2core automotive V 2core flex

[jc69817]

Hi guys. I was wondering if I could use standard 2core flex to run some additional lights in a van or is there something special about the automotive cable besides the massive price.
I was thinking brown to pos blue to neg instead of red to pos black to neg

Thanks guys

 

[Jackrae]

Core diameter generally insufficient, fewer strands in equivalent core diameters so less flexibility, PVC insulation is not heat proof, insurance companies just love DIY botches to name but a few

 

[rsgaz]

2core flex

The whole vehicle's body is the negative connection. You don't need to buy two core flex for any of it.

You just run a single core from wherever you're picking up the 12v(fused of course), then to the switch, then to the lamp. Then you only need a short wire for the negative to the nearest available negative connection on the vehicle's body. You can even drill your own if you are feeling confident.

That's exactly how the vehicle's loom is already wired, with single cores in a loom, cable tied and/or taped together.

Some silicone wire would be perfect.

 

[aptsys]

Some silicone wire would be perfect.

Silicone wire is great for flexibility and high heat applications, but it's notoriously easy to damage. Standard PVC singles are fine.

 

[ban-all-sheds]

The whole vehicle's body is the negative connection.

Depends how old it is.

That's exactly how the vehicle's loom is already wired, with single cores in a loom, cable tied and/or taped together.

Depends how new it is. Although that's an "AIUI".

 

[jc69817]

Thanks for the replies guys
It’s going to be a micro camper so was going to use an earthing bar near the fuse box/leisure battery hence the 2 core. So would .75mm^2 be ok or should I bite the bullet and buy the black/red stuff.

 

[ericmark]

The main difference between PVC flex and automotive cable was the ability to withstand oil and chafing. Today engines don't become anointed like in the old days, I used harness tape, like insulating tape but no glue on it, as the glue would go all sticky and slip once wet with petrol or oil, only used insulation tape on the ends.
As to size it was 14/0.012 in my day so uncertain as to what size you need, however cable rating for auto use seemed to be higher then when using same cable for domestic.

 

[EFLImpudence]

It’s going to be a micro camper so was going to use an earthing bar near the fuse box/leisure battery hence the 2 core.

As said, the vehicle body is the negative conductor so 'earth' bar is not necessary.
To what would you connect it?

Hence you don't need 2 core, nor sheathed, so price halved or more.

So would .75mm^2 be ok

Yes, for up to 6A at least; some says 14A.

or should I bite the bullet and buy the black/red stuff.

The colour is irrelevant.
Different colours are used to distinguish between several that are run together.
There are many colours and stripes.

I was thinking brown to pos blue to neg instead of red to pos black to neg

Some manufacturers use brown as the negative to the ground connection.

 

[ban-all-sheds]

is there something special about the automotive cable besides the massive price.

I bet that if you bought short lengths of any cable on little plastic spools in Halfords it would have a massive price....

 

[ban-all-sheds]

Hence you don't need 2 core, nor sheathed, so price halved or more.

I'd not trust unsheathed "fixed wiring" cable, no matter how multi-stranded and flexible, in an automotive environment because of the thickness of the insulation. Or rather the thinness of it.

 

[ericmark]

I have not seen the old Lucas colours used on cables for years, brown = unfused live all the time, Purple = fused live all the time, White = unfused from ignition switch, and Green fused from ignition switch. Then there were tracers left and right hand indicators for example think was white and red but a long time again.
Bosch used all black wires with numbers 30 live 31 chassis etc. 273 and 274 indicators from memory.
Neither system used red for live. Seem to remember Bosch red was speaker wires, white chassis?
When I rewired the number of reels needed to get all the right colours meant easy way was 7 core cable, so used caravan wiring codes, white is always chassis or return as often white is a thicker cable than rest.

 

[jc69817]

I bet that if you bought short lengths of any cable on little plastic spools in Halfords it would have a massive price....

True but comparing 50m rolls the difference is massive

 

[ban-all-sheds]

Tri-rated?

 

[SimonH2]

Automotive wire often had thinner, harder insulation - and a higher current rating for a given CSA. The difference in size (and hence bulk of a loom) between "thinwall" and ordinary stranded wire (which I've also used) is quite considerable for a given current rating.
Eg, 1mm² stranded cable is given a rating of 8.75A, while the same CSA in thinwall is rated at 16.5A - so almost twice the current rating and a thinner cable.
BTW - I can recommend Vehicle Wiring Products for ... as the name implies ... stuff for vehicle wiring.

 

[Harry Bloomfield]

I will just add that it is not entirely current rating which needs to be considered, but voltage drop too. The longer the cable, the greater the voltage drop and as the voltage is so low (12v) to begin with - a small drop becomes a large percentage.