Sunday, 8 February 2015

Electrical installation begins......

This weekend as planned I started on the installation of the 240v shore power system, not an exceptionally difficult job but one that needs some thought and planning.

Most of the parts needed are pretty much similar to domestic components except for the cable, and the use of a garage consumer unit and the additional installation of a Galvanic Isolator on the earthing circuit.

I was a little surprised at the time it took to decide on the first job which was where to site the inlet socket, this is where the shore power will connect to the boat.

After some time I decided on using a cubby hole in the cockpit which will ensure the plug and socket will stay dry most of the time, although the connections are waterproof anyway.

I also found somewhere else to clean!!

Once cleaned I managed to route the cable from where I intend to mount the consumer unit, so the next job was to cut a hole then connect and mount the socket.

Once completed the rest of the work was all inside which gave me the opportunity to warm up a little.

As I mentioned earlier the Consumer unit I am using is intended for use in an outbuilding or garage so is better suited to a marine environment as it is IP55 rated and has an RCD fitted.

It has 3 breakers, 6, 10, and 16 amp, the 6 amp will be used to wire in the battery charger, the 10 amp will be for the hot water calorifior, and the 16 amp will be for the on board plug sockets.

I am not an electrician but have some experience with this type of installation, so as always I wanted to confirm that what I was planning to install was going to be suitable and safe and came across an article which had the exact wiring diagram for the plan I was using. (thanks to Colin Shead)

The cable I am using is different from domestic 2.5mm solid core, H07RNF is the most suitable cable to use although Arctic cable is commonly used.

This cable is a little more expensive but is extremely flexible so good for tight spaces and less susceptible to chaffing.

The main difference with a marine installation is that the use of a galvanic isolator is advised, which without getting too technical will prevent electrolysis from destroying underwater stern gear.

It took most of the day to get the basics completed, which was to install the inlet socket, consumer unit and Galvanic Isolator.
Next will be the wiring of the sockets (3 double gang and 3 single gang throughout the boat) once this is complete I will start looking at new batteries, charger and battery cables.

I have also posted some PDF files which might be useful to anyone undertaking a similar job.

The first is where I found the wiring diagram and is an article by Colin Shead, the second is a magazine article with some useful tips.

Marine electrical tips

Shore power installation


  1. you have shown the points very clearly. this is going to help me in many ways...
    handyman Dubai

  2. Thank God . . . I am female and am trying to understand exactly what is required to fit shore power on a small boat. This has made it so simple and understandable instead of electrician talk!!!! which I found difficult to figure out!!!

    I can now get on with fitting it knowing what I need to buy and what amps etc!!!! Instead of researching lots of article and getting more and more confused!!

    So once again thank you for taking the difficulty out of this with your knowledge of how to!!!!