Thin walled cabling

[jddevel]

I need more advice please. Another question. Although thin walled cable apparently is said to be better performing is that marketing "speak" as it may be cheaper to produce and is there any reason why it should not be used in the narrowboat environment ?

[Robbo]

It's not marketing speak.  If you put cables in a conduit you reduce its capacity as the cables get warmer.  Thin walled is less insulation, etc and the spec of the cable is in open air.   

[jddevel]

Thanks Robbo. I`m just too cynical sometimes for my own good. Apart from the macerator toilet I`m installing which specifies 6mm2 is there any other 12v "domestic" appliance I`m likely to "need" using that size cable. I`m trying to work out the number of metres-there and back. 

[Robbo]

Just now, jddevel said:

Thanks Robbo. I`m just too cynical sometimes for my own good. Apart from the macerator toilet I`m installing which specifies 6mm2 is there any other 12v "domestic" appliance I`m likely to "need" using that size cable. I`m trying to work out the number of metres-there and back. 

I would over spec the toilet and fridge and pumps.  Unless short lengths I would actually increase to 10mm2.

[jddevel]

Thank you again Robbo. Will do.

[Tony Brooks]

For others as well as the OP.

In my opinion the marketing for thin wall/tri-rated cable is little short of a con for boat use. The cable needs to be specified to minimise voltdrop along the run NOT the quoted current carrying capacity. For this its the conductor cross sectional area that is important and lo and behold the CCSA for "ordinary" and thin wall cable is the same for any given size so both create the same voltdrop.

I am not even sure 6 sq mm CCSA would be large enough for a toilet towards the front of a full length boat.

My advice - ignore "thin wall" and buy on CCSA.

[Keeping Up]

Surely if the cable size is being specified to minimise volt drop, as is usually the case on narrow boats, rather than being near it's maximum current carrying capacity, then the overall diameter of the cable will be less with thin walled cable. If conduit space is limited then in these circumstances the use of thin walled cable will be an advantage.

[IDS]

Thin walled is probably also more susceptible to mechanical damage as in general boat wiring (in my experience) is not run in conduit.

[Tony Brooks]

43 minutes ago, Keeping Up said:

Surely if the cable size is being specified to minimise volt drop, as is usually the case on narrow boats, rather than being near it's maximum current carrying capacity, then the overall diameter of the cable will be less with thin walled cable. If conduit space is limited then in these circumstances the use of thin walled cable will be an advantage.

That is certainly and advantage in automotive applications, which I suspect is what drove its development but I have no noticed an significant requirement for minimising cable size in the boats I have been involved with. Just use a larger or different profile conduit, but having said that I find in the inland sector often wiring is not in conduit.

[Keeping Up]

4 minutes ago, Tony Brooks said:

That is certainly and advantage in automotive applications, which I suspect is what drove its development but I have no noticed an significant requirement for minimising cable size in the boats I have been involved with. Just use a larger or different profile conduit, but having said that I find in the inland sector often wiring is not in conduit.

On my boat there is plenty of room in the actual conduit but a definite shortage of space where the cabling passes through bulkheads etc.

[WotEver]

Simply put, thin-wall has a smaller diameter for the same ccsa. If that offers an advantage for your install then by all means use it. If you have plenty of room then save some money and buy the standard stuff. 

The copper that carries the current is the same in both cases.