Much better method than following the smoke!
An even better method is to calculate the wire size needed...
With plenty of safety factor, as a rule, and 24h/7d application, ie continuously for DC applications, 50 degree cable temp:
0.75mm2 = 6 amps,
1.5mm2 = 10 amps,
2.5mm2 = 16 amps,
4mm2 = 25 amps
You can downsize if you know for sure duty time (heating) vs rest time (cooling).
But you will need to increase if wires are near other heating devices. Most cables are rated for 70 degrees C continuous operation, some others at 90 degrees C.
Never use a fuse or breaker accordingly to the load, but always use a fuse or a breaker accordingly to the wire size...
Heat and smoke always is the result of too small a wire for the protection used... The load just takes what it needs.
DC is a strange animal that prevents the wires from cooling and reversing as on AC circuits, so always make sure your connections are clean and tightened as required. Not tight enough is no good for sure, but too tight is no good either... Proper crimp with ratchet tool and solder as well is top for DC...
Patrick