Cable/wiring rating

[kentishvanman]

Hi,
On the wiring at the rear of the control/distribution panel there are some short lengths of single core cable/wire. For example connecting the water pump switch fuse to the printed circuit. This particular one had broken off the circuit hence the water pump stopped working.
Have solved the problem by bypassing the printed circuit and all is fine.
There are no cable ratings given for these stretches of wire on the wiring diagram so how are they rated. Can they be compared to multi strand cable?

[Mocki]

Because of the smaller cross section area , single strand can carry less than multi strand , so if you replace with multi strand of the same overall size , you will be fine

[kentishvanman]

Hi

Because of the smaller cross section area , single strand can carry less than multi strand , so if you replace with multi strand of the same overall size , you will be fine

Thanks for that.
I did consider re soldering but that would mean removing the printed circuit plus other bits and then hot iron on circuit could lead to problems. My 'mod' works so what else can I ask for.
Thanks again.

[itchyfeet]

single strand can carry less than multi strand

Other way

BS7671 states you must derate stranded cables by 5% over solid of the same CSA.

unless I misunderstood?

[Pinkythelabrat]

single strand can carry less than multi strand

Other way

BS7671 states you must derate stranded cables by 5% over solid of the same CSA.

unless I misunderstood?

I think you are right Itchy - if the overall copper conductor is the same diameter the multi core will inevitably have small gaps between strands and so will have less ‘room’ for conducting than a solid would.

Multi core are more flexible but less conductive otherwise all wiring would be multi core rather than the solid copper seen in houses.


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[Mocki]

Well when I was being taught ( many years ago )
stranded wire carries more current than solid wire due to lower resistance. ... Thus due to extra surface area more surface current flows , however there is a point when you are using uhf that the opposite becomes true , but at DC stranded carried more ....

Either way it’s a negligible amount at 12v dc

[itchyfeet]

Either way it’s a negligible amount

agreed

[Pinkythelabrat]

*hangs head*
I shall stick to chemistry...


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[bigherb]

single strand can carry less than multi strand

Other way

BS7671 states you must derate stranded cables by 5% over solid of the same CSA.

unless I misunderstood?

Yes you did. Multistrand cables carry more current than solid core. The more strands for a given mm2 the more current it can carry. Don't confuse household electrics with auto wiring.

[tobydog]

AC/DC

[itchyfeet]

Yes you did. Multistrand cables carry more current than solid core. The more strands for a given mm2 the more current it can carry. Don't confuse household electrics with auto wiring.

How does a wire know know if it's in a vehicle or a fixed installation

The derating in BS7671 is for bundles of cables for thermal reasons which I assume also applies in vehicle electrics.

The current capacity of a wire depends on so many factors including the insulation type and really comes down to thermal characteristics. too much current it gets too hot.

Steve has it right

Either way it’s a negligible amount