Page 1 of 1
Wire Sizeing.
Posted: Thu May 05, 2016 9:12 pm
by stuart.munroe
I am considering rewiring my 1936 VG - can anyone give me some advice on which wire size I need?
Thanks
Stuart
Re: Wire Sizeing.
Posted: Thu May 05, 2016 9:46 pm
by Bob.Murphy
stuart.munroe wrote:I am considering rewiring my 1936 VG - can anyone give me some advice on which wire size I need?
Thanks
Stuart
Stuart,
Are you going 'original' with a 6 volt system, or moving to 12 volts??
For a given Wattage, a 6 volt system will pass twice the current (Amps) of a 12 volt system and its Amps that generate heat. Its safer to go with heavier wiring on a 6 volt system.
I'm not sure which 'square mm' specification is appropriate off hand, I'll have a look at my bikes tomorrow.
Bob.
Re: Wire Sizeing.
Posted: Fri May 06, 2016 6:30 am
by simon.holyfield
You'll find that the choice is more about what looks appropriate. Old bike wiring doesn't carry much current - no starter, no big alternator - so 2.5 mm is plenty for most circuits.
The issue is that insulation is much thinner than in the past, and looks very modern. I used a 2.5 mm rubber cable intended for solar panels which I think looks better.
Re: Wire Sizeing.
Posted: Fri May 06, 2016 6:49 am
by stuart.munroe
Thanks for the help, I plan to use modern braided wire which looks original.
Re: Wire Sizeing.
Posted: Fri May 06, 2016 9:35 pm
by stuart.munroe
Thanks Bob I plan to leave it on 6 volt. Is 2.5mm suitable and is that the wire diameter rather than the outside diameter of the complete cable?
Re: Wire Sizeing.
Posted: Fri May 06, 2016 9:59 pm
by roger.fellows
Hi Stuart, usually measured as the cross-section area of the conductor.
Somebody will correct me if I'm wrong.
Roger
Re: Wire Sizeing.
Posted: Fri May 06, 2016 10:13 pm
by Bob.Murphy
stuart.munroe wrote:Thanks Bob I plan to leave it on 6 volt. Is 2.5mm suitable and is that the wire diameter rather than the outside diameter of the complete cable?
2.5mm is the cross-sectional area of the copper wire inside the insulation. That is quite large for a 6volt system with a charging current of about 10Amps (60 Watts). It will therefore be fine tor this purpose.
2.5 sq/mm is the size of wire in a domestic ring main where a pair of wires (i.e. both paths in a ring) can happily carry 32 Amps. That isn't quite comparable to a D/C bike circuit as the characteristics of an A/C circuit are slightly different in terms of current and heat generation, but it does indicate that you are well on the 'safe side'.
You can get more that 10 Amps from a battery, depending on what you are connecting to it, so make sure you incorporate a fuse or two

.
Bob.
Re: Wire Sizeing.
Posted: Sat May 07, 2016 6:17 pm
by paul.jameson
If you go to
http://www.autoelectricsupplies.co.uk/p ... ategory/12 you will find the information you need to select the cable you want.