Two identical barrel jacks. One rated for 2.5A the other for 5A. Why?

[Starlord]

http://www.cui.com/product/resource/pj-102a.pdf
http://www.cui.com/product/resource/pj-102ah.pdf

The only apparent physical difference between these two jacks is that the solder terminals on one are plated in tin, and the other in silver.  The specified resistances are the same, the plating of the barrel itself is the same.  Yet the tin one is rated for 16V 2.5A, and the silver one is rated for 25V 5A.  Why?  Does tin break down at high currents / voltages?

[Lightages]

I would hazard to guess they are identical except for the plating. One was probably designed and manufactured to a specification of one customer or the engineering department and the other relabeled to meet the specs of another client. This happens all the time with components.

[T3sl4co1l]

Good question... ask them.

Connector current rating is a pretty dubious thing, anyway.  Contact resistance is all over the damn place, so estimating temp rise at some current capacity is almost absurd.

0.1" pitch headers, for example, aren't normally rated beyond 2-3A, but you can find ones rated for 4-6A.  And those ratings, in turn, are usually "per pin", meaning, not just for one pin at a time, but just one pin, exclusive.  They don't always/usually mention what total current rating would be for all pins wired.  Let alone if you wire pins in parallel, and hope that the current shares!

It is curious that it's such a large difference (a factor of 2!) for absolutely no identifiable reason.  I notice they don't specify the terminal thickness in either case.  Which could maybe be different, but yeah... they probably are the same damn thing, plating only.

I suppose the moral of the story is:
See a factor of two advantage?  Take two backwards and call that a safe maximum!  (I.e., 2.5 or 5A?  Hell no, we're calling it 1.25A, tops!)

Tim

[Psi]

one is tin plated and the other is silver plated.

[Rufus]

It is curious that it's such a large difference (a factor of 2!) for absolutely no identifiable reason.

Lumberg make a panel mount jack 1614 09 rated at 0.5A and <30m ohm resistance.

CUI make a cable mount jack PR-002A which looks identical apart from different style solder tags and a PVC strain relief instead of a nut. The PR-002A is rated at 4.0A and <50m ohm resistance.

Max current and worst case resistances give power dissipation different by a factor of 107!

From this one can deduce that current ratings for this type of connector are made up crap with Lumberg at one end of the spectrum of crap and CUI at the other.