How do we create or adapt infrastructure within homes or workplaces so that DC appliances can be adopted?

The 50V is safe thing is a convenient round number, not a matter of fact. - really it is shock current that matters, and wet vs dry  hands or shoes vs bare feet, or both, can make the difference between an bit of a tingle from 230V and yet the odd fatality from voltages as low as 28 - though the only deaths at 28V  I am aware of were army personnel already badly  injured, and being wet with lost blood probably contributed to the lower body resistance.

In regulation land it is a black/white limit, in engineering reality - and much like the other one at 1kV, it is a bit more grey.

The other thing against higher voltages at DC vs low frequency AC is that there is no natural extinction of arcs, so switch gear has to be rated for VA product, rather than just peak volts based on gaps and peak amps based on heating metal calculated  separately (the rate of growth of  volume of plasma  at the arc has to be less than the rate of increase of the volume between the contact)   (a demo video) This means that  DC switches must be bigger and more ‘snappy’ than their micro-gap AC counterpart for the same voltage . If you have played with an arc welder you will find that the length of arc you can hold is mostly current dependent, rather than voltage, once you have enough open circuit volts to strike reliably. (and yes you can do acceptable welding  with just 2 car batteries in series, but it is not very good for them and you need to be quick)  

For electrics in more developing places, I'd expect the double fault to danger principle that requires both a fuse and an earth to be widely ignored, and a more pragmatic approach to risk of single insulation. Certainly the South American shower wiring I have seen with twist and tape wiring does not seem to kill the locals, but it makes one of a western education feel quite nervous on first contact.

Mike

The 50V is safe thing is a convenient round number, not a matter of fact. - really it is shock current that matters, and wet vs dry  hands or shoes vs bare feet, or both, can make the difference between an bit of a tingle from 230V and yet the odd fatality from voltages as low as 28 - though the only deaths at 28V  I am aware of were army personnel already badly  injured, and being wet with lost blood probably contributed to the lower body resistance.

In regulation land it is a black/white limit, in engineering reality - and much like the other one at 1kV, it is a bit more grey.

The other thing against higher voltages at DC vs low frequency AC is that there is no natural extinction of arcs, so switch gear has to be rated for VA product, rather than just peak volts based on gaps and peak amps based on heating metal calculated  separately (the rate of growth of  volume of plasma  at the arc has to be less than the rate of increase of the volume between the contact)   (a demo video) This means that  DC switches must be bigger and more ‘snappy’ than their micro-gap AC counterpart for the same voltage . If you have played with an arc welder you will find that the length of arc you can hold is mostly current dependent, rather than voltage, once you have enough open circuit volts to strike reliably. (and yes you can do acceptable welding  with just 2 car batteries in series, but it is not very good for them and you need to be quick)  

For electrics in more developing places, I'd expect the double fault to danger principle that requires both a fuse and an earth to be widely ignored, and a more pragmatic approach to risk of single insulation. Certainly the South American shower wiring I have seen with twist and tape wiring does not seem to kill the locals, but it makes one of a western education feel quite nervous on first contact.

Mike