Shore Power

lustyd

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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.
The parts required for this are detailed in the following (no longer a table as I couldn't get tables working here), some of these were available more cheaply elsewhere but these are what I bought.

Description,Shop, P/N, Qty, Cost each, Total
25m shore power cable, Marine Super Store, 07584, 1, £34.95 £34.95
Force 4 Flush Mounted Plug, Force4, 170009, 1, £19.95, £19.95
Garage consumer unit, Screwfix, 33248, 1, £39.90, £39.90
socket box, Screwfix, 28489, 2, £1.21, £2.42
13A 1 Gang Double Pole Switched Socket White, Screwfix,, 79024, 2, £1.72, £3.44
IP68 Nylon Gland White 20mm Pack of 10, Screwfix, 17058, 1, £6.04, £6.04
Arctic cable 32A, Marine Super Store, N/A, 3m, £2.50, £7.50
Arctic cable 16A, Marine Super Store, N/A, 7m, £1.50, £10.50
Grand Total £124.70
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.
Cheers
Dave
 
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sarabande

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that's exceptionally useful, as I am about to do the same on a 24ftr.
thanks.

Can you explain the bit about detecting an wrong phase supply by menas of a 240v lamp btw earth and neutral pls ?
 

lustyd

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Basically, there should be no current between those two so a lamp connecting them will not light. If someone has connected the live to neutral and neutral to live at the pontoon end then your lamp would have power and light up. Since it's before the consumer unit, you will then know before powering up anything that there's a problem. Some boats also incorporate a switch to swap the live and neutral to ensure your power is still useful if this happens.

I should mention that I'm not an electrician, this is just from research in books and online :)
 

Gadget257

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Thank you

Dave,

Very timely, you have saved me much planning time this week.

Now to make sure that I wire the RCD correctly!

Cheers,

Chris
 

lustyd

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Wiring the RCD is actually very easy, just make sure that you get a dual pole unit for the incoming power. I'd also recommend buying a decent wire stripper for the job as you'll be stripping a lot of wires.
For removing the sheath of the arctic cables I found it easiest to score the outside then use a swedish fid to push in and break it apart.
 

lustyd

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Hi guys, did either of you do this after your posts? I'd be interested in any extra tips you find while installing.
Cheers
Dave
 

Ruffles

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Be careful as I think the metal casing might suffer from salt corrosion over time? :confused:
I don't think it's a latching RCD either (could be wrong though). So if you lose power momentarily it will disconnect which is a problem if you're running a heater or dehumidifier over the winter.
This is a latching version. Not cheap. Comparable price to the consumer unit!
 

Ripster

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Great post. No mention of installing a Galvanic Isolator in your earth circuit or is that not relevant in this case or maybe OTT?
 

lustyd

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Great post. No mention of installing a Galvanic Isolator in your earth circuit or is that not relevant in this case or maybe OTT?

Not relevant on the boat as it has an outboard motor and no other fittings through the hull which will be anywhere near this circuit. Good point to mention though as others may see this post and copy it without thinking of that.
Cheers
Dave
 

VicS

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Not relevant on the boat as it has an outboard motor and no other fittings through the hull which will be anywhere near this circuit. Good point to mention though as others may see this post and copy it without thinking of that.
Cheers
Dave

The possible need for a GI should not be totally dismissed on the grounds that the boat has an outboard rather than an inboard engine.

There are several "ifs", but

IF the outboard has a DC power output capability then its structure will be connected to the DC negative and could be vulnerable

IF the outboard is left in the water
and
IF the DC negative and the shorepower earth are connected together
and
IF the shorepower is left plugged in (even though not actually in use)
 

Ru88ell

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Old topic, but thanks Dave for the first post. I think I'll copy this, but will probably use Ratio plug and socket. I'll let you know how I get on.
 

rotrax

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Great description of a job well done.

I use Towsure at Northam for shorepower stuff-their prices are much keener than the ones you quote and so far my bits have lasted four seasons and still look and work fine.

They might be worth a look for Solent based sailors.
 

lustyd

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Old topic, but thanks Dave for the first post. I think I'll copy this, but will probably use Ratio plug and socket. I'll let you know how I get on.

Blimey that is an old one! pics are on the blog in April 2011 if you need them.
 

Jaguar 25

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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.

IF you connect a light between earth and neutral, as you say if the supply is correctly connected, the light will not illuminate. However, if the neutral and earth supplies are swapped, the light will still not illuminate as it does not have a live supply unless there is a significant leak from live to earth but that is what the RCD is for.
 

rogerthebodger

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The light Earth to Neutral will show a if the live and neutral are reversed assuming that the earth in the shore power set up is OK

I have 2 Neons one live to earth (green) which should be on and neutral to earth (red) that should not be on.

If the green is on and the red off all is OK.
If the red is on and the green off, you have incoming reverse supply, L and N reversed
If nether light is on you have an earth fault i.e. the earth line in the shore power line is not connected.
 
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