over specifying a common mode choke? (current)

[SArepairman]

How much % over-rating should be given to a common mode mains filtering choke maximum current?

[SeanB]

Whatever the fuse rating is, and go one size up. It will run cooler. Those ratings given in the spec sheet are always going to be optimistic, so it pays to overrate the filter. If it is less than 5A use a 6A one anyway, there is little difference going below this.

[T3sl4co1l]

If you mean by dynamics, it probably won't make a difference.  It's a thermal thing.

Beware that some parts may be sensitive to differential current anyway.  Multi-aperture cores come to mind (Laird makes these ferrite-block 'array' chokes, which are probably sensitive in this way).  Toroids are / should be, too, but I don't know how to estimate by how much; probably little enough not to worry.

Tim