Our Utility provider needed to do some switching of our power feed yesterday and returned it to normal today.  At approximately 1545 PST 29Nov2016 DOE contractor changed our feed from one buss to another at the substation for work that needed to be done on other circuits in the substation.  At approximately 1350 PST 30Nov2016 they restored our circuit to the normal feed.   Fortunately with the new switch in the system we did not see this work.  The IFO remain locked and everything seemed fine.  A cursory look at Line monitors and Magnetometers did not reveal any anomalies.  If any of our PEM monitors did see an event at this time please let us know as this is useful feedback.