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

how about a low power DC standard of, say, 48V with connectors rated at, say 10A?

David, you're 100% aligned with our thinking!  One initiative we're planning is to write a functional spec for exactly such a connector, for domestic portable appliances, and organise a competition for connector manufacturers to design their proposal for meeting the spec, make some prototypes on a 3D printer, and submit them to a panel of impartial experts to assess against a pre-defined set of criteria - practicality, robustness, low cost, ease of manufacture, etc.  We already have a draft spec.


When one defines a connector like this, it is also necessary to define a wiring code for the associated fixed wiring.  For 230VAC in this country, ring mains save on cabling by allowing 32A on the cable, and a 13A fuse to limit the current for each appliance.  Our thinking is that 48VDC should be a radial system with a 10A limit on each branch, even if the branch has several sockets - and no individual current limit for an appliance.  (Most of Europe wires its 230V sockets this way.)   Do you agree?


Another important question is whether we have a 2-wire or 3-wire system (with a protective earth).  Our thinking is that in the appliance both power wires must be galvanically isolated from any exposed metalwork, but not necessarily double-insulated.  (Note that many 12VDC appliances are not galvanically isolated - they have the exposed metalwork connected directly to the negative.)   A non-current-carrying PE conductor would only be used to connect exposed metalwork in wet environments where corrosion would otherwise be a potential problem.


Lastly, should it be positive-earth (like the telephone system), or negative-earth (like most vehicles), or have the mid-point earthed (detects any earth leakage from either power conductor like the London Underground, also best for radio interference, corrosion etc)?


We would be keen to hear your (and anyone else's) views on this!

how about a low power DC standard of, say, 48V with connectors rated at, say 10A?

David, you're 100% aligned with our thinking!  One initiative we're planning is to write a functional spec for exactly such a connector, for domestic portable appliances, and organise a competition for connector manufacturers to design their proposal for meeting the spec, make some prototypes on a 3D printer, and submit them to a panel of impartial experts to assess against a pre-defined set of criteria - practicality, robustness, low cost, ease of manufacture, etc.  We already have a draft spec.


When one defines a connector like this, it is also necessary to define a wiring code for the associated fixed wiring.  For 230VAC in this country, ring mains save on cabling by allowing 32A on the cable, and a 13A fuse to limit the current for each appliance.  Our thinking is that 48VDC should be a radial system with a 10A limit on each branch, even if the branch has several sockets - and no individual current limit for an appliance.  (Most of Europe wires its 230V sockets this way.)   Do you agree?


Another important question is whether we have a 2-wire or 3-wire system (with a protective earth).  Our thinking is that in the appliance both power wires must be galvanically isolated from any exposed metalwork, but not necessarily double-insulated.  (Note that many 12VDC appliances are not galvanically isolated - they have the exposed metalwork connected directly to the negative.)   A non-current-carrying PE conductor would only be used to connect exposed metalwork in wet environments where corrosion would otherwise be a potential problem.


Lastly, should it be positive-earth (like the telephone system), or negative-earth (like most vehicles), or have the mid-point earthed (detects any earth leakage from either power conductor like the London Underground, also best for radio interference, corrosion etc)?


We would be keen to hear your (and anyone else's) views on this!