In the cellar beneath a nearby stable, a steam engine, boiler and electrical generators clanked and roared away, writes historian Jill Jones in her 2004 book Empires of Light . Connected to the house via underground cables, these were manned by an expert engineer, who started duty at 3pm and finished at 11pm. Sometimes, when the family forgot to watch the clock, they would be suddenly plunged into darkness at this point, Herbert Satterlee, Morgan's son-in-law, later wrote .

"New York City was the first place where commercial electricity was built and sold at scale in the US," says Robert Lifset, associate professor of history at the University of Oklahoma who specialises in the energy history of the US – although there were "quite a few" controversies that took time to be resolved, he adds.

But the city was already eager for a better alternative to gas, says Harold Wallace, curator of the electricity collections at the Smithsonian's National Museum of American History in Washington DC. "Politicians are complaining about companies that aren't maintaining their systems well, users are complaining about odours and impure gases that are being used, and there's a lot of calls for something to replace, or at least provide competition for, the gas systems," he says.

An enthusiastic group of engineers and inventors centred in New York were eyeing this opportunity. The sheer size and density of New York, already a very populous city, provided an incredibly handy backdrop for field tests on electricity networks. "Being able to test at scale in New York City was really advantageous," says Wallace. "[Edison and his team] figure if they can make the system work in New York, then they should be able to scale it down, basically, and make it work in other markets."

Edison was adamant that he was creating a lighting system, not a general overall electrical system, which evolved later, says Wallace. But he did want to make sure it was competitive with gas, he adds, coming up with a figure of a 16-candlepower output, so as to top the 15-candlepower he had surveyed as the average light produced by a gas jet in New York City.

While working for Edison, the charismatic Serbian-American scientist Nikola Tesla had proposed using a different electricity system based on alternating current (AC). "With alternating current, you can transmit the power over much further distances," says Wallace. "You can have a few much larger power stations." AC could be more easily converted between high and low voltages using transformers, which only work on AC electricity.

But Edison dismissed the proposal, arguing his more established DC was safer than the experimental AC which had "no future to it". Tesla soon quit and teamed up with railway entrepreneur George Westinghouse, who was also interested in the ability of AC generators to transport electricity over long distances.

The war of the currents was hugely important in determining the future of electrical systems, according to Lifset. "The switch to AC power allowed for the use of larger power plants located further away from their customers," he says. "This served as the foundation for the industry's emerging business model. It's what allowed electricity to become cheap and was a significant factor in the spread of electrification."

The insatiable rise of these technologies mean we are actually using growing proportion of DC in electricity consumption, while some of world's longest transmission lines now use high-voltage DC electricity. Some researchers argue that this increases the case for direct DC power to end users over a century after AC won out.

Edison, Westinghouse and Tesla had proven that electricity was a game changer for lighting. But it wasn't the end for gas. "The gas industry went back, they upgraded their systems, they came up with new refinements so they could put out cleaner gas that didn't have the smell or create quite as much soot," says Wallace. "They also came up with new applications." The industry began promoting gas for cooking, heating and even refrigerators .

Electricity also soon expanded to more than lighting. "Very quickly within the 1880s other applications occur," says Wallace, including electric fans and irons as well as larger items like refrigerators and stoves. "[Electric refrigerators and stoves] take quite a bit more of an investment, so most people couldn't afford them early on, but they could afford an electric fan, or especially an electric iron was marketed very heavily early on."

Since most tenements or apartment homes had only a single light bulb socket hanging in the middle of the room, these early irons and fans would have light bulb bases that could be attached to an adapter and plugged into this socket, says Wallace. "It was not until the late 1890s, into the early 1900s, when what they called convenience outlets, [what] we think of as wall sockets today, first really started coming on the market."