Wiring a sailaway

[jddevel]

Advice please.  With my sailaway and  having been let down by a couple of Marine electricians locally (near Plymouth,Cornwall) and now getting to the stage where it`s case of DIY as much as possible. Please advise what and where I should start reading or as 12 volts is totally new to me do I hope third time lucky. I would add that the company LoomTec provided the original basic loom -some of which apparently due to cable sizing is to require smaller and more expensive MCBs but due to other design changes (the use of 240v fridge instead of 12 volt and macerator toilet instead of vacuflush) some cabling has to be modified.

[Tony Brooks]

Start by studying the electrical notes on my website. I have tried to write them so non-technical people can understand. Then either email (not PM) any questions to me or ask n the forum.

There are other topics like this and you will find some books/downloads recommended.

Perhaps the most important thing to grasp is how to calculate cable size (conductor cross sectional area) for the current it has to carry AND the total out and back run length. After that its much like a domestic radial circuit.

[ditchcrawler]

Note that you must not use any cable in the 12 volt loom for a 240 volt feed to your fridge or any other outlet.

[Tony Brooks]

Yup - 50mm separation or one in conduit I think.

[Alan de Enfield]

25 minutes ago, ditchcrawler said:

Note that you must not use any cable in the 12 volt loom for a 240 volt feed to your fridge or any other outlet.

I think that is one of the reasons the OP was advised not to use a 'pre-formed' wiring loom.

Unfortunately he did.

[Sea Dog]

3 minutes ago, Alan de Enfield said:

I think that is one of the reasons the OP was advised not to use a 'pre-formed' wiring loom.

Unfortunately he did.

Oh dear - I was just thinking how I recall someone who spent ages justifying his idea of using a wiring loom company last year despite everyone explaining why he shouldn't. Have the chickens come home to roost?

[Chewbacka]

53 minutes ago, Sea Dog said:

Oh dear - I was just thinking how I recall someone who spent ages justifying his idea of using a wiring loom company last year despite everyone explaining why he shouldn't. Have the chickens come home to roost?

A gentleman never says 'told you so' he just quietly and smugly smiles to himself.........

[Sea Dog]

2 minutes ago, Chewbacka said:

A gentleman never says 'told you so' he just quietly and smugly smiles to himself.........

Gentlemen, start your engines!  Do you have a problem, Sir...?

[reg]

Firstly I would take up Tony Brook's advice to look at his website here

http://www.tb-training.co.uk/cover.html

I used it when I wired my sail away a few years ago. A wonderful resource and freely given. 

Belated thanks and greenies Tony, resource much appreciated. 

 

Secondly Whilst a full 12v wiring loom may look complicated in essence, and at its very simplest, all you have to remember is that you are taking a red wire out and a black wire back. I found that remembering this simple fact made wiring a lot easier. 

 

 

Edited May 11, 2017 by reg
Correction

[jddevel]

Thank you all for your comments and advice. Couple of responses. Regarding LoomTec I requested their assistance in the first place for two reasons 1) Speed I could get on with other things with which I was more familiar 2) They offer a service which provides the necessary documentation to comply with RCD certification.

My problem however arose when as I`d requested this loom when the boat was at Swanley Bridge Marina as a basic sailaway (engine etc. windows ,ballast and flooring) and the interior was still at the very early interior design, changes following trawling through the Forum and thinking through things in a great more detail have resulted in washing machine, 240 volt fridge-freezer etc etc (traditionalists please don`t throw your hands up too high please) solar power sourcing, ideal batteries (for the novice) how to connect them all efficiently. Large inverter and battery charger, I.Transformer, battery management and monitoring system set up. Plus the potential stripping of the existing thin sprayed coat of Interluf 16 and using Zinga The list goes on and on and I`m still no where near the water!!!!!!!

Thank you for the pointer on the 240 volts. Fortunately I was aware of that. HOWEVER having ducted 2.5mm artic blue which I was advised by one electrical engineer (since disappeared abroad) was necessary I was then advised that this from the 3000watt Vitron was not big enough. I must admit this conflicted with my knowledge of domestic 13 amp were a 2.5 ring main carrying -rule of thumb- no more than 13 sockets for example on each ring. As I had one to frigefreezer, gas cooker ignition and one socket plus one to  three sockets and a spur from one to the washing machine isolator I thought this was adequate. Obviously wrong.

I think my basic concern is an apparent conflict with advice. LoomTec apparently having put in what I assume is the basic necessity size wise for power users it has resulted in the need for smaller and therefore more costly rcds/mcbs. Plus I quote "due to your large inverter everything has got to be 500A rated (or above) hence the cabling and blocks and switch are of higher grade" (2nd engineer whose current work load means a lengthy delay before getting to me) Means much of the fitout would have to be put on hold.

I hope from the above you appreciate my mind set when all I want to do is get afloat!!!

Am now considering moving the boat from Cornwall to a working marina where the electrics and engine commissioning can take place. Ideally somewhere between Bristol and Birmingham/M42. Any suggestions? Would like to see the boat in the water before Christmas Ha Ha (this year)

[Tony Brooks]

1. A domestic ring in 2.5 sq mm CCSA is in effect 5 sq mm CCSA because its a ring. It is not clear if your 240V AC wiring is a ring or radial.

2. I question the bit about the cable not being big enough for the inverter. I dread to think what the maximum current you could draw into your house, I bet it would equate to many multiples of  3000  watts. the basic rule is that fuses/circuit breakers at the distribution box are sized to protect the cable. so as long as your mains MCB is rated to whatever 2.5 sq mm CCSA cable can safely carry or less there shoudl be no safety issues or problems. Try to draw more current down the circuit that the MCB rating and it opens, protecting the cable. The run between the inverter and the mains distribution box MUST be rated for the full inverter output though because it has no overload protection save what may or may not be built into the inverter.

3. The comment about 500 amps without being very precise what it is referring to smalls to me like  bovine excreta or an excuse to bump up the price. It may be true for the cables between battery and inverter, the battery interlinks, any inline mega fuse and the battery isolating switch but even then 3Kw only equates to about 300 amps at 12v. It should not be true for any other circuits apart from just possibly the starter's main wiring but that has nothing to do with the inverter.

I hope I am wrong but I fear you have been seen coming and assessed as ripe for plucking. I think I tried to warn you about a certain wiring harness maker's mistakes.

Others far better qualified in 240V AC electrics will, I hope, tell me if I have got anything wrong.

[Chewbacka]

1 hour ago, Tony Brooks said:

1. A domestic ring in 2.5 sq mm CCSA is in effect 5 sq mm CCSA because its a ring. It is not clear if your 240V AC wiring is a ring or radial.  But a domestic ring has a 32A breaker, if the shore supply is max 16A and the inverter is max 13A and 2.5mm2 cable is rated at about 20A (depending upon how well it is ventilated etc, it could be 16A) then 2.5mm2 cable should be ok.  If the inverter has a power boost function, ie it can top up the shore supply to say 5 or 6kW then 2.5mm2 is probably too small, but again it would also depend upon the breaker used for each circuit, see also Tony's comments below.

2. I question the bit about the cable not being big enough for the inverter. I dread to think what the maximum current you could draw into your house, I bet it would equate to many multiples of  3000  watts. the basic rule is that fuses/circuit breakers at the distribution box are sized to protect the cable. so as long as your mains MCB is rated to whatever 2.5 sq mm CCSA cable can safely carry or less there shoudl be no safety issues or problems. Try to draw more current down the circuit that the MCB rating and it opens, protecting the cable. The run between the inverter and the mains distribution box MUST be rated for the full inverter output though because it has no overload protection save what may or may not be built into the inverter.  Agreed.

3. The comment about 500 amps without being very precise what it is referring to smalls to me like  bovine excreta or an excuse to bump up the price. It may be true for the cables between battery and inverter, the battery interlinks, any inline mega fuse and the battery isolating switch but even then 3Kw only equates to about 300 amps at 12v. It should not be true for any other circuits apart from just possibly the starter's main wiring but that has nothing to do with the inverter.  The 500A comments from the electrician is very unclear.  As Tony has said even with inverter losses and a low battery voltage the inverter will not be taking more than about 325A.  If the electrician is basing his calculations  on the inverter having a surge capability of say 5 or 6kW  then it could be 500A, but the surge capability is only for a very short time, so switches etc continuously rated for 500A sounds excessive to me.  It is something to consider.

I hope I am wrong but I fear you have been seen coming and assessed as ripe for plucking. I think I tried to warn you about a certain wiring harness maker's mistakes.  Possibly more a case of when spending someone else's money, then a bit of over spec is tempting, but should last forever........

Others far better qualified in 240V AC electrics will, I hope, tell me if I have got anything wrong.

Some comments in bold above

[jddevel]

I feel that the last two comments are in keeping with my instinct regarding the companies` quote for materials needed. His view regarding work load was only forth coming when I asked for a precise breakdown of his costings as I felt that as forum contributors are well aware "shopping around" can often buy the same product more competitively. Their company response was work load prohibited this- one can only respond by saying how did you arrive at the quote then.

2 hours ago, Tony Brooks said:

I think I tried to warn you about a certain wiring harness maker's mistakes.

Unfortunately after I`d bought their service and started accruing information and knowledge from the forum members.

However after a afternoon considering it  and provided I get a good nights sleep, as I feel the new engine will need commissioning and the wiring issue may more easily be resolved by a working boat yard my leaning is to get the boat moved northwards to the canals and get it dealt with.

 

[smileypete]

Can't Loomtec recommend anyone?

Could try sending a PM to NMEA and Keith M, they're outside your area but might know of someone.

Failing that find the trained installers lists for companies like Mastervolt, Webasto, Victron, some of them might do general wiring.

Though it's good to learn about wiring and stuff, modifying and installing a loom for a new boat may not be the best place to start!

Even an hour or two with a good marine electrical specialist going over the loom design/spec and the required install may get plenty of good info which could otherwise take many hours of learning.

Edited May 11, 2017 by smileypete

[Tony Brooks]

11 hours ago, smileypete said:

Though it's good to learn about wiring and stuff, modifying and installing a loom for a new boat may not be the best place to start!

From what the OP said at the start of this thread I suspect the loom is probably OK,  He needs to ADD 240 volt wiring and sort out what looks like somewhat suspect "advice".

[Alan de Enfield]

21 hours ago, jddevel said:

LoomTec provided the original basic loom -some of which apparently due to cable sizing is to require smaller and more expensive MCBs but due to other design changes (the use of 240v fridge instead of 12 volt and macerator toilet instead of vacuflush) some cabling has to be modified.

 

4 minutes ago, Tony Brooks said:

From what the OP said at the start of this thread I suspect the loom is probably OK,  He needs to ADD 240 volt wiring and sort out what looks like somewhat suspect "advice".

I must admit to reading the OP as suggesting that the cabling IN THE LOOM has to be modified.

 

Hence the information that the 220v (new) cabling for the fridge cannot be run within the loom.

[Tony Brooks]

But it should still be easier to run new cables. 12V tied to the loom and mains separated in some way.

[Rob-M]

13 hours ago, jddevel said:

I feel that the last two comments are in keeping with my instinct regarding the companies` quote for materials needed. His view regarding work load was only forth coming when I asked for a precise breakdown of his costings as I felt that as forum contributors are well aware "shopping around" can often buy the same product more competitively. Their company response was work load prohibited this- one can only respond by saying how did you arrive at the quote then.

Unfortunately after I`d bought their service and started accruing information and knowledge from the forum members.

However after a afternoon considering it  and provided I get a good nights sleep, as I feel the new engine will need commissioning and the wiring issue may more easily be resolved by a working boat yard my leaning is to get the boat moved northwards to the canals and get it dealt with.

 

We had work done whilst our boat was at Saul Junction marina on the Gloucester Sharpness, we used a local electrician, Giles Wilkins, who does lots of work on narrowboats. However, like any good tradesman getting his time was difficult but once he was actually on the boat he completed the work quite quickly and at a good price. If you decide to move your boat around the Gloucester area PM me if you would like his contact details.

 

 

[jddevel]

Only addition to be made to the loom is the cable to the macerator toilet as the cable to the original toilet I was going to use was a Dometic Vacflush (if memory serves me 7.5amps were as Vetus is 25amp) so have laid in an additional duct with a "pull through" to accommodate the change. Due to this and other changes 12v frig to 240vfrig etc will have a number of currently (excuse pun) "tails" which I will cap off for possible later use. I have also laid in 2.5 artic blue in duct to the service points for the various 240 volt products. My main issues are the installation of inverter, battery charger, buzz bars and sizing the two fused consumer units (240 and 12volt) and more importantly without spending to much more time on learning get it done. My time at the moment is making up oak porthole frames, ordinary oak frames bespoke furniture etc etc. I`d just like this particular work put in the hands of the professionals. 

[jddevel]

Thanks Rob-M Spent yesterday p.m. looking for a suitable location around 4 hours from our home (near Plymouth). As a large corporate type marina is not to our personal liking but rather the smaller mooring/boatyard/marina including a CRT mooring (with some local facilities) we are looking from Bristol to around Birmingham. Around Brum gives us some excellent cruising opportunities so it currently heads the list. Maybe Gailey wharf area for example. But any advice or pointers welcome from all obviously. It`s a long way to travel just to instantly reject something. We had that when we spend hours and days of fruitless search before deciding on a sailaway. I`d even bought a trailer cruiser -out of frustration -which never went near the water after I realized it just wasn`t fit for purpose. Hope this doesn`t seem as if I`m too fussy - we just don`t want to have too many regrets and spoil the dream.

[Chewbacka]

47 minutes ago, jddevel said:

Thanks Rob-M Spent yesterday p.m. looking for a suitable location around 4 hours from our home (near Plymouth). As a large corporate type marina is not to our personal liking but rather the smaller mooring/boatyard/marina including a CRT mooring (with some local facilities) we are looking from Bristol to around Birmingham. Around Brum gives us some excellent cruising opportunities so it currently heads the list. Maybe Gailey wharf area for example. But any advice or pointers welcome from all obviously. It`s a long way to travel just to instantly reject something. We had that when we spend hours and days of fruitless search before deciding on a sailaway. I`d even bought a trailer cruiser -out of frustration -which never went near the water after I realized it just wasn`t fit for purpose. Hope this doesn`t seem as if I`m too fussy - we just don`t want to have too many regrets and spoil the dream.

So long as your dream is realistic.  I've known people spending ages looking for the perfect house and never finding it and getting more fed up over it.  Reason being their dream house is worth £500k but their limit was £350k................

[jddevel]

Understand your comments Chewbacka. Unfortunately our difficulty is/was budget in relation to the fact that with second hand craft we discovered that many were either to our mind grossly over valued or whilst great boats we did not want to compromise to much on what we had planned on. We looked at the new market but there the stumbling block was a good boat builder has a order book anything up to two years at least in advance. We are both in our seventies and were not sure we wanted to wait that long. Plus with over 50 years of canal holidays and over 40 years in the bespoke property development market with a multitude of trade skills at hand- well we like to think so-we saw nothing that we couldn't with the right advice get to grips with. However realistically 12 volt electrics is our stumbling block and its relationship with steel canal craft. As you are aware it`s not like wiring up a house. The comparison I would make is it`s like the plumber getting another plumber in to fix a leaking tap but might get a tradesman in to install a bore hole and private water supply. Different skill set and knowledge required. Hope you understand.

[Neil Smith]

You are right to sticking to what you know imho, that's how I did it by getting an electrician that spends a lot of his time wiring up barges on the thames.

Also you don't need to duct your artic blue as the outside insulation acts as a conduit.

neil

[jddevel]

Thanks Neil. Ducted with a string pull available just in case need to add another cable. But your helpful thanks.

[NMEA]

On 2017-5-11 at 11:37, Tony Brooks said:

Yup - 50mm separation or one in conduit I think.

Depends, if you are for instance using three core then it would be fine for ISO BS EN 13297 and RCD but not if you were using conduit wire, it's the sheath that makes the difference