| A |
ampere - unit of electric current |
| BC |
bayonet cap |
| Ca |
ambient temperature correction factor |
| CENELEC |
European Committee for Electrotechnical
Standardisation |
| Cg |
cable grouping correction factor |
| Ci |
thermal insulation correction factor |
| Ct |
correction factor for the conductor
operating temperature |
| CNE |
combined neutral and earth |
| cos 0 |
power factor (sinusoidal systems) |
| CPC |
circuit protective conductor |
| c.s.a |
cross-sectional area |
| De |
overall cable diameter |
| ECA |
Electrical Contractors Association |
| EEBAD |
earthed equipotential bonding &
automatic disconnection |
| ELCB |
earth leakage circuit breaker |
| ELV |
extra-low voltage |
| EMC |
electro-magnetic compatibility |
| e.m.f. |
electro-motive force |
| EMI |
electro-magnetic interference |
| ES |
edison screw |
| f |
frequency |
| FELV |
functional extra-low voltage |
| GN |
guidance note |
| HBC |
high breaking capacity (fuse) |
| HRC |
high rupturing capacity (fuse) |
| Hz |
Hertz - unit of frequency |
| I |
symbol
for electric current |
| I2 |
operating current (fuse or circuit
breaker) |
| Ia |
current to operate protective device |
| Ib |
design current |
| Id |
fault current |
| IEC |
International Electrotechnical
Commission |
| IEE |
Institution of Electrical Engineers |
| In |
current setting of protective device |
| It |
tabulated current |
| Iz |
current carrying capacity |
| IT |
earthing system (see 5.2.6) |
| k |
kilo - one thousand times |
| kV |
kilovolt (1000 V) |
| L1,L2,L3 |
lines of three-phase system |
| m |
metre |
| m |
milli - one thousandth part of |
| M |
meg or mega - one million times |
| mA |
milliampere |
| MCB |
miniature circuit breaker |
| MCCB |
moulded case circuit breaker |
| MD |
maximum demand |
| m.i. |
mineral-insulated |
| NICEIC |
National Inspection Council for Electrical
Installation Contracting |
| p.d. |
potential difference |
| PELV |
protective extra-low voltage |
| PEN |
combined protective and neutral |
| PME |
protective multiple earthing |
| PIR |
passive infra-red detector |
| PSC |
prospective short-circuit current |
| p.v.c. |
poly-vinyl chloride |
| R |
resistance (electrical) |
| R |
resistance of supplementary bonding
conductor |
| Ra |
the total resistance of the earth electrode
and the protective conductor onnecting it
to exposed conductive parts |
| Rp |
resistance of the human body |
| RCCB |
residual current circuit breaker |
| RCD |
residual current device |
| r.m.s. |
root-mean-square (effective value) |
| s |
second - unit of time |
| S |
conductor cross-sectional area |
| SELV |
seperated extra-low voltage |
| t |
time |
| TN-C |
earthing system (see 5.2.5) |
| TN-C-S |
earthing system (see 5.2.4) |
| TN-S |
earthing system (see 5.2.3) |
| TT |
earthing system (see 5.2.2) |
| U |
symbol for voltage (alternative for
V) |
| Uac |
alternating voltage |
| Udc |
direct voltage |
| Uo |
phase voltage |
| V |
volt
- unit of e.m.f. or p.d. |
| W |
watt - unit of power |
| X |
reactance |
| Z |
impedance (electrical) |
| Ze |
earth loop impedance external to
installation |
| Zs |
earth fault loop impedance |
| 0 |
phase angle |
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