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.
what ive tried so far:
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.
what ive tried so far:
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.
