A highly esoteric debate is emerging among technophiles lately about whether our houses should be supplied with direct current rather than alternating current, and it has generated an interesting sidebar debate; at Coney Island on January 4, 1903, did Thomas Edison electrocute a grumpy elephant named Topsy?

Edison was DC’s great believer and had been through a bruising battle with George Westinghouse ten years earlier when US authorities were choosing between it and AC to light their cities. AC could be transmitted over far longer distances while DC needed a power station in every suburb, but DC, according to Edison, was safer. Westinghouse won the battle when he underbid Edison to light the Chicago World’s Fair in 1893, but it didn’t stop Edison’s company recording the death of the unfortunate Topsy from 6600 volts of killer AC on film. It’s on YouTube.

For a performing elephant Topsy was a poor choice. She killed three men in three months and menaced police investigation teams. Clearly she had to go and her execution is still erroneously portrayed as part of the ‘Battle of the Currents’.

Electrocuting an elephant? Was Edison really so unpleasant? Research by Rutgers University suggests he may not have known about the execution, much less attended it, but there is no denying that his company filmed the incident and put his name on it.

Which brings us to the matter at hand; why DC? It still has its deterioration problems and with residual current devices and a century of development AC is now safe enough that any death by accidental electrocution usually makes the news and, if insulation is being laid at the time, helps bring down governments.

Actually we’re already well down the DC path. Tot up the number of devices running on DC at your place. First of all, everything with a battery. Not just your torch and the kids’ Brio locomotives, but your mobile phone, iPad, laptop, kindle, portable Bluetooth speaker, anything with a little box between it and the wall outlet. Many televisions and lots of home entertainment equipment have AC to DC converters inbuilt. DC is the reason your house phone still works in a blackout. Have you switched to LED lighting? That’s DC. So are Tesla Powerwalls.

Now think environment. Solar power is making the economies of clean, local generation far more attractive, indeed lots of houses now power themselves by solar which is inherently DC, using inverters to convert to 240 volts AC. If your solar system is one of these you’re likely suffering a loss of 20 per cent of power at the inverter and, if you’re plugging in a pack that converts this AC back to DC again to power your DC stuff you’re losing another 20 per cent or so there. A switch to DC would avoid all this wastage.

Estimates vary but it is argued by bodies like the EMerge alliance in the United States (emergealliance.org) that up to 20 per cent of power consumed in the average home is DC, the major exceptions being in kitchens and laundries.

Fair enough, but conversion is a can of worms. What voltage should be run? Some current equipment needs 12 volts, some nine or five, USBs take three. Fussy hi fi equipment needs more and air conditioners, heaters, stoves et al lots more. Do we have multiple voltages with outlets that detect what’s needed?

The more one delves into this the more complex it becomes which is why change, if it’s ever made, won’t come soon. Bad news for elephants, the upside is that the debate becomes continually more fascinating.

Published October 2016

 

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