When Agent May Delegate Powers

An agent, unless specially forbidden by the principal to do so, can delegate the agent's powers to another person in any of the following cases and in no others: (1) when the act to be done is purely mechanical; (2) when the agent cannot and the subagent can lawfully perform the act; (3) when it is the usage of the place to delegate the powers; or (4) when the delegation is specially authorized by the principal.