Determining current flow to install "audiophile" fuses.

"  It’s why many boutique cable manufacturers have been putting directional arrows on their cables for twenty five years. Hel-loo!"

...and 25 years ago no one gave a damn about direction on signal cables
...and 25 years ago no one gave a damn about 5 cm long fuse sound quality or "upgrading" fuses
...35 years ago we had detailed instruction manual given with detailed diagrams and schematics on each component we purchased. Now they all say "don't get in or you get killed".

Evolution has reached its peak back than -- now it's indeed Devolution, degradation and retardation. Everything and everyone around you will say you're treated as idiot! The funny thing is that everyone likes it and feels happy about it thus motivating and promoting devolution. Maybe some day we'll become again Neanderthals. 

Its probably a safe assumption that most people still do not care about fuse sound or wire direction. Including me for the most part.

Of course some care more. May the force be with them.

Now I must say I have some Monster Cables around still that do have arrows on them indicating which way to hook them up so I obligingly do since they took the time to say so even though I do not know why it matters. I also do that with MIT cables with network boxes that are clearly not the same on both ends.

But if a respected maker claims a directional product but neglects to clearly instruct users about the recommended orientation then that product has little credibility with me at least. You took the time to make a "directional product" but neglected to provide clear instructions on proper setup? Give me a break. I’ll find another vendor that has better attention to details that supposedly matter.

I read somewhere that only the direction of the ac [in a fuse...or power cord for that matter] towards the business end of the component[what is heard] is of any value in directional break-in ,hence, the reason there is directionality in a fuse used in an ac circuit is because of the cycle going to... and not fro. For what its worth,it sounds plausible.

There can be reasons why a cable has directionality (mostly having to do with how the shield is constructed; this has nothing to do with fuses). But this bit:  "the reason there is directionality in a fuse used in an ac circuit is because of the cycle going to... and not fro." - is a false statement (and is false because AC does indeed go "to and fro", if it does not, its called 'DC'). Therefore its not plausible that a fuse can be directional, and anyone telling you otherwise is trying to sell something and is hoping you are gullible enough to not see the fraud. 

To understand the fraud that is happening here, you first have to understand that in an AC circuit, the voltage drop across the component has to be the same in both directions. Otherwise one of two things will happen, both governed by Ohm's Law: either the component will heat up (as in the case of an electrolytic capacitor when reverse biased by half of the AC current flow; this will cause it to heat up and explode) or rectification will occur (as in the case of a power rectifier, which can conduct in one direction but not the other- this BTW is how AC is converted to DC). So if a fuse is directional (entertaining that impossibility for a moment) that means that it will have a resistance value of x in one direction (some fraction of an Ohm) and in the other direction the resistance will be x plus something more. The idea is of course ridiculous, as if this were the case, the additional voltage drop in the higher impedance direction would cause the fuse to heat up with eventual failure. This is Ohm's Law we're dealing with here- its a simple formula and can't be violated without creating a new branch of physics. So if anyone tells you that fuse direction make a difference, either they are grossly misinformed or just outright lying.

It really is that simple. 

Right my understanding is the reason the Monster wires are directional as indicated is because of the shield implementation.   That's pretty much the only reason that I have read of.   My MIT wires have no indicators and I can't say if it matters or not there.   Fuses are a different story.    Most high end audio fuse makers seem to leave a lot to the end listener's imagination.

The original monster cable, which came with arrows indicating the direction of current flow were actually unshielded cables. They had clear jackets so you could see the (unshielded) copper right through them. So you can’t use the excuse that the directionality is a shielding issue (only). Besides, many audiophile interconnects have had arrows on them for more than 20 years. They are unshielded cables, at least many if them are. This is not to say shielded designs need to be inserted in the right direction shielding wise, but unless the manufacturer was smart enough to maintain the directionality of the conductor it’s still going to be somewhat messed up. All wire is direction. Accept the inevitable.