I was recently reading Angela's Ashes, and I found it interesting that electrical lighting was only for the rich. When and how did electrical wiring become popular?
Ok, I hadn't read Angela's Ashes, and had to look up a summary of it. It looks like you are referring to the time in Ireland?
If so, I'm going to have to bow out, because my knowledge of the electrification of Ireland is non existent. In the United States, by the 1930's, electricity was far from a luxury for "the rich". Only the absolute poorest or rural folk would lack it. You may find this thread of some interest in regards to rural electrification in the United States
It was in the late 1890's originally it was for wealthy people who had the money to convert. Edison actually came up with many of the devices used along with other early inventors. In some homes the pipes that routed gas through the house were used to pull wires and an electric box was added at the end to support an electric light. Some older homes still have this original wiring in place.