Cable spade end cross sectional area.

[driver0606]

I am surprised to find that engine start/bowthruster cables may have spade ends that have a cross sectional area less than the cable itself. For example, a cable, supplied by a cable company, of 70mm2, has spade ends of 3mm by 16mm section, i.e. 48mm2. This seems inadequate.

Am I missing something?

 

[Croftie]

48mm2 should be good for around 350amp and that is over a very short distance. Having a larger 70mm2 cable is probably to minimise volt drop over a longer distance.

 

[Lon nan Gruagach]

I am surprised to find that engine start/bowthruster cables may have spade ends that have a cross sectional area less than the cable itself. For example, a cable, supplied by a cable company, of 70mm2, has spade ends of 3mm by 16mm section, i.e. 48mm2. This seems inadequate.

Am I missing something?

Yes...
Cable cross section and current capacity is down to how much you can stuff through it before it either boils or wastes too much oomph.
Now, the spade connector is only a very very short part of the circuit, so volt drop is virtually insignificant.. try it on one of the online volt drop calculators and enter 0.005m for the cable length.
Also the connector is firmly connected (it better had be) to some large chunks of copper and other metal. These lumps can easily dissipate the heat from the spade.
Not only that (this is staring to sound like the shopping channel, bleagh), not only that but also the spade is not wrapped up in insulation, so it has higher current capacity per cross-section than a wire with a thermal blanket wrapped round it (namely insulation).

So, I guess that might be 3 somethings all wrapped up in 1.

 

[superheat6k]

With cable end lugs it is more important to consider the tightness and method of affixing the lug, and then that the lug is tight to its mating component. All strands cut neatly with no strays left outside the lug, and the lug of the correct CSA for the cable concerned. Hydraulic crimpers for up to 70mm2 are available for less than £30. On any cable the lug should not move with considerable pulling proportional to the cable size. For exposed conductors, e.g, the business end of a windlass connection, filling the tiny voids around each strand with solder is well worth while.

 

[driver0606]

Thanks, guys.

 

[prv]

Hydraulic crimpers for up to 70mm2 are available for less than £30. On any cable the lug should not move with considerable pulling proportional to the cable size. For exposed conductors, e.g, the business end of a windlass connection, filling the tiny voids around each strand with solder is well worth while.

If it's correctly crimped there will not be any "tiny voids".

Pete

 

[superheat6k]

If it's correctly crimped there will not be any "tiny voids".

Pete

The strands are round bearing up against each other, there will be voids, albeit very small.

 

[prv]

The strands are round bearing up against each other, there will be voids, albeit very small.

If they’re still round after being “crimped”, then they weren’t actually crimped.

Pete

 

[Lon nan Gruagach]

If they’re still round after being “crimped”, then they weren’t actually crimped.

Pete

Should look like this