Volt drop in the real world

[TJC1]

Has anyone ever had a volt drop issue?

Just for fun.......... yes i said fun, i cant believe i would be saying that in my mid 20s

But i did a calc for a radial circuit in in swa

B32 mcb
4.0mm 3core swa
35m run

(mV/A/m)

So...... 11X32X30/1000 = 10.56

Way over the 5% in table 4Ab

Am i missing something? Would the design current me lower as there is no way the circuit would pull 32a

 

[EricMark]

One of the dangers of a building site is the impedance of cables plugged into yellow bricks. With proper transformers there is no problem as the MCB's are fitted to the output, but the yellow brick often has a 10 or 12 amp overload on the incomer only, so at 55 volt to earth 10 x 230 = 2300 VA / 55 = 42 amp, and 1.5 mm yellow flex will not take 42 amp for long. With a single cable the resistance of the cable is low enough that is a scaffold pole falls and causes a line - earth fault more than 42 amp flows so the trip operates, but once you start plugging cables into cables you can't get the 42 amp needed to trip the overload.

I personally think the dangers of fire exceed the danger from electric shocks and a risk assessment would show better to use 230 volt now nearly every supply is RCD protected, so on a site not large enough for a proper 110 volt supply using 230 volt is safer.

I can't see how the yellow bricks comply, but it seems they are still used.