level 3 unit 303 question help !

[jules27]

Hello there people ,

Got a level 3 unit 303 question i m struggling with , any hellp please ! An earth loop impedance test on a socket supplied via a c type breaker measures a value which is just over the permitted value. State two methods which may be used to overcome this problem, assuming the circuit and wiring are sound.

exam on tuesday !
cant work it out.

cheers

 

[T&Earth]

Hi Jules

Change the Type C to Type B or fit RCBO or increase CSA of cable

 

[jules27]

Can you also use the rule of thumb and take 80% of Zs as the value given is st max operating temp?
cheers for the help

 

[pushrod]

I think the other answer they are after, in addition to the C type to B type breaker, is to reduce the size of the breaker if the design current allows eg a 20A to a 16A. The smaller the breaker the larger the Zs.
Although increasing the csa of the conductors would work it is not really an option when the circuit has already been installed. Had the very same question in my 303