hi there,new member in need of electrical advice

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firemansam

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hi there new to this forum have looked for some advice on here with regards to a question but have not found any answers,so here goes,my question is this,is it possible to take a complete electical system out of a caravan and use it on a boat, at the moment i have a westerly tempest with no shore power connections,i am thinking of installing shore power supply,ie a battery charger and 3/4 240v three pin sockets around my boat,so that when i plug shore power in my batteries get recharged and i can use a tv and kettle etc,i also have a caravan and in a moment of contemplation,i realised that i had an exact system installed in my caravan,ie when i plugged it in on site it did all the things that i mentioned before,so could i therefore use that system from a donor caravan,albiet with a little tweeking.


regards in advance:confused:
 
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Broadly similar

I am sure you will be familiar with the standards and the section of the !EE wiring regulations which apply to mains power installations in caravans

The international standard which applies to small boats is ISO 13297 (2012). Borrowing or stealing a copy of this would be a good starting point.

I am not familiar with the detail of the wiring requirements in caravans but one thing that immediately comes to mind that is an advisable part of a shorepower installation in a boat but which is not applicable to caravans is a "galvanic isolator" (qv).
 
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Viv is right in that the earthing of the system becomes much more critical because on a boat you are much more likely to be in contact with metal with a good connection to earth (the sea). Hence it is advisable to connect the system earth to the boats earthed components like the engine and prop. This is where it becomes tricky because the earth connection can cause all sorts of problems to your boats metal (galvanic corrosion) other boats and even the jetty hardware. (our club insists ona GI for any boat with permanent connection to mains) This happens when you have power connected 24/7 not such a problem for short term ( few hours) connection. (removed power lead completely not just switched off) The galvanic isolator can provide a connection for safety but is not a connection for low voltages less than 1.4 volts so provides blockage protection from the small current/voltages of galvanic corrosion. good luck (be careful) olewil
VicS said:
Broadly similar

I am sure you will be familiar with the standards and the section of the !EE wiring regulations which apply to mains power installations in caravans

The international standard which applies to small boats is ISO 13297 (2012). Borrowing or stealing a copy of this would be a good starting point.

I am not familiar with the detail of the wiring requirements in caravans but one thing that immediately comes to mind that is an advisable part of a shorepower installation in a boat but which is not applicable to caravans is a "galvanic isolator" (qv).
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In simple terms yes, you could lift and drop the system in your caravan into your boat and it would work more or less but there are a few complications. The first is that you are surrounded by salt water, which is a great conductor. Another is that your boat probably has two batteries, one for the engine start and one "house" battery for the domestic side, nav lights, etc. There are problems from the salt water water not just because it conducts so can create a nice circuit from the mains supply to earth via your body but because it also encourages galvanic corrosion, where one metal part of your boat, such as your propeller, can decide to migate part of itself to another metal surface - as per VicS comments.

I'll disagree with with Mr Mercier and say "if you're not bright enough to ask, you shouldn't be doing things with electricity". Try Nigel Calder's "Boat Owner's Electrical and Mechanical Manual" (don't buy it from the RYA unless you want to pay twice the Amazon price) or even just Google "Yacht Electrical Systems" or similar. There's a load of pre-written stuff on the web and the good and accurate advice outweighs the bad by a large margin as far as I can see.

Once you've had a look try drawing up your own circuit diagram and put it on here for some gentle and constructive criticism :rolleyes:
 
In simple terms yes, you could lift and drop the system in your caravan into your boat and it would work more or less but there are a few complications. The first is that you are surrounded by salt water, which is a great conductor. Another is that your boat probably has two batteries, one for the engine start and one "house" battery for the domestic side, nav lights, etc. There are problems from the salt water water not just because it conducts so can create a nice circuit from the mains supply to earth via your body but because it also encourages galvanic corrosion, where one metal part of your boat, such as your propeller, can decide to migate part of itself to another metal surface - as per VicS comments.

I'll disagree with with Mr Mercier and say "if you're not bright enough to ask, you shouldn't be doing things with electricity". Try Nigel Calder's "Boat Owner's Electrical and Mechanical Manual" (don't buy it from the RYA unless you want to pay twice the Amazon price) or even just Google "Yacht Electrical Systems" or similar. There's a load of pre-written stuff on the web and the good and accurate advice outweighs the bad by a large margin as far as I can see.

Once you've had a look try drawing up your own circuit diagram and put it on here for some gentle and constructive criticism :rolleyes:
 
I am afraid i have to agree with Nigel
If you have to ask, you shouldn't be doing things with electricity.[/unquote]. Don't play with the leccy until you do some reading on the subject. Your apparent present level of knowledge is insufficient to permit you to safely play with the wee 'lectrons.
As our resident Grumpy old git says there are plenty of boat electrical books available - many free to download.
Basically the wiring is simple (use tinned flex), leave some slack at each outlet for future cut back when changing outlets (they will corrode very quickly) do look at fitting a galvanic isolator as per Vic's advice. When you think you have it all worked out by all means post your wiring diagrams here along with types of outlet etc . Another thing to consider is using conduit or trunking for your cables - makes it so much easier to change later if needed and if cables cannot be secured / hidden trunking can make a reasonably neat job. Remember the 240v wiring must be protected from accidental damage.

Nearly forgot - you might consider a combi charger/inverter rather than a straight charger (though both have pros and cons) if you have the battery bank to run one - handy to have 230v onboard for microwave, Vacuum cleaner, Memsahib's hairdrier etc.

Above all do not panic - it is not rocket science but there are a few things you must be aware off for the safety of the boat and crew.

Finally do not be afraid to post and ask questions - everyone had to learn at some time (though some think they were born with the knowledge) and htere is a wealth of information and assistance free for the asking.
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grumpy_o_g said:
In simple terms yes, you could lift and drop the system in your caravan into your boat and it would work more or less but there are a few complications. The first is that you are surrounded by salt water, which is a great conductor. Another is that your boat probably has two batteries, one for the engine start and one "house" battery for the domestic side, nav lights, etc. ...
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I expect the OP is thinking of a towed caravan, but many or most motorcaravans have a dual-battery system, just like a boat's.
 
My shorepower system includes a marine (Sterling) charger and a galvanic isolator. All other components (RCDs etc.) came from a caravan "chandlery". The boat has been professionally surveyed three times since I installed it, and it has been given the OK by all surveyors. Despite the galvanic isolator and a correctly connected zinc anode, I have galvanic problems with the prop.
 
grumpy_o_g said:
I'll disagree with with Mr Mercier and say "if you're not bright enough to ask, you shouldn't be doing things with electricity". Try Nigel Calder's "Boat Owner's Electrical and Mechanical Manual" (don't buy it from the RYA unless you want to pay twice the Amazon price) ...
Click to expand...
Sure, the only stupid question is the one you don't ask. However, electricity can be dangerous, so some guidance is required, and more than can be given here. Agree about the book: http://amzn.to/1g7B7gH, I have a background in electronics and I've rewired my entire house, but even so I needed to read up on boat wiring.
 
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Rewired our house (the wiring when we moved in dated to the very first days of domestic electricty - early C20th) and have rewired the 12v system on two boats but would get a 240v boat system installed professionally by a marine electrician (at least as far as the distribution panel - you could then wire the sockets in).
 
VicS said:
welcome-1.gif
welcome-1.gif

Broadly similar

I am sure you will be familiar with the standards and the section of the !EE wiring regulations which apply to mains power installations in caravans

The international standard which applies to small boats is ISO 13297 (2012). Borrowing or stealing a copy of this would be a good starting point.

I am not familiar with the detail of the wiring requirements in caravans but one thing that immediately comes to mind that is an advisable part of a shorepower installation in a boat but which is not applicable to caravans is a "galvanic isolator" (qv).
Click to expand...
After reading a previuos thread on electrics, I concluded that a galvanic isolator was rarely necessary.
 
ghostlymoron said:
After reading a previuos thread on electrics, I concluded that a galvanic isolator was rarely necessary.
Click to expand...

If the shore power system has it's earth bonded to the DC negative and/or the anodes etc, as it should be, and the shorepower is left plugged in for prolonged periods then fitting a galvanic isolator would be advisable and likely to be necessary.

Obvious exceptions would be if there are no anodes or other vulnerable underwater fittings; if the installation has been done to an old standard which does not always require the earth bonding or to no standard; and if the shorepower is not left plugged in for lengthy periods.
 
thank you all so much for your quick replies,i will be reading up on the subject over the winter and producing a wiring diagram to put on here,i realize it would need a bit of tweeking,ie a galvanic isolator etc,but the basic idea seems sound,i do have 2 batteries so would need to connect both for recharging,and i would be running the cables through conduit,i am going to the boat show next month and will ask advice and prices for a dedicated marine system whilst there,and if this is horrendously expensive then i may have no alternative but to go down the caravan donor route.
 
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