can you check my volt drop

[beaver74]

hi all
got a sud main to price 45A 27m

45A x 27m x 4.4mV/A/M for 10mm divid 1000

VD 5.34V

now some of the circuits on submain are lighting mav VD 6.9V leaving only 1.56V for the lighting circuit.

6A x 20m x 44mV/A/M for 1.0 divid by 1000

VD 5.28

now am i right to say this sub main will not comply as the final cicuit VD would be in access ov 3% for the lighting circuit

cheers in advance

 

[andyb]

Beaver

Try 1.5 for the lighting circuit, then keep the circuit lengths down and use 3 amp mcb,
Or use 16mm cable for your sub main and 3 amp lighting circuits will see you home even with 20m lighting circuits.

 

[Chr!s]

hi all
got a sud main to price 45A 27m

45A x 27m x 4.4mV/A/M for 10mm divid 1000

VD 5.34V

now some of the circuits on submain are lighting mav VD 6.9V leaving only 1.56V for the lighting circuit.

6A x 20m x 44mV/A/M for 1.0 divid by 1000

VD 5.28

now am i right to say this sub main will not comply as the final cicuit VD would be in access ov 3% for the lighting circuit

cheers in advance

Are there any factors to be applied, in other words whats the it.

if it = 64 amps, i get a volt drop of 4.98, that would leave a couple of volts for final circuit(lighting)

 

[pushrod]

A 6 amp breaker will protect your lighting circuit but how many lighting points are there?

6Amps is not your design current unless you have 13 lighting points and you are allowing for 100W per point. I am guessing maybe 300 or even 400W giving 1.7A is probs still generous and will give you an overall volt drop of less than 3% and you would get even more leeway if needed by going up to 1.5²mm