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

Peter Bernard Ladkin: 
 

Christopher Moller: 
 

(A reply to Peter Ladkin)

It is noteworthy that there are far more international standards relating to electrocution (which has fortunately become rarer since the introduction of RCDs), than to prevention of fire.  

That has to do with history, I think. In Germany, the electrotechnical engineering professional society VDE was founded in 1893 and that same year the electrical-safety low voltage standard VDE 0100 was published. 

I don't actually definitively know if electrocution was the main concern then, or electrical fires, or both.

It is a bit different in the UK, since the forerunner of the BSI was founded separately from the STE/STEE/IEE and IIE. 

The original version of BS7671, The Wiring Regulations was "Rules and Regulations for the Prevention of Fire Risks arising from Electric Lighting."

Hi Peter you make a very good point about how fragile our resilience is now that we are a digatalised society. Part of me wants the EU to turn off the nuclear power and gas we have taken for granted to wake us up a bit . . . so that we can innovate some future-primitive resilience ahead of the whip-crack of climate change.

 

Peter Bernard Ladkin: 
 

Great set of questions. 

There is of course a difference between what people need (and what they say they need and what others say they need) and what they want.

What people everywhere need is (a) adequate and safe water; (b) adequately nutritious and safe food; c) a certain level of primary health care. Electricity is an energy source. The question is how energy can contribute to (a), (b) and c) (I don't write the left bracket because the phrase is turned into a copyright sign. An partial answer is that (b) and c) do depend on local cooling below ambient temperature, and this is currently only achievable through using energy. That may well be true of (a) also; I don't know. 

But (b) also depends upon social interactions that are facilitated through communication and indeed commerce. Commerce is now possible through the introduction of cell-phone payment systems; and through the communication which makes remote negotiation with remote suppliers possible. If it takes two days to reach you, you can only get enough safe meat and veg if you can negotiate it remotely and have it delivered once a week, say, in a truck. The truck uses energy, and some of that can be used for cooling; but when it gets to you you need to cool it for the next week until the next shipment arrives. 

Such distribution systems are likely the only way people can avoid the pervasive use of bushmeat and thereby exposure to zoonotic disease such as Ebola, and whatever is coming down the pike ahead of us.

But then there is the question of the resilience of these systems (raised by others). Roger Kemp ran a workshop for the RAEng on “Living Without Electricity” (available from their WWW site), about the Lancaster Christmas outage a few years ago. He pointed out that we were much more resilient concerning such events 50 years ago. You lost lighting, and TV, but everything else worked. But now, everything seems to depend on a reliable electricity supply. 

Gotta go. But glad to be part of this conversation

Allan Burns: Funny, we the forum were just having a chat about this (DC lighting breakaway) and it reminded me of your post. Splitting the board is doable. Swapping out luminaires for DC compatible is more of a shopping exercise than an engineering challenge. The cost of a good, stable safe ELVDC storage system might be a bit high for most.

What is an engineering challenge is how you handle switching - the DC arcing in the old switches is liable to be a big fire-safety issue!

We's welcome your thoughts Andy . . . 
 

Andy C you are talking my language! I'm flat out at the moment but will be posting on this subject soon . . .

 

Andy C: 
 

I was recently reading a ‘home handyman’ book, basically a DIY book from 1931. It was interesting reading about the electricity supplies provided to houses where they had in effect two incoming mains supplies and meters, one for lighting charged at 1d per kWh and the other for power charged at 8d per kWh (1931 prices, roughly £2 today). Also explains why my grandparents had one of those adapters which plugged into a light socket which you could run an iron from.

Would it be an idea to consider a similar approach today to domestic wiring in new properties? Have totally separate lighting and power supplies with a low voltage DC system for lighting and electronic appliances (phones, laptops etc) and a mains AC system for heavier loads such as heating, washing machines, A/C etc. It would be fairly simple to have the DC side run from solar panels/wind turbines/whatever with battery backup and possibly a mains charger for those few times when there is insufficient input to keep up with demand.

To some extent it would also be fairly simple to convert/upgrade the existing housing stock, at least with regard to LV lighting circuits and maybe adding some LV outlets for phones etc, and would give some protection against being left in the dark due to failures of the grid or too many people plugging in their electric cars to charge!