Volt drop and Cable length from Prospective Short Circuit Current Calculator

Measured PSCC  
at source amps
i.e. at consumer
unit. 
Measured PSCC
at destination amps
i.e. at furthest point
or mid position on a ring. 
Size of
Live conductors  
Ring Main   Ambient
temperature
°C
Nomial volts Max permitted
operating temp tp
Rating factor
for grouping Cg
Rating factor for
ambient temperature Ca  
Design current
for circuit Ib
Suggest

Tabulated  
current-carrying  
capacity of  
a cable It  
Orignal  
mV/A/m  
Corrected  
mV/A/m  
Correction  
factor Ct  
Cable  
length  
meters  
Volt  
drop  
Impedance of local  
Live conductors  
Ω  
  Total=

Click on Calculate to get results. The default settings are for a ring main at maximum length with a 32A B type MCB/RCBO with a TN-C-S supply with a ELI of 0.35Ω the idea being to identify when parameters have been exceeded when doing an EICR. In this version no account has been made of the earth, it is assumed protected by RCD so is not a problem with normal installation. With the Design current for circuit (Ib) once the calculate button is hit a suggestion in made. It is assumed with ring the 20 amp plus half remainder is used but with radial it is the total of the MCB fitted. The suggest figure is what one would expect, but with a single appliance this may be much lower.
Note:- Impedance of local live conductors is the impedance of the circuit consumer unit to destination. Total is given as this will be reading taken with a loop impedance meter. With a TN-C-S supply this will be the difference will be Ze.
It is assumed the PSCC will be measured line – neutral.

Installation method 100 information used for current carrying capacity. This program has been converted from an old Excel program and there may be errors. Since installation method 100 is use there may be cases where it does not give true results.