaller than the one determined by the standard, fewer supports etc. The standard allows testing of the routes which are then marked as not standardized (non-standard).

The non standard routes include the routes created by MARS and JUPITER cable trays with integrated couplings with the metal sheet thickness of 0.7; 1,0; 1.25 mm, routes of cable ladders with the distance of cross-pieces 300 mm; further there are supporting metal trunkings, systems with cable catches, routes created by steel pipes, and fire resistant boxes.

 

Cables for systems while maintaining the functionality during a fire:

Safety power and data cables with the functionality of resistance against fire must likewise pass fire resistance tests according to the valid regulations.

 

Classification class of individual standards

 ČSN 73 0895DIN 4102 č. 12STN 920205
Temperature course of the testThe standard temperature
time curve (°C)
Constant
temperature (°C)
Other fire
scenario
The standard temperature
time curve (°C)
Identifying the classes of fire functionalityP 15-RPH 15-Re.g. P750 90M-PS 15
P 30-RPH 30-RE 30PS 30
P 45-RPH 45-R-PS 45
P 60-RPH 60-RE 60PS 60
P 90-RPH 90-RE 90PS 90
P 120-RPH 120-RE 90PS 120