wiring harness

[derek]

When making up a wiring harness, what size cable should be used. Cross section or amperage please.

 

[Comet Rider]

Wiring CSA

Hi Derek,

I typically use the following;

1/ Dynamo/Alternator and battery feeds along with main earth wires 2.5mm Sq rated at 30A continuous.
2/ All other wiring 24/0.2mm which is rated at 7A continuous.

One point to note is that I recomend running an addition earth wire up into the head light shell, and then having 1 common point near to the battery and charging medium

I also use various colours to help with identifying faults or problems at a later date, and also I use high quality waterproof connectors

Best of luck
Neil

 

[pifinch]

Hi Derek,

I typically use the following;

1/ Dynamo/Alternator and battery feeds along with main earth wires 2.5mm Sq rated at 30A continuous.
2/ All other wiring 24/0.2mm which is rated at 7A continuous.

One point to note is that I recomend running an addition earth wire up into the head light shell, and then having 1 common point near to the battery and charging medium

I also use various colours to help with identifying faults or problems at a later date, and also I use high quality waterproof connectors

Best of luck
Neil

Just being old fashioned I would be worried about using 0.2mm wire anywhere due to its lack of flexibility, lack of substantial sheath plus suitable safety margin, cos I'm scared of derating I dont think I would use anything less than .75mm. (not a criticism cos Im over cautious & ride like an old lady anyway!)

 

[Comet Rider]

Explanation of CSA

Just being old fashioned I would be worried about using 0.2mm wire anywhere due to its lack of flexibility, lack of substantial sheath plus suitable safety margin, cos I'm scared of derating I dont think I would use anything less than .75mm. (not a criticism cos Im over cautious & ride like an old lady anyway!)

24/0.2 means that it is 24 strands of 0.2mm diameter wire which equates to 0.75mm CSA. I always use multi strand wire, as you rightly say, it is more flexible. I buy my wire either from Maplin electronics who sell short 10M lengths of Rapid Electronics who will sell 100M rolls...

Neil

 

[clevtrev]

When making up a wiring harness, what size cable should be used. Cross section or amperage please.

6 volts or 12 ???

 

[derek]

6 volts or 12 ???

Thanks for the advice, 12 volts.Derek

 

[Comet Rider]

Cable ratings

Hi Trev,
All the cable I spec is tri-rated 240 VAC rated cable, so is more than capable of handling anything either 6 or 12V DC can throw at it, including 60/55W headlight bulbs

Cheers
Neil

 

[pifinch]

Hi Trev,
All the cable I spec is tri-rated 240 VAC rated cable, so is more than capable of handling anything either 6 or 12V DC can throw at it, including 60/55W headlight bulbs

Cheers
Neil

Hi Neil, I was not being critical questioning your size of cable, but I saw you were quoting .75mm, the .75mm tri rated cable I get from R.S. is quoted as 14A @240 AC, so I suppose low voltage DC will handle less current? I'm not sure as I tend to always over engineer! (This is the person who runs 22mm cables for anything over 60A!)

 

[timetraveller]

A suggestion following Cometrider's remarks above. If one has one of our car alternator kits on a solo then I recommend using a 130/90 watt headlamp bulb. That willl take 11 amps so use the 30 amp cable all the way to the headlamp and make sure that your dipswitch will take it. Some of the old 1950s style cheap dipswitchs will not take 10/11 amps. If you have more than one headlamp, eg spot lights or an extra headlight on a sidecar then 60/55 bulbs will be ok but you still need to check your dipswitch.

 

[Tnecniv Edipar]

cable I get from R.S. is quoted as 14A @240 AC, so I suppose low voltage DC will handle less current? I'm not sure as I tend to always over engineer!

The 240 volt AC rating refers to the insulation quality. For the same power , reducing voltage increases current. Power = volts x amps. Thats why a 12 volt system on vehicles is better than 6 volt , less amps for the same watts so less loss via resistance and consequent heating effect in wiring and switches.

 

[Tnecniv Edipar]

Some of the old 1950s style cheap dipswitchs will not take 10/11 amps.

A solution to that problem is to use the dip , light switches etc through a relay discreetly hidden in the headlamp shell. The relay only requires a few hundred milliamps to activate and it's contacts handle the heavy current.

 

[timetraveller]

For those who care the heating effect with a DC current is I squared R where I is the current flowing and R is the resistance. So halving the current gives one quarter of the heating effect while conversely doubling the current give four times the heating. A faulty connector etc which introduces an extra resistance into a circuit gets hot. You knew that didn't you? Change from an original 6v 36 watt headlight passing 6 amps to a 12 volt 60 watt headlight and you have only 5 amps passing through the circuit. This gives a heating ratio of 36 to 25 i.e. about a third less heating. Go for a 130 watt bulb and you have 11 amps. 6 amps squared is 36 heating units and 11 amps squared is 121 meaning that you have about 3.4 times more heating. Decent cables and dip switches are needed.

Just had a good day at the Pie and Pint and nice to see you all there.

 

[Riggles]

Riggles

I made my loom using a length of trailer flex, which contains 5 or 7 colored wires. I don't know what section or amps it is, but it works OK with 12 volts on the Rapide. As for the 130/90 globes, forget them & go for the 60/55 Plus 50% Phillips globes.