Standards for vehicle electrical systems: What is required and why
Answered briefly

For recreational craft in Europe, Directive 2013/53/EU on recreational craft applies; technical details are specified in harmonized standards — ISO 10133 for direct current up to 50 V, ISO 13297 for alternating current. Six basic principles run through: fuse every wire close to its source, select the fuse according to the wire gauge, make supply and return leads equally strong, separate AC and DC, interlock power sources, and document tests.

Standards are not bureaucracy; they are compiled incident reports. Anyone who understands the specific event for which a requirement was written can apply it meaningfully in their own design — rather than just checking it off or ignoring it.

Which regulations apply

For recreational craft in Europe, the legal framework is the Recreational Craft Directive 2013/53/EU. It formulates essential safety requirements but no technical details. The details are contained in harmonized standards, the application of which is voluntary — however, anyone who complies with them can assume they are meeting the Directive's requirements.

Standard Subject
ISO 13297:2020 DC and AC systems on board, combined in one standard. Since December 2020, this has replaced the previously separate ISO 10133 (DC) and the older version of ISO 13297, which applied only to AC.
ISO 8846 / ISO 8849 ignition-protected equipment, bilge pumps
ABYC E-11 US-American counterpart; not authoritative in Europe, but often technically helpful

Vehicles on the road fall under different regulations. The physical principles — fusing, cross-section, separation, corrosion — are the same, but the formal requirements are not.

The DC side

The DC part of a system seems harmless because the voltage is low. This is deceptive: a battery bank can deliver four-digit currents in the event of a short circuit, and the resulting energy is enough to set a cable on fire in seconds.

The requirements therefore revolve around a few key points: every cable is protected against overload and short circuits, the fuse is located close to the source, cables are protected against chafing and mechanical damage, and connections are made so that they cannot come loose on their own.

WarningThe fuse protects the cable, not the device. It is selected based on the cross-section, not the power consumption of the appliance — and it sits as close as possible to the source because no one protects the unshielded section before it.

ISO 13297: DC systems on board (formerly ISO 10133)

What the standard requires for extra-low voltage systems — fusing, cross-sections, cable routing, disconnect devices — and how this can be implemented in your own setup. The former ISO 10133 was withdrawn at the end of 2020; the requirements for the DC side have been included in ISO 13297 since then.

Read in detail

The AC side

As soon as 230 volts come on board — via shore power, generator, or inverter — different rules apply. The reason is not only the higher voltage but the environment: conductive structures, moisture, and a person who is often standing grounded.

The central topics are the protective conductor, residual current protection, the clear separation between the sources — shore power, generator, and inverter must never overlap — and the question of how the shore power's protective conductor is connected to the on-board system. The issue of corrosion is also tied precisely to this connection.

ISO 13297: AC systems on board

Protective conductor, residual current protection, source switching, and labeling — the requirements for the 230-volt side and their rationale. Since the 2020 version, the same standard also regulates the DC side, which was previously in ISO 10133.

Read in detail

Galvanic corrosion

Two different metals, an electrolyte, and a conductive connection create a battery cell — and a cell produces current as long as one of the metals dissolves. In water, all three prerequisites are permanently present.

At the berth, a fourth is added: the shore power protective conductor connects the underwater fittings of all connected boats to each other. This creates a common cell across the dock — and the anodes of one boat may, under certain circumstances, end up protecting the neighboring boat.

Galvanic corrosion: Causes and countermeasures

How the cell is formed, why the protective conductor extends it across the entire dock, and which countermeasures are actually effective.

Read in detail

The shore power connection

The socket on the dock is the part of the system that you didn't build yourself but use anyway. Reversed live and neutral conductors, a missing or interrupted protective conductor, a socket without residual current protection — all of these happen, and none of them are visible when plugging in.

NoteA permanent display on board that signals reverse polarity and a missing protective conductor is the simplest effective measure of all. It costs little and checks automatically every time you plug in.

Testing shore power: Polarity and protective conductor

What can be wrong with a dock socket, how to recognize it before plugging in, and which on-board display handles the testing permanently.

Read in detail

Six principles that apply everywhere

  1. Every cable is fused, as close to the source as possible.
  2. The fuse matches the cross-section, not the consumer.
  3. Both live and return wires are routed, with the same cross-section — no ground return through the hull or frame.
  4. DC and AC remain separated — separate conduits, separate terminals, clear labeling.
  5. Sources never overlap — shore power, generator, and inverter are interlocked against each other.
  6. What has been checked is noted — without a record, there is no proof and no reference.

Typical mistakes

Shore power connection unit LAE 232

philippi

Shore power connection unit LAE 232

€320,00
€320,00
Grid control panel LAR

philippi

Grid control panel LAR

€42,00
€42,00
Galvanic Isolator GI

philippi

Galvanic Isolator GI

From €129,00
From €129,00
M88000355

Mastervolt

Isolation Transformer Mass GI 3.5

€1.332,80
€1.332,80

Fits with that

Distribute and protect power: Control panels, fuses, cross-sections

Cable cross-sections, fuse ratings, and the construction of a distribution board — the calculation methods that turn a consumer list into a distribution.

Vehicle Electrical System Refit: Planning, Implementation, Troubleshooting

From evaluating existing systems to troubleshooting with a multimeter — the order, budget, and pitfalls of renovating existing structures.

Understanding the Vehicle Electrical System: Structure, Voltages, Terminology

12 V or 24 V, voltage drop, consumer balance, and grounding — the parameters upon which all other technical areas are built.

Entwicklung philippi — Entwicklungsabteilung, philippi elektrische systeme GmbH

Verfasst und fachlich geprüft von der Entwicklungsabteilung der philippi elektrische systeme GmbH in Remseck am Neckar. Ändert sich eine Norm oder eine Produktspezifikation, wird der Beitrag überarbeitet und das Prüfdatum aktualisiert.

Entwicklung, Fertigung und Prüfung von Bordnetzkomponenten seit über vierzig Jahren

Erstellt 09.09.2026 · Zuletzt geprüft 09.09.2026

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