Is there an optimal length for a power cable to a distribution block? Im bidding a 5m long and I’m wondering if 2m or 3m would not be better (don’t need 5m long).
You might ask if there is an optimum length of the mains cable from your consumer unit to the mains outlet for the hifi…
If you do not need 5m, do not do it. Make only as long as you need, but do not go less than 1.5m.
Oddly enough there is. But it’s complex. Discussed this with my electrician recently and the first variable is the nominal voltage coming into the home. If this is on the undervoltage side, shorter mains to the CU of thicker conductors will prevent further voltage dropoff. A long run of bog standard thickness (i.e. thin) will result in a noticeable voltage drop. So ideally you want the correct voltage, with short runs of low resistance thick wiring. The caveat being of course, the length is going to be as long as it needs to be so in reality you can only control the thickness. But while thickness can help with loss, thin conductors are not an acceptable way of compensating for over voltage.
It’s generally only a consideration in commercial installations where even a modest 20A circuit might have significant distance back to the breaker.
As for the OPs question… don’t worry about it. If you need a 5m mains cable, fine. Just get one with thick conductors.
Why not shorter than 1.5m?
Of course sorter could be used, no issues. Just some time ago made several test with replacing stock mains cables of equipment with better ones. Given results shown that cable shorter than 1.5 gives inferior sound quality and increase length further brings nothing. Since that time if need an extension use 1.5+