Capstone - Earthing Flashcards
AS/NZS 3000 clause 5.1.3 states that the neutral in an MEN system is to be earthed at which point(s)?
1 - At the source of the supply
2 - At regular intervals throughout the system
3 - At each electrical installation connected to the system
Within an electrical installation, what is the earthing system connected to?
Exposed conductive parts of equipment
What is the IEC term used to describe the MEN system?
TN-C-S
In a TN-C-S system, where is the point of connection at ‘T’ and what is the part of the system that is connected?
Neutral point of the supply transformer, distribution system
In a TN-C-S system, where is the point of connection at ‘N’ and what is the part of the system that is connected?
At MEN connection, exposed conductive parts
In a TN-C-S system, what is meant by ‘C’?
Neutral and protective conductor functions are combined in a single conductor (the neutral conductor of the distribution system)
In a TN-C-S system, what is meant by ‘S’?
Protective conductor function separate from neutral - separate conductors within the installation
Where will there always be an MEN link, main earth, and earth electrode?
Main switchboard
Where will you always find a PEN conductor?
Upstream of an MEN link
What is a PEN conductor?
Protective Earth Neutral - single conductor that functions as both neutral and protective earth
What other systems are used (outside Australia) besides TN-C-S?
TNC, TNC-S, TNS, TT, IT
A structure containing a switchboard separated by an area of land from the structure containing the switchboard that supplies it is known as what?
Individual outbuilding
Any number of structured installed/built on the same foundation, sharing conductive metal roofing or conductive metal frames, with more than one electrical supply, separated by an area of land from another structure that contains the switchboard that supplies them is known as what?
Combined outbuilding
Outbuildings are required to be earthed in accordance with which AS/NZS 3000 clause?
5.4
Individual outbuildings may be earthed by either connecting to a PEN, or as a separate MEN installation - True or False?
True
Combined outbuildings may be connected to a separate MEN system, True or False?
False
How shall combined outbuildings be connected to an MEN system?
Via a protected earthing conductor
Which AS/NZS clauses define earthing requirements for individual and combined outbuildings?
5.5.2.1, 5.5.3.1, 5.5.3.2
If a protective earth conductor is fed to a distribution board, is an MEN link required?
No
If a protective earth conductor is fed to a distribution board, is a main earth and earth stake required?
No
If a protective earth conductor is not fed to a distribution board, what is required to meet earthing requirements?
An MEN link, main earthing conductor, and earth electrode.
If a distribution board has a separate MEN installation, the submain neutral becomes a _______.
PEN
When is a PEN effectively a protective earth?
Under fault conditions
When is a PEN effectively a neutral?
Under normal conditions
If a second outbuilding is supplied by the distribution board of another outbuilding, the PEN of the second outbuilding may rely on the terminals of the neutral link of the first outbuilding - True or False?
False
PENs are never connected (ie soldered) to other neutrals at the main switchboard, True or False?
True
What does the AS/NZS 3000 clause 2.10.5.4 define regarding MEN connections?
That the terminals for connection and for the main neutral conductor shall be legibly and indelibly marked at the main neutral bar
What is an exception to the AS/NZS 3000 clause 2.10.5.4 regarding marking of MEN conections?
Where MEN connections is made at a terminal at one extremity of the bar and the main neutral is placed to the next adjacent terminal
How will the PEN of a second outbuilding be connected to the neutral link at the first outbuilding to comply with AS/NZS 3000 requirements?
It will be soldered
