> I've opened "large" cables to find tiny 28awg wire inside and a very thick jacket.
In a way, this is actually fine too — the conductor itself can be higher-resistance, as long as there's enough shielding to prevent the heat the conductor puts out from setting anything on fire. (Basically, following the same rules for sheath thickness as in-wall cabling uses.)
The only real practical difference, for most people, will be that anything electrically connected to the "thick sheath, thin conductor" cable, will get very hot. (And also, if you use such a cable to connect a device to a portable battery bank, you'll find you get your battery bankk will run dry sooner than expected, since your cable is acting as an additional load.)
In a way, this is actually fine too — the conductor itself can be higher-resistance, as long as there's enough shielding to prevent the heat the conductor puts out from setting anything on fire. (Basically, following the same rules for sheath thickness as in-wall cabling uses.)
The only real practical difference, for most people, will be that anything electrically connected to the "thick sheath, thin conductor" cable, will get very hot. (And also, if you use such a cable to connect a device to a portable battery bank, you'll find you get your battery bankk will run dry sooner than expected, since your cable is acting as an additional load.)