12 volt cable

[kevinshaw]

hello all

ive just bought my first narrow boat after living in a river cruiser for a while.

the 12 volt wiring has been done with household single core so i need to change this to multi strand

what size cable do i require everything runs through an inverter at the minute with no faults at present

thankyou for any help you can give

[Tiggs]

Although single core cable is not permitted for CE compliance I don't think the BSS forbids it.

 

You need to work out the maximum current to determine the thickness of cable needed.

Edited November 8, 2015 by Tiggs

[kevinshaw]

that interesting as ive been told single core is not allowed due to vibrations ??

[ditchcrawler]

that interesting as ive been told single core is not allowed due to vibrations ??

Its not a good idea shall we say. maybe not against the rules but then nor is a 1mm thick hull

[andyb116]

When i questioned this with the man that wrote the BSS, he said that even though they don't like twin and Earth (vibration) it's not actually against the rules.

[kevinshaw]

Its not a good idea shall we say. maybe not against the rules but then nor is a 1mm thick hull

sweet . one less job to do straight away

[ditchcrawler]

sweet . one less job to do straight away

If it was me I wouldn't put it off for to long

[jonathanA]

hello all

ive just bought my first narrow boat after living in a river cruiser for a while.

the 12 volt wiring has been done with household single core so i need to change this to multi strand

what size cable do i require everything runs through an inverter at the minute with no faults at present

thankyou for any help you can give

[jonathanA]

Just reading your post I think everyone has assumed your talking about the mains voltage cabling (inverter output) but you do say 12v wiring. For your mains cabling the usually accepted cable is blue artic flex at 2.5mm or 1.5mm. If you have standard domestic t&e cable then as said it is not recommended as it can (can not will) fracture due to vibration. Put it on your to do list...

 

Eta sorry mobile phone post didn't quite work

Edited November 8, 2015 by jonathanA

[Detling]

A Friend of mine has some twin core and earth solid domestic cable installed when he fitted out the boat in 1978, before rules came about. Still working no problems ever, he has just fitted his third engine as the previous two have died of old age as the boat is shared and typically cruises for 24 weeks and some 700 miles per year, so plenty of vibration.

[alan_fincher]

Nobody has mentioned the ambiguity that you say "everything runs through the inverter", but ask about 12 volt cabling.

 

So what voltage is in the cables you are talking about, because if they are coming out of an inverter it will not be 12 volts.

[Murflynn]

that interesting as ive been told single core is not allowed due to vibrations ??

It is not allowed under the RCD requirements.

Nothing to do with BSS.

However please do bear in mind that a fault in a 12v wire may cause a fire, because of the high currents associated with low voltage systems, whilst the equivalent risk in a 240v wire carrying the same power load is much less. Vauxhall Zafira .................. ?

Edited November 9, 2015 by Murflynn

[Chewbacka]

No one seems to have answered your question for cable size.

At 12v the main concern is voltage drop not cable current carrying capability.

For this you need to consider the peak load and cable length to ensure that enough voltage is available to the appliance for correct and efficient operation.

Cable calculators are now available on line such as these below - I have never used them as I made my own spreadsheet a few years ago.

Also don't forget the cable run is there and back again which some calculators allow for and some don't.

 

 

http://www.12voltplanet.co.uk/cable-sizing-selection.html

or

http://www.solar-wind.co.uk/cable-sizing-DC-cables.html

 

Have fun with them.

[jonathanA]

Nobody has mentioned the ambiguity that you say "everything runs through the inverter", but ask about 12 volt cabling.

 

So what voltage is in the cables you are talking about, because if they are coming out of an inverter it will not be 12 volts.

see post #9

[kevinshaw]

thank you all for the replys sorry for the delay in replying {i work away }

i will have a good read tomorrow and come back with more questions

 

my 12 volts do come out of the inverter they are connected to the same cables that charge my batteries

i have a combined inverter / 4 stage battery charger power pack

[blackrose]

A Friend of mine has some twin core and earth solid domestic cable installed when he fitted out the boat in 1978, before rules came about. Still working no problems ever, he has just fitted his third engine as the previous two have died of old age as the boat is shared and typically cruises for 24 weeks and some 700 miles per year, so plenty of vibration.

An interesting anecdote, but it has no bearing on whether another boat fitted with solid cables would have problems. Safety regulations and recommendations are based on documented accidents and problems, as well as testing and statistical probability, but never on a single example.

Edited November 12, 2015 by blackrose

[Guest]

An interesting anecdote, but it has no bearing on whether another boat fitted with solid cables would have problems. Safety regulations and recommendations are based on documented accidents and problems, as well as testing and statistical probability, but never on a single example.

It is a tricky one. I have seen domestic twin and earth cable used (not necessarily ideally) in far worse conditions than would ever be met on a canal boat, yet it survived. The worst I remember was it had been used to feed a compressor instead of flexible cable.

Now I know it is not recommended on boats, but I remember the Isle of Man ferries used MICC cable, which is basically single strand cable.

I would only use it for a lash up personally perhaps temporary to test something out.

[ditchcrawler]

 

Now I know it is not recommended on boats, but I remember the Isle of Man ferries used MICC cable, which is basically single strand cable.

 

That use to be a real pain with vibration

[Guest]

That use to be a real pain with vibration

I often wondered about the wisdom of using it. I'll guess it used to crack on bends?

 

MICC was always going to be the wonder cable, but many installations we came across in buildings had failed. How much of this was down to poor termination technique is hard to say. Certainly found a few where the compound had been incorrectly applied.

Edited November 12, 2015 by Guest

[ditchcrawler]

I often wondered about the wisdom of using it. I'll guess it used to crack on bends?

 

MICC was always going to be the wonder cable, but many installations we came across in buildings had failed. How much of this was down to poor termination technique is hard to say. Certainly found a few where the compound had been incorrectly applied.

What got me was all our emergency systems were in MICC, Lights, Alarms, tannoy etc. to be fire proof, You can guess the problems vibration caused.

[Guest]

What got me was all our emergency systems were in MICC, Lights, Alarms, tannoy etc. to be fire proof, You can guess the problems vibration caused.

Using a powder insulated cable in an area prone to vibration certainly doesn't seem practical!

[alan_fincher]

I have been systematically removing cables based on solid drawn conductors as we refit the "new" boat.

 

For original 230V AC it has plenty of T&E still present, although most is actually not connected to anything, simply being left behind linings by a previous owner.

 

However the lion's share of the active 12 volts wiring was also in solid drawn cable, but mostly single cables with no outer sheath.

I have to say that I found absolutely no hint of any damage or any cable ends that looked vaguely close to fracturing by the point I removed them. This despite much of it not really being supported with any kind of clips - loads of it just hanging loose from connection points.

 

Also much of this cabling (both the 230V AC T&E, and the unsheathed 12V) , was lying against polystyrene insulation. In many cases the claimed symptom of cabling being in direct contact with polystyrene had resulted in it becoming embedded in it, such that it can then be peeled out leaving a channel. However, completely contrary to many claims, the the outer surface of the removed cable (whether the sheath, or a single layer on an unsheathed cable) was always in near-pristine undamaged condition. This surprised me, but I found not one hint of any partial failure whatsoever.

All this cabling has been in place for a minimum of 20 years I think.

So from a not particularly scientific survey of one single boat, I conclude that worries about both use of solid drawn cables, and also cables in contact with polystyrene seem unfounded. Of course it is possible different types of cable and different types of polystyrene might yield a different result.

We plan to replace the lot, eventually - not just the cables, but insulation too, but I see nothing that indicates an urgent need to do so.

[ditchcrawler]

.

 

 

Also much of this cabling (both the 230V AC T&E, and the unsheathed 12V) , was lying against polystyrene insulation. In many cases the claimed symptom of cabling being in direct contact with polystyrene had resulted in it becoming embedded in it, such that it can then be peeled out leaving a channel. However, completely contrary to many claims, the the outer surface of the removed cable (whether the sheath, or a single layer on an unsheathed cable) was always in near-pristine undamaged condition. This surprised me, but I found not one hint of any partial failure whatsoever.

 

All this cabling has been in place for a minimum of 20 years I think.

 

So from a not particularly scientific survey of one single boat, I conclude that worries about both use of solid drawn cables, and also cables in contact with polystyrene seem unfounded. Of course it is possible different types of cable and different types of polystyrene might yield a different result.

 

I always found that but I dont know what unseen damage it does if polymers leech to/from the insulation

Edited November 12, 2015 by ditchcrawler

[Guest]

I have been systematically removing cables based on solid drawn conductors as we refit the "new" boat.

 

For original 230V AC it has plenty of T&E still present, although most is actually not connected to anything, simply being left behind linings by a previous owner.

 

However the lion's share of the active 12 volts wiring was also in solid drawn cable, but mostly single cables with no outer sheath.

 

I have to say that I found absolutely no hint of any damage or any cable ends that looked vaguely close to fracturing by the point I removed them. This despite much of it not really being supported with any kind of clips - loads of it just hanging loose from connection points.

 

Also much of this cabling (both the 230V AC T&E, and the unsheathed 12V) , was lying against polystyrene insulation. In many cases the claimed symptom of cabling being in direct contact with polystyrene had resulted in it becoming embedded in it, such that it can then be peeled out leaving a channel. However, completely contrary to many claims, the the outer surface of the removed cable (whether the sheath, or a single layer on an unsheathed cable) was always in near-pristine undamaged condition. This surprised me, but I found not one hint of any partial failure whatsoever.

 

All this cabling has been in place for a minimum of 20 years I think.

 

So from a not particularly scientific survey of one single boat, I conclude that worries about both use of solid drawn cables, and also cables in contact with polystyrene seem unfounded. Of course it is possible different types of cable and different types of polystyrene might yield a different result.

 

We plan to replace the lot, eventually - not just the cables, but insulation too, but I see nothing that indicates an urgent need to do so.

Pretty much my mate's story when he sold his boat. The old twin and earth cable seemed OK. I do think there is an element of luck involved with cable though. We used to get batches of cable where the copper was really hard and would be difficult to bend, as though it hadn't been annealed properly. The cable in my neighbour's house is like this, and removing switches etc for decorating leads to cables snapping. I wouldn't be surprised if such poor cable had founded the reputation for single core cable being unsuitable.

[Theo]

Pretty much my mate's story when he sold his boat. The old twin and earth cable seemed OK. I do think there is an element of luck involved with cable though. We used to get batches of cable where the copper was really hard and would be difficult to bend, as though it hadn't been annealed properly. The cable in my neighbour's house is like this, and removing switches etc for decorating leads to cables snapping. I wouldn't be surprised if such poor cable had founded the reputation for single core cable being unsuitable.

 

I wonder if this was to do with the installer being rather cavalier about bending and rebending the cables. Copper work hardens very quickly.

 

N