What would a safe robot look like?

[DonRotolo]

This is difficult because the topic is very broad. Assuming we mean 'best practices' here.

Insulation on the wire needs to be undamaged and applied by the manufacturer, in the proper color for the application. Ordinary PVC is acceptable in most cases, heat is the greatest issue that may require better insulation materials.

The wire insulation must be protected from damage, particularly chafing and rubbing - best practice is to cover both the wire with a formed insulator (not tape, but tubing, mesh sleeve, conduit, etc) and the chafe point with a wear-resistant cushioning material (e.g. felt tape, velcro loop, softer plastics, leather, cardboard, etc.).

Additional protection against damage is provided by bundling wires together neatly (with a clean lay) and fastening the wire or wire bundle (using zip ties, tape, etc) to rigid supports. Bundles large enough to be rigid require less frequent but stronger fastening.

Electrical tape provides both mechanical and electrical insulation. Tape must be at least three layers thick, with edges overlapped at least 1/3, to offer reasonable insulation properties. Good practice is to wrap tape with a 50% overlap (total is 2 thicknesses) and then a second layer in the opposite direction with 1/3 overlap.

Wire, even stranded wire, should be protected from bending to the extent possible. When wires must flex in their function, maintain as large a bend radius as possible. Flexing wires must not be bundled, or if they are then very loosely. Best practice is to end all binding just past the fixed end supports, enclosing the unbundled wires in a flexible covering large enough to allow the wires to move freely within. Highly-flexing wires should use finer stranding. Solid wire cannot be permitted to flex at all.

And that really only scratches the surface.