Short answer
Shore power supplies 230 V to the boat for charging and heating. It requires an RCD (residual current device) both on the dock and on board, an undamaged, outdoor-rated cable and a permanent installation carried out by a licensed electrician. In wet rooms, Elsäkerhetsverket (the Swedish National Electrical Safety Board) requires a permanently installed 30 mA RCD for 230 V outlets. A boat is at least as wet, and that protection is what saves lives.
What you need
| Part | Why |
|---|---|
| Onboard RCD, 30 mA | Trips on leakage current in the boat's own circuits |
| Fixed inlet with blue CEE connector | Durable and watertight, the usual standard in marinas |
| Rubber cable for outdoor use | Withstands wet, cold and being stepped on |
| Circuit breakers for each circuit | Protect against overload and fire |
| Galvanic isolator or isolation transformer | Reduces corrosion via the protective earth |
| Battery charger designed for marine use | Charges without boiling the batteries |
Safe handling
- Connect the cable on the boat first and on the pontoon last. Disconnect in reverse order.
- Don't let connectors hang in the water. Route the cable so it doesn't get pinched by the mooring lines.
- Never use power strips or indoor cables on the pontoon.
- Press the RCD test button regularly, and always when you connect for the season.
- Don't leave fan heaters or chargers unattended on a cable that gets warm.
Corrosion – the hidden cost
The shore power protective earth connects your boat to every other boat on the pontoon. Galvanic currents can then quickly eat away anodes, drive and propeller. A galvanic isolator breaks that path. Check the anodes more often if the boat is kept on shore power, see replacing anodes.
Warning signs to take seriously
Electrical faults on boats often show small warning signs before they become dangerous. Unplug the shore power and contact a qualified electrician if you notice any of the following:
- The RCD trips often, especially when it rains or when a particular appliance is switched on.
- The plug or cable gets warm, discoloured or smells burnt.
- You feel small shocks or tingling when touching metal parts, the ladder or the water.
- The sacrificial anodes are used up within a few weeks.
- There is greenish corrosion in plugs and inlets.
Also remember that anyone swimming near a boat with faulty shore power can get a shock through the water, even in fresh water. That is why it is important that the RCDs actually work. Press the test button – if it doesn't trip, have it replaced by an electrician.
Have a professional install it
Hire a marine electrician with documented knowledge of shore power for any changes to the boat's 230-volt system. Elsäkerhetsverket's (Swedish National Electrical Safety Board) rules for fixed electrical installations on land should not automatically be read as qualification rules for installations on board. The pontoon's electrical installation is a separate installation. See also the boat's 12-volt system.
Ask for a wiring diagram and a documented inspection after the work. Keep the documentation on board so the next owner or yard knows how the boat is wired and which protection devices are installed.
Frequently asked questions
Is the marina's RCD enough?
No. It protects the pontoon outlet but not always faults in the boat's own wiring. Have your own RCD on board.
Can I install 230 V in the boat myself?
Hire a qualified marine electrician for any changes to the 230 V system. The rules for fixed installations ashore and installations on board are not the same. The pontoon's electrical system is covered by the rules for shore installations.
Why are my anodes being eaten up when I'm on shore power?
The protective earth connects the boats on the pontoon and creates galvanic currents. A galvanic isolator reduces the problem.
Sources
- Checklista för kontroll av elanläggning, Elsäkerhetsverket elsakerhetsverket.se
- Elsäkerhet för privatpersoner, Elsäkerhetsverket elsakerhetsverket.se