regs question

[soulman]

hi can anyone tell me what r x z stand for in volt drop tables in the regs cheers.

 

[NozSpark]

That's for the type of load

Resistive, reactive or capacitive

 

[soulman]

thanks mate! that was quick

 

[moose man]

HI soulman

Colume z is the impedance value r and x are the resistive and reactive

when calculating the volt drop on a three phase cable above 16mm use the impedance value

if your doing additional calcs based on operating temp (6.1 on page 258 BS 7671 you use

r and x values to get a different value of z this allows you to get a better value of volt drop

if your operating current allows

 

[septiclecky]

It's used for calculating large cable sizes as the reactance impedence of the small cables is deemed to be neglible that is why you are only given r.

 

[soulman]

cheers lads!