Shore Power

[TwinRudders]

Hi,

I'm installing shore power on my yacht.

At the moment there is just a normal 13 amp plug in the cockpit locker which I plug into a little converter to plug in the blue shore power lead. This then feeds 240v to a couple of sockets in the saloon and aft cabin. Whilst functional I don't think this is entirely safe...also I have a battery charger to install.

So what I'm thinking is...

In the cockpit locker:
Fit a RCB switch/breaker
Possibly mount the battery charger in here as well...? Or somewhere down below
Plus a galvanic isolator? (can't seem to get the same answer twice on this - is it a good idea - as in stopping your sterngear or other things wasting away when plugged in? (sorry about my non-technical vocab..)

As far as the shore power lead is concerned I can either feed it up inside the closed lid of the cockpit locker or drill a whole and fit a socket...

I have two batteries switched by a rotaing 1 - both 2 - off switch. Would it be wise to insert a blocking diode between these two batteries?

Many thanks for any help.

Regards,

Jono

 

[aidancoughlan]

I'm a bit new to Yacht electrics, but I'm about to address the same issues myself, and am starting to pick up tips. From what I've seen & read so far I'd make the following comments

- A friend has installed an incoming marine shorepower socket in his cockpit to take the end of the lead from the marina - works well - install it near the stern if you do so its not trailing through the cockpit.

- My boat has basic shorepower where the lead goes under the cockpit locker lid to mate with another shorepower connector on a lead inside which runs to a 3-pin socket under the chart table - the locker lid leans on the cable & risks damaging it, a cockpit socket is much better.

- I asked the RCD question a while back & the response was that this should be mounted as early as possible after the lead comes onto the boat.

- You can buy the RCD and a mcb(mini circuit breaker) in a waterproof box ideal for fitting in the cockpit locker (around £60-80 in think). You can go cheaper and buy a RCD adapter at B&Q from around £10 or so which you could mount on the internal sockets for a short term solution. "Electronics Afloat" recommends this as a solution for a simple shore power setup.

- Ive opted to skip the galvanic isolator, as my boat will be on a mooring most of the time except when marina-hopping.

- The 1-2-Both-Off switch can damage your alternator if you switch it while the engine is running (current has no where to go, and blows the alternator diodes) - you can also manually paralell the batteries by accident or forget to switch them back, dragging a good battery down with a bad one.

- blocking diodes introduce a problem with a voltage drop almost up to 1 volt - this means if you alternator is supplying 14.x volts (its sensing directly off the battery on the other side of the diode), the batteries only get 13.x volts, undercharging them - one solution is to introduce another diode upstream of the diode, so the alternater sees the same drop & ups the voltage. I believe this can get expensive. Another option is to install a (relatively difficult to install I believe) alternator charger such as Adverc or Sterling to which overcomes the voltage drop as one of its benefits. (The other benefit is a 'smart charging' cycle which gets more charge into the batteries, eventually).

- Another option for split charging (the one I am taking) is a VSR (voltage sensing relay) eg. from BEP systems (google)- around £50+vat, or £90+vat when bundled with engine,domesticand paralell switches for your batteries. BEP part no 716-SQ I think. This automates the charging & eliminates the guesswork about when to paralell the batteries for charging & when to de-couple them. Theres also no voltage drop with VSR's, so no smart alternator charger required to overcome it. If you want a fancier solution, theres a thing called a Pathmaker which is a fancy programmable VSR setup. Note of caution: While VSR's seem to be getting very popular now, one user reported a problem a while back in certain circumstances where a high current could melt the VSR - do a search on the forum & assess whether its an issue for you or not & question the supplier if you feel the need.

so there ! I'm finished. But beware, a little knowledge is a dangerous thing, but I'm sure some of the more experienced members will fill in the missing or incorrect bits.

regards,
Aidan.

 

[William_H]

If there is no connection between either line neautral or earth wires of the incoming power lead to the output wires + and - from the charger and provided the only appliances you use are double insulated (plastic) then you don't need any connection of the mains earth to the ships earth or negative wiring and so don't need a galvanic isolator. Particularly if your connection to shore power is short term. You should have the RCD perhaps one of those portable ones near the socket on shore. However in installation of mains wiring may put you into the requirement for licensed electrician to inspect the system. A good reason to keep everything portable.
As for charging dual batteries from presumably a single output charger you probably have one of those dreadfull 1,2,both switches in which case charge on both position. However a Voltage sensing relay is your best bet so you can charge battery with switch in the off position. Better still replace the rotary 1,2,both switch with individual on off switches. The VSR will work on both engine generator and shore charger. regards will

 

[Benbow]

1-2-both switches are almost all make-before-break, so you will not risk your alternator by switching between batteries with the engine running.

I agree that a VSR is one of the nicest ways to handle charging to multiple batteries. However, if you are doing that, my advice would be to throw away your 1-2-both switch and replace it with 3 on-off battery switches. One for the engine battery, 1 for the domestic battery, 1 as an emergency link. That way, the normal state is with both batteries on and you need do nothing when you start or stop the engine. Simple, flexible, effective.

 

[Trevethan]

I installed shorepower on my boat about four years ago.
There are some quite good books on 12 volt power, but I found the section on 240v systems a bit weak.

The first thing I did was fit a proper marine shorepower connector to the boat to allow me to plug in a lead.

From there, I have run as sort a length as possible of armoured cable to a consumer unit comprising an RCD and 4 MCB's. We livceaboard so have more circuits than most would need. The MCBs are rated 16 amp.

I got my kit from a local electrical wholesaler for about £70. B&Q do a small unit for shed or garage with a couple of breakers that looks quite useful.

I haven't joined my shore and boat earth systems.

Boat has four circuits. One dedicated to battery charger and immersion for the calorifier.
A second supplied power to the aft cabin, a third to the saloon and galley. The fourth is unused at the moment.

I have wired up 10 double sockets, two small towel tube heaters, immersion and charger, all connected with armoured cable for safety's sake.

Don't use solid core twin and earth, and if you don't use armour, I'd suggest running cables through conduit.

Try not to run 12 v and 240 right next to each other, just in case a problem in one reacts with the other -- i.e. shorted 12 volt melts through insulation on 240 system (Another reason to favour armoured).

Before plugging in. get someone who knows what they are doing to give it a once over if you have any doubts about your ability!

I have made up the shore power connector in two lengths of "arctic" cable, each a little over a boat length. Usually I can manage with just the one, but sometimes when a longer run is needed I hook them together.

Check voltages to make sure they around 200-240 and it is also worth buying a polarity tester to make sure the marina supply is wired the right way, especially if you visit foreign marinas.

Hope this helps,

All the best,

Nick

 

[Lee_Shaw]

I reckon the easiest way is to get one of them all in one charger things like the Dolphin one. The RCD and MCB’s are already in place fitted to the charger. Neat and easy.

If that is not possible then:

The shorepower inlet is best located in the cockpit or somewhere so you can leave the boat secure whilst charging.

The supply then goes to an RCD which is for your protection in case you start to frazzle.
The individual 240v runs which go to the sockets etc should be protected by circuit breakers (MCB’s). These all fit into a neat box called a consumer unit. I’m not sure about siting this in an cockpit locker. It is not a good idea to get it wet and damage to the unit is also undesirable.

The charger is hooked up and you can charge your batteries from it, as was said above the BEP VSR square cluster is a really good option.

Not earthing your 230v is just sheer laziness and I’m amazed that this would not be done.
Ever heard the expression “to lose the ship for a ha’peth of tar” how about “to lose your life for a few quids worth of cabling and an isolator”.

The addition of a galvanic isolator is widely considered necessary and these aren’t expensive in any case. They are sited “in line” on the earth cable immediately after the inlet plug and it is also hooked up to the boats negative bus.

 

[Guest]

There will be two schools on this ...

Practical DIY and relatively inexpensive.

Cheque book solution where all must be fitted - regardless of cost ....

Lets look at simple and works for majority of people ... Caravan shop will supply a) ready made shore-power cable 10m, 15m or more ... you can buy the individual bits from them as well if necessary, b) suitable exterior socket to fit in cockpit to fit cable to ... no need to hide socket away in locker.
Now off to local DIY establishment and secure yourself a consumer unit and RCB's to fit .... word of advise .... the main power to it should pass through a double pole switch - which switches off both +ve and -ve lines ....
Suggest you now split boat electrics up on the RCB's .... sockets on one, lights to another, charger another .... if you have 4 position unit - you now have spare for 'other'.
Keep everything separate from 12V system and also use double insulated ... then isloator is debateable item. (I don't use one and no problem - in fact I don't connect earth to boat earth .... silly me some would say ??)
Many will say don't use solid core cable .... I have on all boats I've had - and never had problem .... only when intricate and necessary have I used stranded.
Charging .... the 1-2-1-Off has been around for years and survives all criticism etc. It works and no reason to replace unless you want 'smart technology'. If you fit split diode charging - you'll likely find you do not charge ... as voltage drop is too large across it. I know anumber of boats that have had 'smart boost charge' systems - they have removed them after having batterys cook, gas-off, survive less than half normal life ....

Cheque book style : Go to Marine supplier and ask what is needed - buy all he says and spend !!!! Sorry to Marine suppliers - but money's money and its hard earned.

Safety on board is important so make sure RCB's are fitted as soon as possible in the line once cable on board. Support all run cables, no hinges / doors etc. catching them ... above all else - common sense and thought.
/forums/images/graemlins/wink.gif

 

[fireball]

[ QUOTE ]
Not earthing your 230v is just sheer laziness and I’m amazed that this would not be done.
Ever heard the expression “to lose the ship for a ha’peth of tar” how about “to lose your life for a few quids worth of cabling and an isolator”.

[/ QUOTE ]

The earth of the shore power is back up to the marina supply - otherwise your RCD would not set.
If you use double insulated 240v equipment and it does not come into contact with your boat supply then I believe there is no need for a galvanic isolator or extra anode.

If you put a battery charger in place and it is always connected to the battery negative then you are more likely to need these - to protect against stray current between your bits of metal in the water and the marina earth...

The extent of your purchase for "shore power" depends on what you really want to do and how often - if your on a swinging mooring and only get shore power when you go to a marina berth then your more likely to be reasonably self sufficient and only require the minimum of equipment - an RCD even if it is just the plug in one is always recommended though.

 

[AIDY]

These are great bits of kit if you are installing 240v to your boat. All you need in one box. battery charger for up to 3 batteries, ring main, just need to buy wire for a ring main, sockects and wire for connecting to batteries.

I installed one from index marine a couple of years ago same as the plastimo but made by a company called Hi-tec integral, same unit different box. cost about 250 for the full kit to do the installation.

The only problem was routing the ring main round the boat.

 

[Lee_Shaw]

Perfectly true, Afrogley.

I was responding to Williams comment :-

"If there is no connection between either line neautral or earth wires of the incoming power lead to the output wires + and - from the charger and provided the only appliances you use are double insulated (plastic) then you don't need any connection of the mains earth to the ships earth or negative wiring and so don't need a galvanic isolator."

Which I interpretted as advice to not earth up the boats 230v outlets.

I misunderstood the original post, as I thought it said that a permanent charger was to be fitted. If it is I think a galvanic isolator is a wise investment - as they're about £60 - £70, a new prop is way more than that.

 

[TwinRudders]

OK well thanks guys for all the advice.

I'm a still a bit hazy about this business of connecting the mains earth to the ship's earth....why?!

My boat is on a pontoon so may be on shore power for extended periods. Can anyone put into layman's terms the whys and wherefores of a galvanic isolator.

Just to recap...:

I'm going to run the shore power into the cockpit locker. Into an RCB - then from there it goes to two sockets and to power up the battery charger (permanent)

Thanks

J