A distribution board (also known as panel-board, or electric panel) is a component of an electricity supply system that divides an electrical power feed into subsidiary circuits, while providing a protective fuse or circuit breaker for each circuit in a common enclosure.
Each Distribution Board shall be controlled by a Switch Disconnector (Isolator).
The Switch Disconnector shall
a) be mounted in the distribution board or adjacent to the distribution in the same room / area.
b) in the case of the main or first distribution board of an installation, be labelled as "Main Switch"
c) in the case of a sub-distribution board, be labelled as "sub-main switch" or "main switch" if the board is labeled "sub-distribution board..."
d) in the case where an alternative supply is installed (emergency
supply, uninterruptible power systems (UPS), etc.), be labelled as required in 22.214.171.124 of SANS 10142
have a danger notice on or near it. The danger notice shall give instructions that the switch-disconnector be switched off in the event of inadvertent contact or leakage.
A distribution board shall not be mounted:
a) in a bathroom, except outside zone 3 and unless the enclosure provides an IP rating of IPX5 (see 126.96.36.199.6),
b) above a fixed cooking appliance or in a position where a cooking
appliance could be put below it, unless the enclosure provides a degree of protection of at least IP44, or Amdt 6
c) within a radius of 1 m from a water tap or valve (in the same room), unless the enclosure provides a degree of protection of at least IP44.
Distribution Boards come in various sizes, mounting methods, metal or plastic, and the type of Circuit Breaker that is fitted.
1) Metal Surface Distribution Board, normally used in Factory and Commercial Installations, and in Domestic Houses that are being re-wired.
2) Flush PVC or Metal Distribution Boards that get plastered in the wall.
NB: One must take care to identify if the circuit breakers to be used are the DIN (International Specification) which is becoming more popular in South Africa; or the old South African Standard which is known as the Samite or Heinemann range.
The two styles of breakers are not interchangeable, but a small Samite to DIN adapter has been manufactured so small changes may be done.
Larger Installations will require a Panel Board Manufacturer design and build the required size.
At RSA Bardo Electrical Systems (Pty) Ltd, as best method practice we try as best to leave a free space of 30% in each new board that we install. This helps if there are any future extra circuits that are installed.
Other important information pertain to Distribution Boards:
-Wiring and feeder cables or tightening of connections shall not
cause displacement of components.
-Distribution boards shall be so positioned and arranged as to ensure safe operation and maintenance.
-Text has been renumbered and moved.
- If a conductor of cross-sectional area exceeding 4 mm2 is used, it shall be so installed to allow any one neutral conductor to be disconnected without disturbing the connection of any other neutral conductor.
-A distribution board and the equipment mounted in or on it shall be so positioned and arranged that any conductor can easily be disconnected from the terminals.
- Both ends of the live conductors and of the neutral conductors of a ring circuit shall be crimped together. Ring circuits shall clearly and permanently be identified by either a notice or a tag.
-In a distribution board where the short-circuit rating exceeds
10 kA, the mechanical strength of the conductors installed between the busbars and the functional units shall be sufficient to withstand the short circuit stresses which could occur.
A conductor with a minimum cross sectional area of 16 mm2 shall be used if it cannot be shown by calculation or from the component manufacturer's information that a smaller conductor can be installed.