On Tue, 24 Apr 2018 12:38:02 +0100, wrote:

All these fuses will say 415V and are generally 100A, although sometimes less. This doesn't mean it's three-phase, unless there are three of them

The 415V is just the voltage the component is rated to €” fuses operate on Amps alone, the voltage is not relevant. A 100A fuse will blow just beyond 100A whether it's at 12V or 1200V.

The same way appliance mains cables are rated to 300V or even 600V; it just refers to the insulation resistance or safety factor of the cable.

I guess it's so they can be used in 3 phase setups. A short from L1 to L2 could put 415V across one of the fuses.

--
During the weekly Lamaze class, the instructor emphasized the importance of exercise, hinting strongly that husbands need to get out and start walking with their wives.
From the back of the room one expectant father inquired, "Would it be okay if she carries a bag of golf clubs while she walks?"