Wiring diagram

[Summersaltsi]

Hi guys,

 

I'm having a widebeam sail away built. An electrician friend of mine is gonna give me a hand with the wiring, but he is a domestic electrician and was wondering if anybody has an example of a wiring diagram that he can familiarise himself with and get an idea of things. Also any info on current and cable sizes for different services would be amazing.

 

Thanks

Si

[Chalky]

Wiring a boat is different from wiring a house - it's more like wiring a car. Broadly speaking (I know there are other parameters, I'm a Chartered Electrical Engineer) in a house cable sizes are based on the current the load draws, on a boat they tend to be based on volt drop since this usually has a bigger effect on cable sizing than the current drawn. Boat wiring uses stranded cables not solid conductors (to prevent vibration damage) however like a house it has a return wire. There are a number of books on the subject such as "The 12-Volt Bible for Boats" which could help. Also remember this is DC not AC and this can have an effect on the contact materials used in switches and breakers. The Boat Safety Scheme lays out some very basic requirements in this area as well.

[matty40s]

Have a good read of Tony Brooks website and Gibbo's Smartgauge website- or rather, get your electrician to. Lots of good starter information on there, and the above book is also very useful.

[Summersaltsi]

Thanks chalky, I already live aboard and have a good idea about this, I was just wondering if there were any diagrams out there. Ill check out the 12v bible for boats.thanks.

[BargeeSpud]

Have a good read of Tony Brooks website and Gibbo's Smartgauge website- or rather, get your electrician to. Lots of good starter information on there, and the above book is also very useful.

 

Dang! Exactly what I was going to suggest matty, but you beat me to it you tinker.

 

A note to Summersaltsi, you might find the Narrowboat Builder's Book will be a better source of wiring diagrams for narrowboats than the 12V Bible, that's aimed at marine installations in general .

Edited May 17, 2013 by Spuds

[smileypete]

For sizing cable for the 12V stuff, it depends on both the max allowable cable loadings and the max allowable voltage drop between batts and equipment.

 

As far as max cable loadings for 12V stuff go, around the engine room as a rough guide I'd allow a max loading of 3A per mm² for cables 6mm² and over, and max 5A per mm² for cables under 6mm².

 

But bear in mind the BSS does require certain battery, alternator and starter circuits to be at least 25mm², though they still have to be sized properly.

 

Then elsewhere in the boat as a rough guide I'd allow allow max 4A per mm² for cables 6mm² and over, and 7A per mm² for cables under 6mm² (so about 30% higher than the max loadings for the engine room).

 

This will do for most things except extreme cases like running bundles of wires directly over a hot engine, or running wires buried in insulation, but for most things the above should be sufficient.

 

If the cable bill is getting high then in certain cases a higher max rating could be used, but it all depends on circumstances like the max ambient temp, whether the cable is in bundles or conduit, whether there is insulation on one side of the cable, the cable's sheathing material and so on.

 

As far as the max allowable voltage drop goes, inverter and charging circuits can be quite sensitive, I'd allow up to 0.5V at full load for inverter circuits, around 0.2V at max charging output for charging circuits. But having found the cable size to meet these limits it wouldn't hurt to go the next size up if it isn't too dear.

 

But when installing big inverters and chargers, the instructions may call to different minimum cable sizes to the above, so best allow them to take precedence.

 

Other stuff like lights pumps it can be a case of suck it and see, LED lights might no be so fussy, on halogens it can be noticeable, with pumps it depends whether a small drop in performance is tolerable.

 

Also all cables should be protected by the appropriate size fuse or breaker of course. On alternator and starter circuits the batt isolator itself may be considered sufficient but it's still a good idea to fit a big fuse as well, but one that's sized well above the normal alternator or starting current so it's extremely unlikely to blow accidentally.

 

ETA The mains side of things should be quite straightforward for a good spark, some of the differences to house wiring include:

 

Use of stranded cable instead of twin and earth, and why to use ferrules on the stranded cable ends.

Fitting a galvanic isolator, possibly with status monitor, for shoreline installations.

Why a ring main isn't likely to be essential on a boat.

 

cheers, Pete.

~smpt~

Edited May 18, 2013 by smileypete

[Chris Pink]

I've never seen a reference to it in any of the "12V bible" type books but my preference these days is to run heavy duty 12V busses in 10mm² or 16mm² down the length of the boat (with suitable midi or mega fuse) and then run fused spurs to lights and equipment. at 10 foot intervals down the boat. These spurs can be made from 3 or more 6mm machine screws through a piece of 12mm oak with 6mm lug crimps for the buss in and out and 6mm uninsulated crimps to blade fuses for the spurs. Use heat shrink to protect the terminations.

 

Saves a fortune on copper and makes fault finding a doddle and saves a big headache on labelling.

 

Tri-rated cable is the stuff to buy, but it in 100m reels from a electrical wholesaler and try and economise on the number of sizes. I think apart for running the large stuff which, inevitably, you have to buy by the metre you can do a boat in 100m each red and black 6, 2.5 and 1mm². It costs a fortune to buy bitty lengths of cable.

 

Don't use those awful crimp connectors with red, blue and yellow ends they are horribly, difficult to get a really good crimp and don't support the cable properly. Use good quality uninsulated crimp terminals with a good heat shrink. The exception, unfortunately seems to be butt crimps which are difficult to find in small uninsulated sizes. Another aid to consider is Helacon connectors, cheap as chips and which make the one to many type connections a doddle.

[Ally]

If you pm me an email address I'll try & sort time to send you a couple of sample schematics next week, if you still want some by then.

[tree]

If you pm me an email address I'll try & sort time to send you a couple of sample schematics next week, if you still want some by then.

Ally, my lovliness xx could you also send me a sample of a schematics thingybob ? pretty please.

I have got the following books : Narrowboat Bukiders Book, 12 volt bible for boats and Narrowboats Care and Maintenance. But owt else will help moi.

The treepoet addy will find its way to me

oddles of treescrunching huggles xxxxx

sowwry Summersaltsi for highjacking your thread ...hope you dont mind it is only a lickle bit of highjacking, Thanks

[Summersaltsi]

Thanks for all the advice , all very complicated but I'm sure it will sort itself out once I start

[Ally]

Tree...I only have your facebook email addy...will you get that? If not, please pm me your email addy, also somersaltsi, if you want the schematics, I need your email address. (by private message)

Edited May 20, 2013 by Ally

[Ally]

Tree...found an email for you and have sent the schematics on to you as attachments.

Somersaltsi....I tried to message you but you haven't made enough posts yet to use the message system. Sorry, can't help without an email address, as I cannot publicly share the schematics.

[smileypete]

Thanks for all the advice , all very complicated but I'm sure it will sort itself out once I start

 

OK too much information maybe

 

Here's a very rough guide to what range cable sizes are used for different items:

 

25mm-70mm Battery, alternator, starter circuits, inverters up to 2kW

10mm-16mm Inverters up to 500W, solar up to 400W-500W, feed to fuse panel for smaller loads

2.5mm-6mm Solar up to 150W-200W, moderate length feeds from fuse panels to lights, pumps, etc.

1mm Short feeds to LED lights, single halogen lights, small bilge pumps

 

If there was a sketch of the rough physical layout of things with details of the items to power and the distance from the batts that would help to narrow it down.

 

The best size cable to use depends on the what sort of item is being powered, how much current or power it draws, and how far it is from the batts.

 

If you get your sparky friend to read the whole thread that should be a help to him.

 

cheers, Pete.

~smpt~

Edited May 20, 2013 by smileypete

[system 4-50]

This is not what you need but it is very pretty.

[ditchcrawler]

This is not what you need but it is very pretty.

There are no lights

[system 4-50]

There are no lights

Which is why he doesn't need it!

And it is still very pretty!

[ditchcrawler]

Which is why he doesn't need it!

And it is still very pretty!

Don't tell me you have it framed and hanging on the wall

[Ally]

Summersaltsi, I have now emailed them to you...hope they are useful. You may find it in your spam box, so please check that...from my work email, which as you don't have me as a contact, will sometimes go to spam!! (Beacon Boats)

[smileypete]

Don't use those awful crimp connectors with red, blue and yellow ends they are horribly, difficult to get a really good crimp and don't support the cable properly. Use good quality uninsulated crimp terminals with a good heat shrink. The exception, unfortunately seems to be butt crimps which are difficult to find in small uninsulated sizes.

 

Despite the risk of disagreeing with the esteemed Mr Pink I have to differ! Each to their own, but using decent terminals and a good ratchet crimper makes all the difference.

 

The better push on terminals have an extra anti-vibration insert/sleeve/ring under the insulation. The sleeve helps support the wires insulation and also makes for a tighter crimp. In the pic below, the right hand ones have the sleeve, the bottom left don't:

 

 

Of course, preaching to the choir, but a decent ratchet crimper should be used and not NOT the cheapo plier type which doesn't work nearly as well.

 

Finally if the connection is in a damp place or might get exposed to water sometime, it's a good idea to use wire with tinned copper strands, or at least dip the bare end in Vaseline or some comparable goo before crimping.

 

Another aid to consider is Helacon connectors, cheap as chips and which make the one to many type connections a doddle.

 

Maybe but it appears they're not intended for fine stranded wire:

 

http://www.hellermanntyton.co.uk/site/products/helacon-plus/hecp-3/148-90001

 

It looks like the Wago ones are but I'd still be wary of using them somewhere which can get quite damp:

 

http://www.wago.com/cps/rde/xchg/SID-F68A570A-ECBF6FEA/wago/style.xsl/eng-2631.htm

 

cheers, Pete.

~smpt~

Edited May 22, 2013 by smileypete

[Summersaltsi]

Thanks for all your help much appreciated .

 

Chris why use tri rated cable, is that bss? What's the difference with that and normal multistranded?

[Chris Pink]

If you ask for tri-rated or control wire in an electrical wholesaler you'll get what expensive suppliers supply (more cheaply)

 

What's 'normal' multi-stranded?

[by'eck]

This is not what you need but it is very pretty.

 

Oi that's mine, but an early version

 

Updated version

 

 

Probably way OTT and only includes the main parts of DC distribution to control panel.