E
electric-tec
Hi All
Just thought id post this and see what the verdict is,had a couple of emails from good guys telling me ther thoughts.
Senario.. A small workshop with a canteen and toilets are wired in 70 deg single core thermoplastic cables enclosed in tubing, the light in the toilet are wired from a photcell and the fittings are flourecent, the Ze is 0.3ohms and pfc 16kA.
Q, A radial circuit fedding a heater in th office is fed from a 40A beaker the value of the combined conductors are 0.23ohms, calculate the volts drop for the circuit,
i answered. (ri+rn) x Ib = 0.23 x 40 = 9.2v
then had a brainstorm from doing previous stuff in class of adding a correction factor of 1.2 then with 5 min to go decided to change 1.2 to 1.04 as in GN3 it states 1.04 for cables that are single 70deg not enclosed or bunched or embedded so answer became 9.56v still under then after exam looked at GN3 only to find i used the 1.04 for the mv/m for cable factoring for bonding and not temperature,
So when my papers marked he will see i had 1.2 then changed to 1.04 showed all equations and calculated the percentage.
QUESTION IS do you think i will score anything or nothing was a 15 mark question ?
Just thought id post this and see what the verdict is,had a couple of emails from good guys telling me ther thoughts.
Senario.. A small workshop with a canteen and toilets are wired in 70 deg single core thermoplastic cables enclosed in tubing, the light in the toilet are wired from a photcell and the fittings are flourecent, the Ze is 0.3ohms and pfc 16kA.
Q, A radial circuit fedding a heater in th office is fed from a 40A beaker the value of the combined conductors are 0.23ohms, calculate the volts drop for the circuit,
i answered. (ri+rn) x Ib = 0.23 x 40 = 9.2v
then had a brainstorm from doing previous stuff in class of adding a correction factor of 1.2 then with 5 min to go decided to change 1.2 to 1.04 as in GN3 it states 1.04 for cables that are single 70deg not enclosed or bunched or embedded so answer became 9.56v still under then after exam looked at GN3 only to find i used the 1.04 for the mv/m for cable factoring for bonding and not temperature,
So when my papers marked he will see i had 1.2 then changed to 1.04 showed all equations and calculated the percentage.
QUESTION IS do you think i will score anything or nothing was a 15 mark question ?
