I am located about 50 miles from San Francisco but have never done any work in the city. I have heard they have some interesting amendments but haven't had a chance to see them until now. Thanks Nick! There are some local communities that require all wiring to be in raceways but since SF isn't on of them I'm not sure why they house you saw was being done this way.
I listed a few of the amendments below.
215-8. Means of Identifying Conductor with Higher Voltage to Ground. On a four-wire, delta-connected secondary where the midpoint of one phase winding is grounded to supply lighting and similar loads, the phase conductor having the higher voltage to ground shall be identified by an outer finish that is purple in color or by tagging or other effective means.
347-2 Rigid Nonmetallic Conduit can not be used where exposed.
351-23 Liquidtight Flexible Nonmetallic Conduit can not be used for circuits exceeding 50 volts.
339-3 Type UF Cable can not be used for circuits exceeding 50 volts.
Curt
