Welcome to my blog about Live Magic, a Vivacity 20 yacht based on the south coast of England. Here I will update on trips, maintenance and any projects being undertaken.

Friday, 8 April 2011

Adding Shore Power

Hi all, this weekend I installed shore power on my little 20’ Vivacity and thought I would share the experience in case it’s useful.

First, I used the black foam which accompanies the flush socket as a drilling guide. This foam is to help waterproof the installation but is useful for drilling as it’s the same size as the socket. I drew around the inside with a marker and then drilled many small holes around the edge.
Next, I wrapped tape around a coping saw blade and cut between the holes
Once the hole was cut, I used a round and flat file to neaten the hole and adjust to the correct size. Here I kept it as tight as possible to ensure a more waterproof fitting. Once the socket fitted, I installed it with sealant on both sides of the foam padding and fixed in place with 4 3.5mm bolts.
Next, I wired up the consumer unit, having determined the most suitable place for it inside the boat. Wires were all stripped and tinned prior to fixing in place to try to prevent corrosion. I used a 32A cable from the socket to the CU, although 16A would have sufficed, all other cabling was 16A including the premade shore power cable. When inserting into the CU, an IP68 grommet was installed on each cable to ensure a watertight seal. The consumer unit purchased includes a double pole RCD to ensure power is completely cut when necessary rather than just cutting the live circuit. Two separate MCBs (Miniature Circuit Breakers) are also included giving two separate circuits within the boat. This will be plenty for my little boat which will have 2 sockets and a permanent battery charger.
Next, the wires were installed with the incoming power line connected to the earth bar at the top of the unit and the live and neutral both going to the RCD. The other two cables shown in the picture are for sockets, so both lives go to the smaller MCB and neutral to the neutral bar. Earth, as always, fitted to the earth bar. The spare MCB will be used in future for a permanent fixed battery charger.
Once all wiring was complete, the unit was put into place. This is done after wiring because boats are difficult to get around. This is also the reason I connected the CU end of all cables first, so that cable can be fed back through the boat to the various sockets from there. I have left some slack in the cable to allow some movement for when I fit the charger.
Next, the sockets were installed in some high/dry places which are convenient to get to. In my case this is the end of the lockers in the cabin. Wires were again tinned and screwed in then the sockets fitted into the boxes.
After the sockets were in, the incoming socket was wired up without the shore power cable connected. This was done last so ensure there was no chance of accidentally powering up the system before it was finished.
Finally, I plugged in the shore power and switched on the RDC and MCB and connected a radiator which all worked first time. As mentioned above, I will soon be fitting a permanent charger but will also be fitting a 240v lamp between the earth and neutral wires before the RCD. This will light up if the power in the marina has earth and neutral installed backwards and will be a warning not to switch on the RCD. This is optional and probably unnecessary for UK marinas, but apparently can happen abroad so is a worthwhile investment.

I hope this is useful to anyone fitting shore power, as always I’m interested in any feedback you have.


  1. Just contemplating buying my first boat...and found this walk through most helpful (found it via a forum on YBW). Your website is now bookmarked; I dare say it'll come in very handy in the future!

  2. Thanks for the comment. In addition to the above, to be fully compliant with euro regs you'd need to swap the main RCD (the big one) out with an RCBO like the one at http://www.tlc-direct.co.uk/Products/CPBR402.html. This gives better over-current protection, although I myself have not yet done the swap. Good luck with the boat, do you know what you're getting and where you'll be?

  3. Hi Dave - I have been thinking about doing this myself for our yacht but wonder if it is necessary to fit a Galvanic Isolator. Is this something you had considered or do you not think it necessary until adding the battery charger to the system.



    1. Hi Perri, sorry for taking a while to reply. The isolator is not something I required on my boat since I don't have an engine or fittings connected to earth. If you have these it may be a good idea, what's your setup?