Limiting voltage drop is not an NEC requirement. VD is mentioned in an FPN which is not enforceable.
True the NEC does not enforce VD...but the manufactures of the electrical devices do have limitations of operation, performance and efficiency concerning VD.
I'm adding this section because I think gideonr posted as I was writting this reply.
About Voltage Drop and Ohm's Law. Ohm's law works great with DC systems but falls short on AC systems with power factors and alternating current sinusoid waves.
[This message has been edited by DiverDan (edited 10-30-2005).]