Directional

When it comes to directionality I find myself a bit lost. Let's take for example an AC power cable. Directionality is easy because each of the two connectors is different. But a fuse? Perhaps someone can help me understand how a fuse connecting the AC input of our equipment to the wall power can have directionality. Most aftermarket fuses have arrows indicating direction and it is said the construction is different at each end. Fair enough, but which end is the right end and right for what? An AC power source alternates between plus and minus 50 to 60 times a second. Which direction is right? Imagine a pendulum. Does it matter if it begins from left to right or right to left? I have in the past bought into interconnect directionality. Here we too have an alternating current signal. But now the story goes it's the wire's directionality when it is being drawn out of the die that the copper was pulled through, thus realigning the crystal structure in such a way as to make it sound better or worse depending on source or receiver side. This argument still befuddles me but I have consistently heard differences in an RCA interconnect. At least I think I have. Without reconstruction this cannot be tested in an XLR or AC power cable (the male and female connectors define its source). But a fuse? Color me confused.