> What about stepping down to 24VAC or 48v if you have such 
> transformers
> and stepping up to 230V outside.
> Isn't there a voltage below which you can do what you like, maybe 
> 48VDC.
> Yours is a low current requirement IIRC.

It's called "ELV" = Extra Low Voltage.
Value varies with administrations.
AFAIR often 50 VDC and 32 VAC but giggoloing for ELV should tell you.

I was thinking only yesterday of just the opposite :-) - using an HV 
distribution system to reduce conductor sizes for power distribution 
around residential sections. I suspect the regulatory requirements 
would kill that idea. Shame though: power loss decreases approximately 
proportionately to the step up ratio of the system, which is why EHT 
transmission lines exist. Driving a 12v 100 Watt halogen at the far 
end of your garden with a drop of say 2 volts max and a 50 metre run 
requires about 0.25 ohm loop resistance. Dunno off the cuff what that 
is in wire gauge but its not nice. (8 ohms mile = 200lb per mile in ye 
olde telecom parlance). Or Area mm^2 = Length/60/resistance = 
50/60/.125 = 6.5 mm^2. (0.125r as half loop)
That's "rather thick". Take that up to 230V feed and it's about 
0.3mm^2. Take it to 1000V and it's about 0.08 mm^2.
Take .. bzzzzzt!!! ...


        Russell



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