Why power utilities use FRP grating

In outdoor areas of substations, switching stations and power plants, grating faces rain, condensation, ultraviolet light and industrial contamination. Galvanized steel grating rusts in heavily polluted areas, and the rust can later contaminate insulator surfaces.

FRP grating does not conduct electricity, is non-magnetic and does not spark, and its low weight suits manual handling and maintenance near live equipment. These properties are a reason to choose the material, but they do not replace electrical safety rules.

Power projects usually define grating in the technical specification: load class, fire class, slip surface, colour and earthing method. Selection should start from the specification, not from a product brochure.FRP grating solutions for the power industry

Substation walkways and equipment areas

Walkways in a substation link bays, the control building and maintenance routes, and their width must allow two people to pass and tools to be carried. Cable trenches, drains and foundations below the walkway affect how the grating is supported.

Platforms around equipment areas are usually set out with guardrails and warning signs. Grating colour can help distinguish zones, but it cannot replace warning boards or electrical clearance marking.

Outdoor walkways need falls or gaps for rainwater so water does not stand. Where cables or equipment sit below, the cover type must keep out small animals and debris.

Walkways in equipment areas also need to allow for temporary power and test equipment during maintenance. Where cable trays run below, walkway beams must not bear directly on the tray or its cover; load should reach the foundation through independent supports, so that stepping on the walkway cannot damage cables.

Cable trench covers

Cable trench covers must carry load, keep water out, resist removal and still open easily. Trenches in substations often carry people or vehicles, so the cover class follows the actual traffic load and a light cover is not a substitute.

• Load class set by the people and vehicles that actually cross.
• Panel weight and opening method matched to maintenance frequency.
• Overlap long enough that the cover does not tip when stepped on.
• Locks or hold-down strips where removal or unauthorised opening is a risk.

FRP covers are light enough for one person to lift, which suits trenches opened often; the same lightness means they can be moved aside, so important locations need locks or hold-down strips to prevent unauthorised opening.

Sealing and drainage must be considered together. A fully sealed cover traps moisture and encourages condensation inside the trench, while a drain hole lets water and silt in. A common approach is a gap between covers with a fall in the trench, following the project electrical design.Cable trench and walkway cover products

Dielectric properties and live-area safety

FRP is an insulating material with high surface resistance when dry, so it can serve as a working surface near live areas. That insulation is degraded by contamination, moisture and surface tracking, and dust or salt spray can turn the surface into a conductor.

FRP grating is therefore not a permit for live work. Clearance, proving dead, earthing and protective measures still follow the electrical safety rules; the grating only reduces part of the risk of accidental contact and step voltage.

Step and touch voltage depend on soil resistivity and the fault current path. An insulating grating changes the surface potential distribution, so the electrical discipline should assess the design rather than assume that an insulating panel is automatically safer.

Where static or equipotential bonding is required, fit earthing terminals to the specification. Ordinary FRP grating does not conduct and cannot earth itself, which matters especially near cable basements and relay rooms.

Fire, arc and contamination

Fire requirements in power facilities concentrate on cable-dense areas and control rooms. The resin system of the grating should state a flame retardant class and be supported by flame spread and smoke density test reports.

Arc fault temperatures are far above those of an ordinary fire, and FRP decomposes and carbonises under an arc. Grating can be used where arc risk is low, but it is not an arc barrier, and those areas need protection to the electrical code.

Contamination is the enemy of outdoor insulation, and dust on grating is hard to clean. A smoother surface with a larger mesh reduces dirt build-up, and washing should be part of the maintenance plan.

The fire load inside a cable trench comes from the cables themselves, and the fire class of a cover can only slow flame spread, not replace sealing and fire compartmentation. Cable penetrations through walls or floors need fire stopping to the electrical design, and covers and seals should be accepted together.

Supports, fixing and earthing

Support spacing for FRP grating comes from the load table. Substation walkways may carry maintenance vehicles, tool boxes and several people at once, so the design load cannot assume a single person.

Fasteners are usually stainless, with attention to galvanic corrosion where they meet steel supports. Where equipotential bonding is required, fit dedicated earthing tags to the electrical design rather than relying on the grating to conduct.

Long walkways need expansion gaps to prevent buckling as temperature changes. Cover overlap on the trench edge must be long enough to stop the panel tipping or sliding when stepped on.

Where covers and walkway panels are mixed, number them on the drawing and mark the opening direction. A cover has the slip surface on top and the closed layer below; fitted upside down it loses slip resistance and traps water in the trench.

Slip resistance and outdoor durability

Outdoor substation walkways are slippery in rain, snow and ice, so an anti-slip surface is necessary. A gritted surface performs better when wet, though ice still needs removal and warning.

Ultraviolet light chalks and fades the FRP surface, which is normal ageing. Confirm that the resin contains UV stabilisers and choose light to mid colours to limit surface temperature rise.

Spare parts management affects long-term appearance too. Pattern and colour can vary between batches, and one new panel in an old walkway stands out; it is worth ordering a few spare panels from the same batch with the first delivery so replacements match.

Routine inspection focuses on cut edges, fasteners and cover overlaps. These are where edge sealing fails first, rust stains appear and fixings loosen, and prompt repair avoids replacing a whole panel.Insulation and weight benefits of FRP grating

One-line rule

For power utilities, confirm load, fire and earthing requirements from the specification first, then choose cover or walkway panels by area, and finish with slip surface and edge sealing. Insulation is a material property; safety comes from design and rules.

On site, accept walkways, covers and earthing as three separate items, then review the junctions between them. Junctions are where edge sealing, overlap and equipotential bonding are most often missed, and where problems show up years later.