2.4.2 - Purposes,
supplies and structure
[Chapter
31] includes regulations which effectively provide a check
list for the designer to ensure that all the relevant factors
have been taken into account.
An abbreviated check
list would include the items shown in {Table 2.2}. Where
equipment's or systems have different types of supply, such
as voltage or frequency, they must be separated so that
one does not influence the other.
|
a)
|
The maximum demand |
|
b)
|
The number and type of live conductors |
|
c)
|
The type of earthing arrangement |
|
d)
|
The nature of supply, including: |
|
|
i) nominal voltage(s) |
|
|
ii) nature of current (a.c. or
d.c.) and frequency |
|
|
iii) prospective short circuit
current at the supply intake |
|
|
iv) earth fault loop impedance
of the supply to the intake position |
|
|
v) suitability of the installation
for it’s required purposes, including maximum demand |
|
|
vi) type and rating of the main
protective device (supply main fuse) |
|
|
e) the supplies for safety services
and standby purposes |
|
|
f) the arrangement of installation
circuits. |
|