Cable Calculations - terms, symbols, factors, values, protection
Cable calculation terms, symbols and data - ANSWERS
© K.Brown 2026.
CORRECT MATCHING ANSWERS SHOWN
© K.Brown 2026
Ib
In
It
Iz
Ca
Cg
Ci
Cf
Vd
correction factor = 1.00
correction factor = 0.725
11.5v
6.9v
20v
0.4 sec
5 sec
0.2 sec
BS3036
BS88
BSEN60898
MCCB
RCCB/RCBO
BS61008
BS61009
type 'S'
RCBO
300mS
not operate
30mA
Volts Drop = mV x design current x ?
? = mV x A x m
Vd = mV x ? x m
protective device rating/correction factors = ?
circuits installed in conduit/trunking
circuits installed on cable trays
circuits 'clipped direct' to a wall
max volts-drop for non-lighting circuit
max volts-drop for lighting circuit
Cc
Uo
(R1+R2)
Ze
Zs
design current (the current required by the load)
protective device rating
current value when factors have been applied
cable current-carrying capacity
factor for room temperature
factor for multiple circuits/condutors run together
factor for thermal insulation
factor for bs3036 fuse
voltage loss in a conductor
ambient temp = 30 degrees C
bs3036 fuses
max volts-drop for 230v non-lighting circuit
max volts-drop for 230v lighting circuit
max volts-drop for 400v circuit
max disconnection time for a TN system circuit below 32A
max disconnection time for a TN system circuit above 32A
max disconnection time for a TT system circuit below 32A
semi-enclosed fuse
HRC fuse
miniature circuit breaker
circuit breaker in its own enclosure
combined mcb and rcd
RCCB
RCBO
time-delayed RCD
combined rcd and mcb (with overload protection)
RCBO disconnection time at 100% its rating
RCD tested at x0.5 its rating
rating of RCD for additional protection
length
Vd
Amps
Tabulated current
Reference method B
Reference method F
Reference method C
5%
3%
Correction factor for circuits buried in the ground
Line to earth voltage
mΩ per metre
External Impedance
Total Impedance