From the desk of Jan Hommel, Museum Director:

Q: Which president was the first to have electricity in the White House?

A: Benjamin Harrison. Electricity came to the White House as part of a plan for wiring the State, War & Navy Building next door. The Edison Company installed a generator for both buildings and wires were strung across the White House lawn and under the conservatory. Wires were buried inside the plaster walls of the rooms and round switches were installed for turning the current on and off. President and Mrs. Harrison were so fearful of being shocked that they refused to touch the switches and called on the domestic staff to operate them. (Smithsonian Presidential Trivia)