EXTICOV-CCF Cover with special single-slope fire suffocating slats


Fire suffocating cover for oil-filled electrical transformer pit

The EXTICOV-CCF™ fire suffocating cover with slats for retention pits in electrical substations responds to the risks of hydrocarbon pool fires in transformers. This fireproof system, tested several times at the CNPP in accordance with ERDF (ENEDIS) specifications, complies with current international standards and laws and allows pits to be rehabilitated by replacing the bed of pebbles on gratings.




The EXTICOV-CCF™ system is recommended for all types of retention pits preferably indoors :

  • For recovery pits, fitted with fire-stop flaps, which communicate with either a fire-stop siphon or a remote pit directly.
  • For so-called full retention pits, where at least 100% of the volume of oil potentially on fire will be in the retention pit

The EXTICOV-CCF™ cover consists of reinforced single-slope fire shutters made of SONEC® technology 20/10 galvanised steel, placed in metal frames. These are then installed at the top of the pit on angles provided for this purpose.

Single-slope shutters are an old patented technology, specially designed to accelerate the passage of burning hydrocarbons into the pit, under the shutters, much more quickly and efficiently than current models of double-slope or multi-slope shutters.

Once the hot oils are “trapped” in the pit, the fire self-extinguishes almost instantly because the oxygen oxidant is not replenished. As the smothering process is very rapid, the temperature rise inside the pit is low and the thermal runaway that could accelerate the spread of the fire is rendered almost impossible. The device therefore acts passively and simultaneously on 2 of the 3 components of the fire triangle in a simple and effective way: temperature and the oxygen oxidant.


Description of the EXTICOV-CCF™ standard range:

  • Special fire-stop shutters made from 20/10 Z275 continuous galvanised steel. Their robustness ensures that if the grating is forgotten, an operator will not be able to walk through the shutters, unlike existing systems.
  • Shutters slid into a special frame made to measure in hot-dip galvanised steel to ISO EN1461-2022 standard
  • Non-slip gratings in hot-dip galvanised steel that allow you to walk around the pit without the risk of deforming or moving the dampers, thus maintaining the compliance of the firewall system during operations on the pit.
  • System load-bearing capacity of 250 daN/m² to 500 daN/m² (distributed load) as standard, depending on customer requirements
  • Unique last-flap lockout system with CCF-STOP™, maintenance flap lockout screw

Accessories and options

The complete EXTICOV-CCF™ system is custom-made for easy installation. On request, our SANERGRID or SONEC teams can visit your site to take measurements. Our engineering department, based on your plans or a manual measurement, designs and draws the system as well as the supporting structures. This enables us to offer some of the highest resistance per m² on the market. Please contact us for further information.

This range also includes a number of accessories to suit your needs:

  • SPI filtration system, when the tank is used outdoors to allow continuous drainage of rainwater; installation under the fire blanket using a concrete manhole attached to the tank.
  • Non-slip access hatch for filters, SPI pre-filtration cages or simply access to the bottom of the pit.
  • On request, we also work with stainless steel or GALVAGRID® for salt spray resistance equivalent to or better than C5H or CXS.
  • MALT modules, for earthing using braids and lugs; specify the section to be quoted.
  • Self-perforated, seamless grating 30 x 30 CUBE, non-slip, seamless and with no risk of weld breaks between two pieces of electro-forgewelded grating.

Depending on the configuration of your project, we can offer you other references of EXTICOV-LHD fire-resistant grating covers  recommended for outdoor use or use with high organic contamination in order to reduce the preventive maintenance required for fire-resistant shutter covers (see Use and maintenance tab).

Technical data

Additional information

Conditions of use

indoor, outside



Fire resistance


Use and maintenance

The advantages of being supplied in made-to-measure frames mean that installation on retention pits is quick and easy.


Before installing the cover:

Retention pits must be clean, smooth, free of pebbles or fire-retardant stones, free of hydrocarbons, re-cleaned or re-sealed. The walls of the pits and concrete blocks must be as flat and straight as possible, or be rendered, and capable of supporting the SPITFIX (not supplied, additional estimate required), the support angles and the weight of the frames and gratings.


Installation of the cover:

  • Position the angles at the correct height.
  • Drill holes in the concrete where the pre-drilled angle holes will be, then fit the SPITFIX
  • The frames are delivered assembled with the shutters and identified using numbers that follow the numbering on the BPE drawing approved at the time of going into production. Position the frames as shown on the drawing.
  • Earth the frames together if earth continuity is required (MALT KIT not included, request a quotation).
  • Place the gratings on top of the frames.


Maintenance of EXTICOV CCF extinguishing cover:

Unlike EXTICOV LHD fire-retardant grating roofs, EXTICOV-CCF flap-type fire-retardant roofs, because of the semi-mobile design of the flaps and the grating covering them, require more extensive maintenance.

Regular visual inspection of the equipment should cover the following points:

  • Cleaning of organic materials (leaves, branches, moss, etc.) which may be positioned between the gratings and the shutters, and which could either leave the shutters permanently open, or block the passage of oil between the shutters. Depending on how dirty the site is, we recommend using compressed air or a high-pressure Kärcher.
  • Non-overlapping fire dampers.
  • No missing flaps.
  • Presence of CCF-STOP™, maintenance flap lockout screw.
  • Integrity of the fire shutters, no deformation or damage (knocks, impacts, rust, etc.).
  • State of ageing of the hot-dip galvanising protective layer and potential touch-ups.
  • The frequency of these checks depends on the constraints of each site, depending on its degree of corrosion, dirtiness, presence of organic matter, etc.

Refer to the user manual for further details.

The owner of the equipment is responsible for and liable for any failure to comply with good operating practice and for any failure to deal with anomalies and defects in the field.

Additional information

Storage facilities for high-voltage substations in contact with polluting products must comply with the standards and laws in force.

Our natural and rapid dielectric extinguishing device EXTICOV® -CCF™ is a SONEC model created in 2007, a single slope model proven in the electrical industry for 30 years, trademark registered with the INPI.

EXTICOV-CCF™ roofing complies with the following legislation:

  • NF C13-100 and NF C13-200, which prevent the risk of overcurrents and earthing problems. They protect people from direct or indirect contact with conductors, and electrical installations from the risks of fire, short circuits and lightning.
  • NF EN 61936-1, relating to the design and installation of electrical installations, which requires a watertight retention tank representing 100% of the volume of oil used.
  • NF C17-300, which deals with fire protection for electrical equipment containing dielectric liquids.

SONEC flap cover tests carried out at the CNPP, national fire laboratory, in 2009 and 2011.

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