Well, a 'spur' rated at 32A requires 6mm2 cable. You could calculate a voltage drop along that based on resistance data. There is AFAIK no limit on length aside from practical limitations ! I don't know how the incoming feed from the electric company to the breaker box might drop with load though.
Graham
In the US, it's no less than 5% drop from the source to the load at full load.. conductor must be rated to supply a min of 95%.
for example, 10 awg = 0.999/M or 3.28/kg ohms
of course, all conductors are based from copper, copper being 100% of the scale. All others are based from that. etc..
I haven't looked it up properly but in the design of fixed installations you are not supposed to have more than a 4% voltage drop from the point of supply. So whilst 6mm cable will easily carry >32A, once you go over a certain length you would need to go up to 10mm to comply with the regs.
Thanks. Then from my calculations the maximum legal drop for any installation should be 13.6% from 240v - 207v and a bit, not including your own power distro.
Gareth.
Um, actually I think that's a bit innacurate as the 4% will be calculated for the power loss at 240v or even 254v? Close enough though.
Gareth.
Hah ! 230V -10%. That's what I test kit at when doing low voltage dropout tests.
Graham
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