A
atto2007
Hi guys,
struggling to work this question out and don't seem to be getting a correct answer no matter what cable conductor size i use.
Q. A 230V 14kW domestic electrical cooker, installed in a house is to be supplied by a 15m run of PVC insulated and sheathed cable, clipped to a surface. The cooker control unit has no integral 13A socket. The circuit is to be protected by a BS3036 fuse and the value of external impedance is 0.85 ohms. Calculate the minimum size cable that can be used for this circuit to comply with shock protection.
Ib = 14/230*1000 = 60.87A
In = 100A therefore max Zs = 0.53 ohms. ( i think)
Zs = Ze + [(R1+R2)*mf*L]/1000
Zs = 0.85 + [(1.83)*15] / 1000
Zs = 0.88 ohms ( too high)
using 50mm cable Zs = 0.85 + [0.387*15] / 1000
Zs = 0.86 ohms (still too high)
Feel im missing something obvious.
struggling to work this question out and don't seem to be getting a correct answer no matter what cable conductor size i use.
Q. A 230V 14kW domestic electrical cooker, installed in a house is to be supplied by a 15m run of PVC insulated and sheathed cable, clipped to a surface. The cooker control unit has no integral 13A socket. The circuit is to be protected by a BS3036 fuse and the value of external impedance is 0.85 ohms. Calculate the minimum size cable that can be used for this circuit to comply with shock protection.
Ib = 14/230*1000 = 60.87A
In = 100A therefore max Zs = 0.53 ohms. ( i think)
Zs = Ze + [(R1+R2)*mf*L]/1000
Zs = 0.85 + [(1.83)*15] / 1000
Zs = 0.88 ohms ( too high)
using 50mm cable Zs = 0.85 + [0.387*15] / 1000
Zs = 0.86 ohms (still too high)
Feel im missing something obvious.