Technician A says twisted/shielded wire carries low current, and repairs to the wire must not increase the resistance of the circuit. Technician B says twisted/shielded wire carries high current, and any repairs must not increase the resistance of the circuit. Who is correct?

None of the them has a complete answer.

Explanation:

The current in a wire is a function of the conduction element geometry inside the cable, given by the resistance and the conduction area. So saying twisted/shield, is not giving us any information about the current rating of the wire.

Repairs to the wire may affect the area of the conductor, reducing the effective surface of conduction. But a well-executed repairing must made an insignificant change in the resistance. So it's not a definitive concept.

A twisted/shield wire is generally used for signal transport, as it's configured to reduce the noise in the data transmission.