315mA Fuse standard what are its origins?

[PICmonster]

Hi There

I have had this question in my mind for some time and I have not really had a proper explaination, the question is simple.
Where did the 315mA fuse standard come from, what are its origins and why so specific and not a round number, is there an equation related to this?

[tom66]

Part of the Renard "10" series (a preferred number series.)

R10: 1.00  1.25  1.60  2.00  2.50  3.15  4.00  5.00  6.30  8.00

Renard's system of preferred numbers divides the interval from 1 to 10 into 5, 10, 20, or 40 steps. The factor between two consecutive numbers in a Renard series is constant (before rounding), namely the 5th, 10th, 20th, or 40th root of 10 (1.58, 1.26, 1.12, and 1.06, respectively), which leads to a geometric sequence. This way, the maximum relative error is minimized if an arbitrary number is replaced by the nearest Renard number multiplied by the appropriate power of 10.

[PICmonster]

Thank you very much I have wondered about this for a while.