Wires Physically Move When Breaker is Enabled
Is the disposal starting? If the disposal is stuck it could be drawing locked rotor current many times the circuit breaker rating causing the wires to jump even if it is starting a motor normally draws 3-5× its FLA or full load amperage for a fully functional motor. This combined with possibly a longer than normal length distance to the first staple it could be somewhat normal. If you hacer ever watch welding leads jump my big welder when on high the leads may jump a couple of inches with a heavy or thick rod. To further explain your home circuit breakers are inverse time they will hold 10x there rating for a very short time 150 -200 amps in that 14 or 12 awg wire will cause to jump. Hope this helps.