When wiring cables, do I need to put a metal hose from the galvanized pipe to the motor? Is there a relevant specification?

The need to add metal hose (or called snake skin tube). And galvanized pipe this end and the motor junction box this end should be added with metal hose supporting self-fixing fittings or hose fittings (or called ferrules), if there are waterproof or explosion-proof requirements, the joints need to be special waterproof or explosion-proof fittings.

In addition, GB 50169-2006 electrical installation engineering grounding construction and acceptance specification 3.2.9: shall not use the snake skin pipe, pipe insulation metal skin or metal network, low-voltage lighting network lead wire lead skin and cable metal sheathing for the grounding line. Snakeskin pipe ends should be self-fixing joints or hose joints, and both ends should be connected by soft copper wire.

This clause is marked in black font, meaning that this clause is a mandatory provision, so the hose must be spanned with a soft copper wire, otherwise, if it is strictly pursued, it is a violation of the current law.