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Posted By Topic: Conductors in parallel

DougP
Feb 09 2019 19:32

3.4.3 says "Current-carrying capacity for circuits comprising parallel multi-core cables or groups of single-core cables..." etc

The definition of a circuit - 1.4.25 "A circuit comprises live conductors, protective conductors (if any), a protective device and associated switchgear, controlgear and accessories."

The active conductors in a switchboard on the line side, supplying circuit breakers, wouldn't comprise a "circuit" -
Q1. - So the requirements of 3.4.3 wouldn't apply to them?

The definition of a final subcircuit also says that the final subcircuit starts at the load side of the protective device..

So the conductors or busbars on the line side aren't part of those "circuits".
Q2. Is there a common term for the internal switchboard wiring? All I can find is "line side".

Thanks.

   

mowgli
Feb 09 2019 19:56

Q1 isn't there another circuit from the line side out to the service fuse?

Q2 I call it switchboard wiring and I'm common as muck.
   

AlecK
Feb 10 2019 11:44

Correct the conductors upstream of final subcircuit protective devices are not part of any final subcircuit.
But they are still part of a larger "circuit", which commences at energy source (typically a distribution transformer which is part of a network and includes mains, switchboard wiring, submains, more switchboard wiring; and a final subcircuit.
For purposes of applying Wiring Rules;which only apply to an installation, we treat the installation as commencing at the "point of supply", which may be but often isn't the supply fuse that provides short circuit & fault protection for the mains.
If you're looking for definitions not in the Electricity Act, ESRs, or "3000"; ESR 4 tells us where to find them.