Caravan park pitches and marina berths are two of the few places in BS 7671:2018+A4:2026 where a PME earth is banned outright. Section 708 (caravan and camping parks) and Section 709 (marinas and similar locations) both say the protective conductor of a socket-outlet circuit supplying a pitch or berth must not be connected to a PME terminal, which is why nearly every park you walk onto runs its pitch supplies on a TT system with local earth electrodes. Add BS EN 60309-2 outlets, an individual 30 mA RCD and overcurrent device on every socket, and you have most of the special rules. This guide sets out the rest, and how to test and record them.
- Sections 708 and 709 are special locations in Part 7 of BS 7671:2018+A4:2026. The general rules still apply; the section rules modify or add to them.
- PME (TN-C-S) earthing must not be used for caravan pitch or marina berth socket-outlet circuits. The usual answer is a TT arrangement with an earth electrode.
- Every pitch and berth socket needs its own 30 mA RCD and its own overcurrent protective device. Shared RCDs are not acceptable.
- Sockets are BS EN 60309-2 (blue 16 A or 32 A industrial type), minimum IP44, mounted 0.5 m to 1.5 m above ground on a caravan pitch, and above the highest water level at a marina.
- Underground cables on caravan sites should be buried at least 0.6 m deep and kept clear of pitches where tent pegs and ground anchors go in.
- IET GN3 recommends an annual EICR for caravan parks and marinas. The caravans themselves are a different section (721) and a different job.
What do Sections 708 and 709 actually cover?
Section 708 applies to the electrical installations of caravan parks, camping parks and similar locations, including the supply to caravan pitches, tent pitches and mobile homes. It stops at the caravan's inlet. The caravan itself, its wiring and its socket-outlets are covered by Section 721 (electrical installations in caravans and motor caravans), and a residential park home that is permanently connected is treated as an ordinary dwelling.
Section 709 applies to marinas and similar locations, which means the fixed installation that supplies pleasure craft and houseboats at a berth. It also stops at the shore supply outlet. The boat's own wiring is outside BS 7671, though inland waterways and marine bodies have their own guidance for it.
Both sections have the same underlying worry: the user connects a metal box on wheels or a metal hull to your supply with a trailing lead, then stands on damp ground or in a wet boat and touches it. A fault that would be a nuisance in a dry kitchen becomes a fatal shock path, so the earthing and RCD rules are stricter than anywhere else outside Section 701 bathrooms and Section 702 pools.
Why is PME earthing not allowed for pitches and berths?
On a PME supply the neutral and earth are combined in the supply cable. If that combined conductor breaks, the neutral current has to return to the transformer through whatever earth path it can find, and every earthed metal part connected to the PME terminal rises towards line voltage. In a house the potential is held down by bonding and the fault is contained inside a building. On a caravan pitch there is nothing to hold it down: the caravan chassis, the steps and the gas bottle cage all sit at the fault voltage while the occupant stands on wet grass in bare feet.
Regulation 708.411.4 therefore requires that the protective conductor of each socket-outlet circuit supplying a pitch is not connected to a PME earthing terminal. Regulation 709.411.4 says the same for marinas. The site building, the shop and the shower block can stay on the PME supply as normal, because they are ordinary buildings with bonding. The pitch and berth circuits are separated from that earth and given a TT arrangement with their own electrode.
That electrode has to do real work. On a TT system the disconnection is by RCD, and the design condition is Ra × IΔn ≤ 50 V. For a 30 mA RCD that allows an electrode resistance of up to 1,667 Ω in theory, but the IET guidance is to aim for a stable value of 200 Ω or less, because a rod that reads 800 Ω in September can read 1,500 Ω after a dry July. If you are unfamiliar with the TT calculation, the guide on Earthing Arrangements Explained: TN-S, TN-C-S and TT covers it, and Earth Electrode Testing for TT Systems: Methods and Limits shows how to measure the electrode.
Where the site is fed at TN-C-S, the usual design is a PME intake for the buildings and a separate TT distribution for the pitch circuits, with a metallic separation between the two. The PME earth and the TT electrode must not be connected together, and you should look for accidental links through metal conduit, armoured cable armour or shared trunking. A steel wire armour that is earthed at the PME end and also bonded to a TT pitch pillar is exactly the kind of thing that fails a park EICR.
What are the socket-outlet rules on a caravan pitch?
Section 708 is specific about the outlets, and this is where most observations come from.
| Requirement | Caravan pitch (Section 708) | Marina berth (Section 709) |
|---|---|---|
| Socket standard | BS EN 60309-2, minimum 16 A | BS EN 60309-2, minimum 16 A |
| Ingress protection | IP44 minimum | IP44 minimum; higher where hosed or splashed |
| Mounting height | 0.5 m to 1.5 m above ground | Above the highest water level; guidance is not less than 1 m, with a lower limit of 300 mm accepted on floating pontoons |
| RCD | One 30 mA RCD per socket-outlet | One 30 mA RCD per socket-outlet |
| Overcurrent protection | One device per socket-outlet | One device per socket-outlet |
| Reach | Located so a 25 m caravan supply lead reaches the pitch | Located so the shore lead reaches the berth without crossing water |
| Earth | Not PME; TT with electrode is the norm | Not PME; TT with electrode is the norm |
Each pitch gets at least one outlet, and it must be within reach of the caravan's supply lead. Section 721 limits that lead to 25 m of flexible cable, 2.5 mm² for a 16 A supply, so a pillar sited so the lead has to be extended or joined is a design fault, not the user's problem. Sockets on a pillar should be grouped so that no more than four outlets share one enclosure, which keeps the number of caravans affected by one pillar fault manageable and stops leads crossing each other.
The RCD requirement is often misread. It is not enough to have one 30 mA RCD covering a pillar of four outlets; each socket must be individually protected so that a fault in one caravan does not trip its neighbours. In practice that means a 30 mA RCBO per outlet, or an RCD per outlet feeding a fuse or MCB. On older sites you will find a 100 mA delayed RCD at the pillar feeder with a shared 30 mA RCD across all the sockets, which was never compliant and should be coded. A shared 30 mA RCD is usually a C3 if it operates correctly and a C2 if it does not, but any outlet with no 30 mA protection at all is a C2 as the user is relying on it while standing outdoors.
For three-phase sites, 32 A or 63 A five-pin outlets for large touring units and mobile catering follow the same rules; see Three-Phase Testing Basics for Domestic Electricians for the testing side.
What does Section 709 add for marinas?
Marinas keep the pitch rules and add the water. Regulation 709 identifies the same external influences as caravan parks plus AD (water), AF (corrosion) and AJ (mechanical movement), and the design has to answer each of them.
Cables on pontoons flex constantly as the structure rides the tide, so ordinary PVC cable in fixed conduit fails at the joints. The accepted choices are flexible cables with a thermoplastic or elastomeric sheath, mineral-insulated cable or armoured cable, installed with enough slack at every hinge and ramp to allow for the full tidal range. Cables must not be run where they can be damaged by mooring lines, and overhead lines are not permitted over the water. A floating pontoon feed that goes rigid at the shore junction is one of the most common failures you will see.
Corrosion hits the connections. Service pillars should be stainless steel or reinforced polymer, with marine-grade glands and a drain point, and every earth connection should be a corrosion-resistant fixing. Copper earth electrodes in salt water need checking for electrolytic loss, and in a saltwater marina you should never rely on the steel pontoon structure as the electrode because it may be sacrificially protected and deliberately isolated from the shore earth.
Mounting height is set by the water, not the ground: the outlet has to stay out of wave splash and above the highest expected water level, with the guidance giving 1 m as the working figure and 300 mm as the lowest acceptable height on a floating pontoon that rises with the water. Outlets on fixed quays need to allow for spring tides and flooding, and a berth outlet that has been submerged even once should be replaced rather than dried out.
Section 709 also allows for a supply through an isolating transformer on the boat to break the earth connection and stop galvanic corrosion between hulls, but that is on the boat side. On the shore side you provide a TT earth and the 30 mA RCD per outlet as for a caravan pitch. Electrical Safety First has published guidance on boat shore supplies that is worth handing to the marina operator when you explain why their sockets are being coded.
How should underground and overhead cables be run on a park?
Section 708 says cables should be buried outside any pitch or area where tent pegs or ground anchors are likely to go in, at a depth of at least 0.6 m, and where that is not possible they should be given additional mechanical protection. Marker tape and a surveyed route drawing should be part of the site records, because the biggest risk to a park cable is the groundsman with an auger.
Overhead lines are permitted but constrained. Where vehicles move underneath, the minimum clearance is 6 m; elsewhere it is 3.5 m, and poles have to be placed away from pitches and roadways to avoid being struck. Overhead lines with insulated conductors are preferred and bare conductors over pitches are not acceptable. A pitch supply from an overhead line still needs the TT earth and individual RCD protection.
Site distribution boards and pillars should be lockable, with the RCD test button accessible to the user without opening the live compartment. A pillar that has to be opened with a screwdriver to reset an RCD is a design observation because the site warden will end up leaving it open.
How do you inspect and test a caravan park or marina?
Treat it as a commercial EICR with a special location overlay. GN3 recommends a one-year interval for caravan parks and marinas, and site licence conditions from the local authority usually require evidence of an annual inspection. The scope needs agreeing with the operator, because a 200-pitch park may have 50 pillars, several kilometres of cable and a handful of buildings, and you will not test every outlet in a day. Record the sampling plan and the limitations on the certificate, as described in EICR Sampling and Limitations Explained: Extent, LIM and N/V.
At the origin, confirm the earthing arrangement for the site buildings and separately for the pitch distribution. Measure Ze at the intake, then measure the TT electrode resistance for the pitch supplies with an earth electrode tester, not just a loop test through the supply. A loop test on a TT system gives you the whole loop including the DNO earth path and can hide a poor electrode. Record the electrode resistance and the season. For each sampled pillar, test insulation resistance on the feeder at 500 V, continuity of the protective conductor back to the electrode, polarity at every outlet on the pillar, Zs at the outlet, and a full RCD test on every 30 mA device: 1 × IΔn should trip within 300 ms on a TT system and the ramp test gives you a health check on a device that lives outdoors.
Then look at the things a meter will not show you. Cable entries with no gland or with the gland cut off, pillars with water inside, outlets with the flap spring gone, earth electrodes with the clamp corroded off, and pitch leads coiled around the pillar base are the standard observations. Confirm that the PME and TT earths are kept separate by disconnecting the pitch earth at the board and checking there is no continuity to the PME terminal. That single test finds more faults on parks than any other.
For marinas add a visual check of every hinge and ramp cable for chafe, confirm outlets sit above the highest water mark, look at the pontoon steelwork for stray current corrosion, and check for shore leads that have been modified with domestic plugs. A boat supply from a BS 1363 socket in a shed is not a berth supply and should be coded as such.
What are the most common codes on parks and marinas?
Shared RCD protection across a pillar of outlets is the most common finding on sites built before the individual-RCD rule was strict. Code it C3 where a working 30 mA RCD covers the outlets, C2 if the RCD is faulty or slow. No 30 mA RCD at all on a pitch outlet is a C2. A pitch circuit found connected to the PME terminal is a C2, because the danger relies on a supply fault that the user cannot see coming. A missing or unreadable electrode resistance with a TT arrangement is an FI until you have measured it, then a C2 if the value cannot hold Ra × IΔn under 50 V. BS 1363 outlets used for caravan supplies, outlets below 0.5 m or below the water line, cables buried shallow under a pitch, and overhead lines below the clearance heights are all C2 in normal circumstances. Pillars with water ingress and corroded live terminals are C2 or C1 depending on whether a live part is accessible.
The guide at Outbuilding and Garden Supply: SWA, TT or PME Earth? covers the same TT versus PME decision on a smaller scale, and Hot Tub and Swimming Pool Wiring: Section 702 Explained covers the pool at the leisure park, which is a different section again.
How Certio helps
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