Campervan Cable Routing, Trunking and Loom Guide

Poor cable routing causes more campervan electrical faults than any component failure. Cables that chafe on metal edges develop shorts. Cables run through wet areas corrode and fail. Cables not properly supported sag, pull on terminals, and work loose over thousands of miles of vibration.

Good cable management is not just about looks — though a tidy installation is genuinely easier to fault-find and modify. It is about building a system that survives years of road use. This guide covers every technique you need for a professional, durable installation.

For cable sizing guidance, see our wire gauge calculator. For routing rules specific to solar panel cables, see our solar cable gland guide.

Plan Your Routes Before You Start

The most important step in cable management happens before you pick up a drill. Sketch out where every major cable will run:

• Battery location → fuse/bus bar → fuse box
• Fuse box → each 12V appliance
• Solar panels (roof) → charge controller (usually near battery)
• DC-DC charger → battery
• Inverter → battery (short, heavy run)
• Shore power inlet → consumer unit

Identify where cables need to pass through the van's structural panels (bulkheads, floor, wheel arches) and where they run alongside existing vehicle wiring. Plan to keep 12V leisure wiring physically separated from the van's OEM wiring where possible.

Cable Trunking

Plastic cable trunking (also called raceway or dado trunking) is the quickest way to run multiple cables along a flat surface in a neat, protected bundle. It consists of a base that clips or screws to the surface and a snap-on lid that covers the cables.

When to Use Trunking

• Along the lower walls of the van, running from the battery area to appliances
• Under fixed furniture where cables are not accessible for inspection
• In the ceiling void above cladding
• Anywhere multiple cables run a similar route

Trunking Sizes

Choose trunking sized for the cables you will run, with at least 30% spare capacity for future additions:

Fixing Trunking

Self-adhesive trunking loses its grip over time, especially in temperature extremes. Screw-fixed trunking is more reliable for permanent installations. Use short self-tapping screws into van panels, or pop rivets. In areas with cladding, fit the trunking before the cladding goes on.

Conduit and Flexible Conduit

For cables passing through walls, floors, or tight spaces, flexible split conduit (also called cable wrap or split loom) protects cables from abrasion and allows easy installation around existing features.

Split Conduit

Flexible corrugated conduit with a lengthwise slit. You press cables into it without needing to thread them through. Available in 6mm to 32mm diameter. Good for bundling cables behind panels and in engine bay runs.

Smooth-Bore Conduit

Used where you need to pull cables through after the conduit is fitted — through bulkheads, under the van floor, or through furniture. Requires threading the cable through before fixing, but provides better protection than split conduit.

Where to Use Conduit

• Any cable passing through a drilled hole in the van body
• Under-van cable runs (particularly for shore power inlet cables)
• Through the ceiling void for solar panel cables
• In the engine bay for DC-DC charger input cables

Grommets: Essential at Every Panel Penetration

Every hole drilled through a metal panel needs a rubber or PVC grommet. Metal edges are sharp enough to cut through cable insulation over time — vibration does the rest.

Grommet Types

• Closed grommets: pre-fitted around a cable at assembly time. Neat but requires removal to change cables.
• Split grommets: clip around existing cables without removal. Easier to retrofit.
• P-clips with bushings: for larger cables and bulkhead-style penetrations.

Size the grommet to the hole, not the cable. The grommet should fit snugly in the hole with the cable having slight clearance through the grommet's centre. If the fit is loose, the grommet will vibrate out.

Cable Clips and P-Clips

For individual cables running along chassis members or structural ribs, P-clips (also called cable clamps) provide a secure fixing that prevents sagging and chafing.

• Use rubber-lined P-clips for 12V leisure cables — the rubber prevents metal-on-metal contact and absorbs vibration
• Fix at maximum 300mm intervals for cables under 6mm², 200mm for heavier cables
• For very heavy cables (25mm²+), use purpose-made battery cable clamps

Cable Looming

When multiple cables run the same route for a long distance, binding them into a loom keeps the installation tidy and reduces the risk of individual cables moving and chafing.

Self-Amalgamating Tape

For a permanent, weatherproof loom, wrap cables with self-amalgamating tape. This fuses to itself without adhesive and creates a solid, waterproof bundle. Good for runs in the cab area or through wet spaces.

Spiral Wrap

Plastic spiral wrap winds around a bundle of cables and holds them loosely together. Allows some movement (useful near connectors where flex is needed) and is easy to undo. A good all-round option for dry, internal runs.

Heat Shrink Sleeving

Large-diameter heat shrink can encase a bundle of cables. Provides a very neat finish and some abrasion protection. Less flexible than spiral wrap.

Cable Ties

Use in combination with P-clips and trunking to keep bundled cables together. Use only UV-stable black nylon ties for external runs. Inside the van, standard ties are fine. Trim the tails flush after tightening — protruding tails are surprisingly good at cutting insulation on adjacent cables.

Separating Cable Types

Keep these groups separated by at least 50mm where possible, and never bundle them together:

• Solar PV cables (high DC voltage under sunlight — up to 40V) — route separately from 12V cables
• Inverter AC output cables (230V) — route in their own conduit, away from all DC wiring
• OEM vehicle wiring — keep leisure wiring away from the van's own looms
• Audio/video signal cables — route away from 12V power cables to avoid interference

Routing Through the Floor

Cables running from the battery (typically under a seat) to appliances at the front of the van often need to pass under the floor panels. Options:

1. Under the floor insulation — route cables in split conduit below the thermal insulation layer before the floor goes down. Clean and invisible, but inaccessible afterwards.
2. Along the floor edges — run cables along the van wall at floor level in trunking, covered by kickboards or furniture bases.
3. Through purpose-cut channels in the floor ply, routed in conduit and sealed against moisture.

Never run cables where they can be stood on or where heavy furniture legs will press on them.

Roof Penetrations for Solar

Running solar panel cables through the roof is covered in detail in our solar cable gland guide. The key points:

• Use a proper cable entry gland rated for outdoor use (IP67 or better)
• Route cables in conduit from the gland to the charge controller
• Never rely on mastic or silicone alone to waterproof a roof penetration — always use a purpose-made gland

Labelling

Label every cable at both ends — where it originates and where it terminates. Use:

• Heat shrink label sleeves with printed labels (most durable)
• Self-laminating cable labels (easy to apply, reasonable durability)
• P-touch/label maker tape on a short heat shrink sleeve

At minimum, label: the circuit name, the cable gauge, and the fuse rating. A simple code like "FRIDGE / 4mm² / 20A" at each end of a cable saves hours of fault-finding later.

Inspection and Maintenance

After 3-6 months of use — once the van has done some mileage — do a cable audit:

• Check every grommet is still seated
• Check P-clips have not loosened
• Look for any chafing marks on cable insulation
• Re-tighten any loose trunking lids
• Check cables near moving parts (sliding doors, seat runners) have not been pinched

FAQ

What is the best cable trunking for campervans?

Standard white PVC trunking from electrical suppliers is fine for internal use. For areas that may see moisture, use grey IP-rated trunking. Avoid the very cheapest self-adhesive trunking — it falls off in summer temperatures inside a van.

Can I use the van floor as a cable run?

Not without protection. Cables run under removable floor panels must be in conduit to protect against crushing and abrasion. Cables run in a channel cut into fixed floor ply should be in conduit and sealed.

How do I run cables through a van bulkhead?

Drill a hole slightly larger than your cable bundle, fit a rubber grommet or IP-rated bulkhead gland, and run your cables in split conduit. For multiple cables, consider a multi-way bulkhead gland — available in sizes from 2 to 8 cables.

Do I need separate trunking for positive and negative cables?

No, but keep AC and DC cables separated. Running 12V positive and negative in the same trunking is fine and conventional. Running 230V AC cables in the same trunking as 12V DC cables is not recommended — use separate conduit for the AC side.