Cheap Shorepower option?

[ontheplane]

Having a look at these :- http://www.outdoorworlddirect.co.uk/acatalog/sunnflair_hookup.html

Now whilst it would undoubtably work, would be messy with extension cables all over the place.

So I was looking at it thinking, what fundamentally do I NEED to have shorepower.

So here are my thoughts.....

1) Lead to Boat - these are easily obtained.
2) Connector on the boat to wiring distributed around the boat.
3) Some sockets dotted around the boat.

Now the questions:-

a) If I am only plugging things in TO the sockets rather than having anything attached to the boat will this have any effect on galvanic corosion (I will only be plugging in in marinas occasionally not leaving it connected when I am away).
b) If I plug in a battery charger(s) to sockets in the engine bay will I then need a galvanic isolator
c) Is it better to have the RCD's nearer the end of the circuit or the start? So I have 2 options - fit a consumer unit right next to the inlet - then out to regular sockets OR straight wiring to the sockets and then RCD's in each socket (will buy the sockets that have RCD's built in) OR do I need both i.e. consumer unit then wiring out to RCD'd sockets. Will this last option interfere with each other and perhaps neither would trip if there is a problem.

I would like to wire this up myself and then (if required) get a sparkie to check it over - although my Dad is very good with electrics (has rewired houses to high standard before but doesn't have the latest certification) will I be breaking the law if I don't get an electrician to check all this over - or worse do I have to get them to install it all at outrageous cost?

 

[VicS]

An extension lead and multi-socket outlet is one thing and perhaps just about adequate for very occasional use.

If you are going for an installation of fixed sockets around the boat then you should bring the power in to a consumer unit that includes an RCD and circuit breakers. For a basic installation a "garage consumer unit" may be adequate. Once you have a fixed installation the earth should be connected to the vessels earth system. That then introduces the possible need for a galvanic isolator in the incoming shore-power earth connection. Not strictly necessary if you will not be leaving the shore-power lead plugged in but it could be vital if you do.

A battery charger plugged in to an extension lead should have a fully isolated output and so that in itself will not create the need for a galvanic isolator.

An RCD should be incorporated into the consumer unit and therefore individual RCDs at the sockets should not be necessary but they will not interfere with each others operation if you do use them. There should be an RCD in the marina's pontoon supply anyway.

If you regard battery charging an important function look out for boat consumer units and battery chargers combined. There are some which, although expensive, make a very neat method of fitting a battery charger. Unfortunately I cannot remember the name of them but I am sure you will find them on the usual websites for boat electrical equipment. I'll come back again if I remember what they are.

A check by a competent electrician would be advisable but to the best of my knowledge you will not be breaking any laws by doing the installation yourself (unlike house wiring now) BUT check if you are talking about use on the inland waterways.

Rather a pity you did not post the question on Reader to Reader as I think you would have got a lot of sound advice there

 

[VicS]

These HERE are the combined distribution units and battery chargers I had in mind. Expensive as I already said but a very neat solution for a boat that does not already have a shore power installation

 

[cliff]

Cheap shore power? After following Vic's advice, plug into the boat along side you, not th epontoon outlet - cheapest power available /forums/images/graemlins/grin.gif

Just make sure the owner is not around nor liable to be around. /forums/images/graemlins/wink.gif
---------------------

Artificial Intelligence is no match for Natural Stupidity

 

[gjgm]

I think the prefered RCD is double pole(if thats the right wording), so it breaks both wires. When I looked at this before, while you can do a cheapo "garage job", it rapidly became not cheap when you spec'd it up to a marine installation. My numbers might not be correct as it was a while ago, but on initial research, I thought maybe £50, but the time I went the whole hog with chargers etc it zoomed to many £00's. Maybe it was mentioned on another reply, but there was a nifty unit that had rcd and chargers in one, that seemed a convenient, if not especially cheap, way to go.. pretty much plug and play. I m sure someone will know the unit, or you'll find it on the net somewhere. £2-300, I think.
However, years ago, I managed to get by fine with one of those camping ones for occasional use, for some tea and toast etc ! Depends just how "installed" you really need, or want to spend /forums/images/graemlins/wink.gif

 

[ontheplane]

Yikes!! Looks a good unit but nearly £400 notes!

I am thinking the Caravan type might be the way forward here!!

BUT - if the caravan type is safe (and not connected to the boats earthing system, why would I need to connect a fixed one to the boats earthing system as long as I used the same kind of system (i.e. RCD's at all outlets)?

 

[ontheplane]

I have looked at these Consumer units, and they all seem to fundamentally do the same thing - I.e. distribute out the power put in via circuit breakers - is that right?

So I am looking at the following in terms of costs I am thinking...

1) A garage consumer unit - £12.00 + say 3 breakers around £4 each
2) 3 Outlet plugs with RCD's (prob not strictly necessary with the consumer unit but better safe than sorry in my book) - about £4.00 each
3) Wiring
4) Inlet for power - from £3-4 for a surface mount to £10 for a flush fit one (don't know if I have anywhere I can fit one of these)
5) Cable £20 ish
6) 2 x Chargers £40 each or so.

My belief is, that the more advance chargers can be permanently wired up to the battery as they will only allow power in one direction, is that right?

So all in all around £150 ?????

Am I being overoptimistic or is it relatively simple....?

 

[VicS]

The garage consumer units I have looked at contain a 30mA RCD (to the best of my knowledge a 2pole device, ie switches live and neutral) and two mcbs, one of 6A rating intended for the garage lights, and one of 16A intended for the power circuit and are weather proof to IP55.

If not required for lights on the boat the 6A circuit could be used for a fixed battery charger.

I am looking at prices around £25.

Socket outlets with inbuilt RCDs do not offer any increase in protection and there is no guarantee that the local RCD will trip in preference to the central one.

The obvious downside of the central RCD is that a fault on one circuit will trip everything which is why in domestic installations a separate circuit can be provided for fridges and freezers.

Any battery charger can be left connected to the battery. the rectifier in it will prevent current flow in the reverse direction.. Modern advanced battery chargers can be left connected AND switched on because they automatically sense when the battery is charged and switch to a low output maintenance charge regime. I think £40 or so will get you a portable automatic charger. Last time I looked Halfords had something quite sophisticated for that sort of price or only a little more.

Spending a bit more will of course get you an automatic charger with two or more independently controlled outputs that can be installed permanently.

It is the current recommendation that the earth of a shorepower system should be connected to the ship's earth system. Some people do not agree with it but that's the situation. It is all but impractical to do it with a temporary extension lead arrangement.

 

[ontheplane]

Thanks Vic sounds like you really know what's what.

I am lucky in that I have a trade account with a local supplier Stax - so yes the Garage units that are around £30-£40 I can get for £12 - 15+VAT, the RCD modules £3 or £4 instead of £6 or so... hence the prices quoted.

Assuming therefore that I do want to fix the earth to the boat's earth - would I just run a cable to the engine block, or the battery negative terminals?

I can get chargers from there as well at around 50% the cost of the ones in Halfords - same things.....

Thanks for all your help.

 

[VicS]

Make the earth point the connection at the engine block rather than the battery terminal

I am waiting for some other input to this thread. Perhaps when they have all been back at their office desks for half an hour on Monday. They musy all be lifting out and scrubbing bottoms this weekend. (glad I did mine before the weather started getting colder)

 

[Sneds]

I think you are refering to an MCB as an RCD?
They are different, an MCB acts like a fuse and will trip when overloaded and an RCD will trip when you have leakage to earth.
Of course, the leakage to earth may well cause an overload.
Your consumer unit will need mcbs to feed each circuit, ie one for lights and one for power the rcd is the incomer and protects every thing.
Good luck and feel free toa ask some more /forums/images/graemlins/smile.gif

 

[ontheplane]

Yep you're right - there is the RCD in the box then up to 8 things which "clip" in - they are as you say the things that trip when the load gets too high.

I am beginning to think that as long as I get my Dad to help (he's pretty good with electrics) then this is a job I can tackle very cheaply and relatively easily. I do think I will need his help in making sure I don't miss anything and blow myself up!!

Thanks all for your input.