While the answer to this question is obvious today, 130 years ago it was not so clear. Around your home, you have dozens of electronic devices that use either AC or DC - or more likely - a combination of both. That makes the question an example of a false dichotomy.
However, it became the centre of a savage battle between the two heavyweights in the emerging arena of electricity systems. In one corner was the Edison Electric Light Company, who'd based their business on delivering DC power.
In the other corner was the entrepreneur and engineer George Westinghouse who, in 1886, began construction of an AC power network.
Thus began one of the nastiest episodes in the history of technology.
Thomas Edison had pitched his investment into selling large-scale, low-voltage DC supply and indoor incandescent lighting.
That put him in direct competition with George Westinghouse's AC systems that used a high voltage transmission with step-down transformers for indoor lighting.
Westinghouse's solution offered a couple of key advantages. One was that it used more efficient, large central generating stations. The other is that transmission losses are significantly reduced over high voltage AC lines over longer distances*.
In the late 1880s, safety standards were poor, as were attitudes. Electricity companies took a casual approach, resulting in several highly publicised fatalities.
In April 1888, a 15-year-old New York boy was killed by a broken telegraph alternating current line and, two weeks later, a clerk was killed. In May that year, a linesman died when cutting an AC line.
These incidents sparked a media frenzy. An 1890 New York Times headline blazed: "Again the fatal wires; dreadful death..."
In the US, the engineer Harold Brown began a crusade against AC. Aiming to prove that AC is more dangerous, he performed a series of grisly experiments on stray dogs to compare the effects of direct versus alternating current.
In a public demonstration, he subjected a dog to shocks of direct current of up to 1000 volts. The audience shouted for him to stop and many walked out. And yet he continued, with a second demonstration soon after.
In Australia, the first recorded electrocution was in Richmond, Victoria, on December 27, 1890, and in contrast to the US stories, the fatality occurred with DC electricity.
The Sydney Mail wrote that "circumstances point to the fact that the deceased acted with recklessness" when an engineer named Pattison was killed while working on a dynamo.
This shows that, under the right circumstances, both AC and DC can be lethal. However, it is true that AC at the same voltage (50Hz frequency in Australia) is more dangerous than DC.
* This situation has changed somewhat with the introduction of high-voltage direct current (HVDC) transmission.
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