Wire Sizeing.

[stuart.munroe]

I am considering rewiring my 1936 VG - can anyone give me some advice on which wire size I need?
Thanks
Stuart

[Bob.Murphy]

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.

[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.

[stuart.munroe]

Thanks for the help, I plan to use modern braided wire which looks original.

[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?

[roger.fellows]

Hi Stuart, usually measured as the cross-section area of the conductor.
Somebody will correct me if I'm wrong.

Roger

[Bob.Murphy]

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.

[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.