what life offers a dedicated hobbyist on the water ..

Compared to sailors, we motorboats have an advantage: we produce our own electricity on the way. In the evening in the harbor it looks different, and depending upon extent of the comfort equipment we need 230V from the respective Marina: by land connection. The latter has, if done correctly, as much in common with a simple extension cord as my boat has with a cruise ship. Here are the details.

To prevent the outcry right away: Electrical cables are potentially life-threatening and something for experts! My point is to put together what needs to be done, not who does it. This should be more a guide for the order for the shore connection to an electrician than a "now I help myself"! And one more thing: even if the data are collected with the greatest care, I am and will remain an amateur This is a regrettable individual opinion. The opinion of a trained electrician always stings!

Most of the information about the shore connection on pleasure boats is regulated by DIN EN 60092-507 Electrical installations on ships (part 507: yachts, with costs). But let’s start at the beginning. And we shimmy along the cable from the marina to the consumer. (Large yachts, which have to be supplied with 400V three-phase current, are excluded from the following consideration, and I concentrate on standard 230V supply.)

Plug systems at the shore connection

On the marina side, there is probably only one system left in Europe, the CEE plug according to IEC 60309, in blue (200-250V). Compared to the typical household system "Schuko plug" (SchuKo = protective contact) CEE has a huge advantage. The position of the two current carrying poles L and N is unambiguous and therefore verifiable (see below). With Schuko, on the other hand, it is left to chance when plugging in which of the two wires carries the phase and which the neutral conductor. CEE is the only permissible system for shore connection in Europe. Anything else can cause questions from the insurance company in case of a claim.

exotic shore connection on an Italian Sessa

exotic shore connection at an Italian Sessa

Shore connection column in the marina Duisburg

Shore connection column in the Marina Duisburg

In the harbor you can find a socket, the shore connection cable starts with a CEE plug (Amazon link). The latter has a leading PE pole, so the protective conductor makes contact first when plugged in, due to its design. (This is the thicker, somewhat longer pole "at six o’clock", i.e. down in the middle.)

the cable at the shore connection

The cable at the shore connection must be three-pole – of course, we want to transport the protective conductor PE in addition to N and L. The standard specifies 3 x 2.5qmm stranded wire, i.e. relatively thick (and thus low-loss) wires, with max. 25m length. That’s why some cables from camping accessories are not suitable for shore connection – they like to work with 3 x 1,5qmm. This is normally sufficient from a purely electrical point of view. But this is not according to standards. And installation cable with solid conductors is of course no option at all.

In terms of material, besides the usual, relatively inexpensive rubber cable, there is a very interesting alternative that I opted for: PUR cable (polyurethane). It is more dimensionally stable and can therefore be wound up better. It is more resistant to environmental influences (water, oils, but also friction) and more "slippery". So, for example, it is easier to pull around corners without damage. My shore connection cable has incorporated glass fibers, which makes the cable a bit ugly to work with, but extremely tensile resistant. There is the cable as meterware under the keyword "construction site cable" for example on eBay for ca. 2 EUR per meter (Amazon link).

Wherever stranded wires are processed, ferrules (Amazon link) must be used (VDE 0100-520 section 526 says that soldered connections should be avoided, and ferrules are the most sensible alternative to this).

"Construction site cable" for the shore connection

outside glass fibers, inside stranded wire, 2,5 qmm

outside fiberglass, inside stranded wire, 2,5 qmm

The finished shore connection cable (right plug, left coupling)

the finished shore connection cable (right plug with leading protective conductor, left coupling)

Cable length

Remains the question of length. Maximum permissible is 25m, this is already quite unwieldy and mostly unnecessary. I have therefore divided my cable and now have two sections with 9 and 16 meters on board. (By the way, this is formally UNACCEPTABLE to split the cable at the shore connection – it must be a continuous line from the marina to the boat.)

Normally I get along well with the 9 meters, on remote moorings I can then use the 16m or even both instead. Since a shore connection cable always consists of a plug and a coupler (just like an extension in the household), I can simply couple the two cables. Two cables of the same length makes little sense – if one is too short, so is the other one. together they do not need (and should not) exceed the maximum allowed 25 meters. But the minimum length depends of course on how far the shore connection is installed on board (s.u.) is away from the typical "transfer point" to the jetty. At the other end of the cable is of course a suitable coupling (Amazon link).

If you are afraid that the number of free sockets in the harbor could be a problem, you can also carry a CEE-Y cable with one plug and two couplings. For this you have to unplug someone else for a short time (and you know i.d.R. not which consumers are currently running). From now on you share the power of the fuse (s.u.). And I don’t know if a Y-cable is allowed at all. There are however in the trade, they do not seem to be completely illegal.

Shore connection boat side

With this we already have electricity at the berth – now it has to be put on board. The simplest (and correct, according to standards) is a fixed CEE-coupling. These are available both as a surface-mounted (under-cabinet) and as a built-in version (Amazon link):

Shore connection boat side ready mounted

shore connection on boat side ready mounted

CEE couplers have a spring-loaded cover that works together with a latch on the CEE plug as a locking device. A CEE-connection is therefore tension-stable, and the cover must be unlocked via a small pressure lever before the connection can be disconnected again.

Especially on American boats you will often find different plug systems instead of CEE (if the boat was equipped with a country-specific shore connection before export). The trade also sells appropriate adapter cables from CEE to these American standards. For a new construction of a shore connection according to VDE this is not an option. I also give to consider that a freshly imported American boat may have 110V consumers on board. You can counter this with a transformer ("Stepdown Converter"), which reduces the usual 230V to 110V – but from the point of view of the shore connection, this is also simply a consumer (then the only one).

With it we would have the current now on board. Again, all wires are stranded, also here mind. 3 x 2.5qmm, and all wires in installation tubes (or otherwise protected) and fitted with ferrules.

Circuit breaker ("fuse")

Next we want to protect the shore connection of the boat – with a circuit breaker, vulgo a circuit breaker. He must be switch to two poles, i.e. disconnect both N and L, and must not disconnect PE. two-pole circuit breakers are rather rare (but they do exist: Amazon link), so you can take a three-pole one and run PE past it, or connect two single-pole circuit breakers with a short rail so that they trip at the same time (but they must be designed for that).

Small distribution board with circuit breaker

small distributor with circuit breaker

More exciting is the question of power. At 16A is the upper limit (Amazon link). But that makes a good 3,5 kW at the shore connection and is enough for hotplates, fan heaters, air conditioner, hair dryer, etc. (even if not at the same time). The problem is that the fuse of the marina is most likely smaller dimensioned and therefore triggers first. This is especially stupid if the fuse box is locked at night and/or on weekends. Then it goes off only on Monday morning again with current. So if you really need the shore connection only for the charger, the 150W travel kettle and a cell phone charger, it is a real option to install a 2A circuit breaker (Amazon link). The triggers in almost every case before that of the marina. Then you can not even vacuum in the home port (2A)

So be aware of your expected maximum current and dimension the fuse in the shore connection accordingly – the easier you will have it in unknown ports.

Personal protective switch (RCD)

Next comes the most important thing in my eyes: the personal protection switch (Amazon-Link), colloquially also called FI-switch or residual current switch. Its function is quickly explained in simplified terms: in a "healthy" circuit, just as much current flows to the consumer as flows away from it. If, on the other hand, there is a fault – e.g. due to a damaged insulation – a part of the current flows off at this point (worst case by a grounded person) and not back through the line. An RCD measures the difference between the outward and return paths and disconnects both poles immediately as soon as a difference of more than (i.d.R.) 30 mA exists. If a person gets "wiped", an intact RCD trips so quickly that there is usually no danger to life. Especially in such a moisture-prone environment as a boat, an RCD is indispensable. And it is mandatory in the shore connection anyway.

left FI, right 3-fold circuit breaker, below mains control lamp

left FI, right 3-fold circuit breaker, below mains control lamp

Circuit breaker and circuit breaker for personal protection can be placed in a small distribution board (Amazon-Link). A single row with 6 modules is sufficient to accommodate the 2-3 circuit breakers and the ground fault circuit interrupter. There are also RCDs and circuit breakers as a combined module, which then takes up a little less space. They sail under the RCBO designation:

Then remains even in a small distributor enough space for separate circuit breakers for the individual circuits, if desired. This one here (Amazon link) is such a one: 2-pole, 16A line protection and 30mA fault current, good 30 EUR. It does not get much easier.

In both mentioned installations of the shore connection the PE (protective earth) is not considered – it must not be separated by a three-pole circuit breaker, and with the FI it must not be considered at all. (Because otherwise bspw. current could flow through a human into the PE conductor without tripping the RCD).

You can also shortcut the process a bit and consider pre-wired shore connection boxes (Amazon link). They are more expensive, but save a lot of work.

galvanic corrosion

Here now something comes into play, which exists in this form only on the boat. Background is the galvanic corrosion. Simplified this means that from possible conductive bank components (e.g. sheet pile wall or even the neighboring steel boat), the conductive components of the boat in the water (bspw. the drive or outboard motor) and the protective earth conductor in the shore connection, which connects the two, a huge battery is created. This means that the least electrically valuable metal, i.d.R. the sacrificial anodes and then the (aluminum) drive, decomposed. The problem arises in full beauty only if the protective conductor is connected via the shore connection and any charger with the battery ground and thus the engine/drive. This is not the case with all chargers. If, it degrades in the shortest time the sacrificial anodes and then more valuable components, primarily the drive.

galvanic isolator vs. Isolating transformer

To prevent galvanic corrosion, there are two possibilities. The easier and cheaper way is a galvanic insulator or "Zincsaver". It is looped into the protective conductor of the shore connection and separates it in such a way that it continues to fulfill its protective function, but prevents galvanic currents. It is indestructible except by lightning (and even with that it is not reliable). Its functionality is trivially measurable: with a multimeter in diode test mode, the voltage in both directions should be set to approx. 0.9 V rise and stay there; then short-circuit the isolator (discharge capacitor) and repeat – it must start again at 0. So there is nothing against a used device. I paid 45 EUR for a 30A ProMariner Zincsaver on eBay – that’s cheaper than a set of anodes.

galvanic isolator in the shore connection

galvanic isolator in the shore connection

The alternative is an isolating transformer. This forms a protective separation in the shore connection between the marina power system and the onboard power system. This is the conceptually cleanest solution – but also heavier and more expensive.

Mains indicator light in the shore connection

And also the next (and last) object is something specific: a power indicator light. This is also mandatory and in the comfort version takes over several control functions at once. On the one hand, it detects when N and L have been reversed. What can only happen with a pure CEE installation if someone has made a mistake. But if you build an adapter from Schuko to CEE and connect the boat to a normal Schuko socket, it is again up to chance which conductor gets N and which gets L. This is irrelevant for the electrical function, but it is only proper if the wires (and wire colors) intended for L also carry L.

On the other hand, the control light checks if the neutral and PE are connected properly. I decided to use this one: charge indicator light from Philippi. Misoperation impossible: if it lights green, you have power and everything is fine. And with 20 EUR I think there is no question to ignore the standard here.

From now on it gets boring – now come the consumers, in my case these are normal wet room sockets (3 x 2 on 6 meters boat length, which is probably a bit overengineered). However, again, make sure that the wiring is 3x 2.5qmm with ferrules and in installation tubes (or otherwise protected).

special risks in the context of shore connection

If the installer takes these guidelines to heart, the newly installed shore connection does not pose any unnecessary risk, and in the event of damage there is little discussion with the insurance company.

But I have one more important aspect: if you use a generator or a converter on board, in order to be able to use 230V consumers away from harbors, you have to connect especially carefully. It must be technically impossible for the 230V of the generator / converter to get onto the shore connection. Best case only a countless fuses flies off, if one tries to supply the Marina with current. Worst case a human being touches the CEE plug of the shore power cable, where (as in any plug) the poles are not protected against contact. Such mixed environments, best still with uninterruptible power supply, are something for advanced users!

24 Thoughts on " Shore connection: how to do it right "

  1. peter28hb20. December 2015 at 3:14

This post has answered several questions for me, because of which I have already searched many forums. Many thanks! But the practical execution I will surely leave to an electrician.

You write of a \"a CEE shore connection submount plug with spring-loaded protective cap\", but you picture an outlet and not a plug. I almost made that mistake with the electrics too, doesn’t do well when you plug the power cable into the socket on shore to \"sharply\" plug in hand to boat goes to plug it in.

  1. admin Contributor 17. February 2016 at 10:50

You are of course right& I have deleted the photo and will replace it with one of a plug – the pictured CEE mounting socket is not needed by anyone who does not want to build a CEE power column in the marina or at home in the garage. Thanks for the hint!

  1. Stephan K.6. April 2018 at 14:55

Hi Admin,
i have a Sea-Ray 280 in Spain in the Balearic Islands. Since it is an American import boat, she has a 110V circuit (and 12V). Kohler generator, microwave, fridge, ceramic hob, hot water boiler – all with (as far as I know) 110V. The shore connection is 230V. Unfortunately the air-conditioning only works with shore connection . However, I would like to install a Nespresso coffee machine (220V – ca. 1700W) and run the air conditioner on board also at anchor (not only in port).
It would be nice if someone could help me there. The Spanish electricians think the effort is much too big…..

thank you for this article, since I am a professional I will try to install it myself. I would like to ask one more question though: Is the Zinc Saver also advisable for a boat that is operated exclusively in fresh water (Lake Constance)??

Best regards! Timo

  1. Helmuzt Gebauer25. October 2017 at 10:43

Hello Timo. For galvanic corrosion, the electrolyte (i.e. the liquid) between the two metals just needs to be conductive. Lake Constance water is also conductive.
She. The highly recommended book \"Elektrik auf Yachten\" by Michael Herrmann. (It’s more for us \"professionals\").

Hello Timo,
I can not answer the question very well. Certainly the problem of galvanic corrosion is greater in salt water, but even fresh water – at least here our Rhine water – I consider contaminated enough to be conductive and to represent a battery with the countable sheet pile walls.
The clean water of Lake Constance is certainly less critical. On the other hand, the current has all the time in the world if you want to be connected to the charger 24/7 – "a little" current flow is enough then.
I would also install it in freshwater, but I’m also pretty wimpy.

thanks for the quick reply! I’m also more for the safe solution and one season is quite long, so I will have a look for a Zincsaver.

Best regards! Timo

  1. Timo14. June 2016 at 15:04

in the meantime I have built myself a distribution box, using many of your ideas. However, I went for a 2-pole RCBO and installed 3 Schuko sockets with child protection and flap directly into the distribution box. The land cable is a 15m 2,5² PUR cable with CEE plug and built directly into the distribution box. I have built myself a 3-socket strip& however, much safer than the 3.99 version from the hardware store. But my boat is short and therefore don’t need sockets in the forecastle or so.
Finally I did not use a ZincSaver, because the charger I use (Ctek) is galvanically isolated and therefore no galvanic corrosion should occur. I hope the theory is not cruelly disproved by reality&

do you have maybe a sketch how all these things are built up?.
I have small boat and will like to build 230V (Schuko) 1-2 sockets.
The end users are, charger for battery 12V, small LED television, cell phone charging.
Do you have a sketch in which order all things are built?.
Shore connection boat (CEE socket) – Fi 16A/30mA – Schuko 230V?

Thanks for the explanations, but there is a mistake: According to VDE 0751… an interruption of the feeder line is z.B with extension (9 + 16m) not allowed, the cable must be led from the shore power to the ship without interruption.

Just by the way. Judging by what you see in marinas and campgrounds sometimes…

I just wonder if it makes a difference for the galvanic isolator if I connect the indicator light before or after it – behind it you would have the advantage that you can see directly if it is still working (as far as the 3V difference from PE to PE\’ are insignificant for the LED which I assume). Where does the light hang with you? Before or behind?

  1. admin author 18. October 2016 at 12:06

Hello Tycho,
the thought is good and valid – I don’t remember in which order I connected it, the boat is sold in the meantime.
But I seem to remember that the regulation states that the indicator light must be installed as early as possible. However, if the standard allows it, I would also approach it as described by you.
However, you only check the function of the galvanic insulator to a limited extent – the control lamp would then only check it for continuity, whether it is galvanically insulated, it will not find out.

  1. Tycho18. October 2016 at 21:24

the priority for me would be yes personal safety, which is why the continuity test would be the right thing to do. The galvanic isolator consists essentially of a diode, after all. Whether the things can "burn through" so that they are only conductive, I almost don’t think so. With this the continuity test should be sufficient. Will look in the standard times. I think that it is not specified more precisely, however, it would also be the better solution for personal protection reasons, since the Galvanic Isolator is also only a compromise solution.

The price of an aftermarket Zincsaver is hard to justify, considering how simple the thing is built.

It consists only of simple, but very current-resistant silicon diodes (bridge rectifier in metal housing 400V>30A). Man can buy the things at R***lt the piece for about 1.50 euros.
4 pieces are needed. There are 2 each connected in series in forward direction.
A second cascade with 2 rectifier bridges is connected antiparallel to it:

Then the whole thing looks like this as a schematic:

+(bridge 1)- +(bridge 2)-
PE-shore connection PE-ship (ground, negative pole)
-(bridge 3)+ -(bridge 4)+

Breakdown voltage: 0.7 V + 0.7 V = 1.4 V (in both directions)

Now the ship mass can charge negatively compared to the land PE by max 1.4 V, d.h. which is connected to the zinc anodes
to protect generated negative charge of the ship ground (mostly< 1V) is not discharged to the land mass,
the sacrificial anodes are spared.
Below this voltage a galvanic isolation is established.
In the event of a fault current or short circuit to PE, the Zincsaver naturally becomes conductive for both half-waves,
because there is much more than 1.4 V here. So the Fi switch or the circuit breaker can fulfill its function.
If one takes still a robust plastic housing and tidy connections, probably not more than 20 euros will be due.

well and understandably explained. Only one question remains for us: how many 220V sockets can I protect via a residual current circuit breaker? There is an opinion that for every socket in a marine distribution board there must also be an RCD, is that so? At the moment we have 4 sockets on a 30mA FI circuit breaker.

  1. admin Contributor 13. April 2017 at 12:16

Hello Thomas, I actually do not know. I haven’t gone to the trouble of installing a dedicated RCD per outlet, and wouldn’t either. I also do not see the safety advantage in it. With 4 sockets on one FI switch you are m.E. well on the way.

Thomas, only 1 RCD or RCBO is required in the system, unless there are multiple sources whose circuits may overlap. It may be that the individual circuits must be equipped with their own RCDs. For example: charger/inverter/combined unit with shore power supply, but – if too little shore power is available – generates additional AC power from the batteries to support the weak shore power. This inevitably results in at least 2 circuits at the inverter output, each of which must be protected by its own RCD. Only one of the circuits can be protected by an RCD.

To the FI switch I have also still another question: In the described constellation and set the case that I use an isolating transformer: Don’t I need another RCD (or FI switch) BEHIND the isolating transformer?? Or does the RCD, which is installed on the primary side of the isolating transformer, also protect the secondary side??

There are also circuit breakers with switched neutral (1P+N):
z. B. NiDPN from Schneider Elektrik

First of all in general: Decisive for the AC systems on small watercrafts is no longer the VDE / DIN 507, but in the context of the RCD the DIN EN ISO 13297. Does not make a significant difference in most respects, but answers some of the questions posed here, z.B. how many RCDs must be included in the system (1), the rating (30 mA), galvanic isolators (self-made is not allowed, as these things must either be equipped with self-monitoring or be certified as \"fail-safe\"). Coding in the isolators is only to prevent direct currents from "slipping through" under an existing alternating current. RCD of course behind the isolating transformer, otherwise it would have no function. According to the 507 – as far as I remember – galvanic isolators are not allowed (\"the PE must not be interrupted\"), according to the 13297 they are allowed if they are certified. My opinion: Zinc Saver are money printing machines for the manufacturers. Even the devices certified according to ISO are m.E. not safe, as the fail-safe story is a joke and devices that are marketed with monitoring in accordance with the regulations are very expensive. Isolating transformers are much safer.

there is no information in the EN ISO 13297 about the place of installation for the RCD, doesn’t it make sense to place it directly after the onboard CEE outlet?

I found it,

it is written in chapter 7.2

Circuit-breaker to be installed within 0.5 m of the source of power or, if impractical, the conductor from the source to panel-board shall be contained within a protective covering.
If the shore-power inlet to circuit-breaker exceeds 3m, additional fuses or circuit-breakers shall be provided.

Hello Andreas,
even in 2018, your article still provided valuable suggestions; so, for me at least& Thanks for the numerous tips and ideas about the shore connection. Helped me (beginner in this field) a lot in my tinkering work.

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