Circuit length and voltage drop

[MALContracting]

Hi,

I'm currently doing my assignment for 2357 and was just making sure I'm calculating the cable length for the lighting circuits right. As depending which way you do it, it alters the voltage drop a bit.

On the drawings I've looped in and out at the switches all the way to the final light switch with a S/W+N going to each light from the switches. For example one switch switches about 8 LED fluorescent batten lights.

When calculating the circuit length, would you measure from the DB board to the first light switch including the loop in and out onto the last light switch then onto the last light fitting as to where you would measure your Zs?

Or do I have to measure from the DB, each loop in and out from the switch to the last one, plus the S/W+N to all the light fittings?

I've searched the forum and people have mentioned that obviously the voltage drop gets less between each lighting fitting as the radial goes on but we've never been taught anything about this in college so I'm guessing we calculate it as one circuit.

 

[telectrix]

for volt drop on the circuit, say 10 lights, you calculate the VD to the first light at FLC. then the 2nd light at FLC -10%, at 3rd light FLC -20% and so on.