OP
Zenn
JUNE 2010:
Section B:
The owner of a small industrial unit requires an additional exterior lighting circuit to be installed for security purposes. At the same time the existing electrical installation is to be inspected and tested in order to obtain insurance cover for the premises.
The electrical installation forms part of a 400/230 V TN-C-S system with a Ze of 0.1Ω and a PFC of 4.6 kA. The existing installation comprises 70 °C
thermoplastic insulated single core copper cables contained within a steel trunking and conduit containment system.
A separated cpc is installed for each circuit and is contained within the trunking and conduit.
The three-phase DB is located at the origin of the installation and contains a mixture of BS EN 60898 circuit breakers and BS EN 61009 RCBOs.
Figure 1 Below shows information on the resistance of conductors in mΩ/m
______________________________________
Conductor csa (mm2) | mΩ/m at 20°C
_________________________________
1.5 .......................12.10
2.5 .......................7.41
4.0 .......................4.61
6.0 .......................3.08
10.0 .....................1.83
_________________________________
1.
a) List the documents that must be completed and issued to the client on the completion of the electrical work.
b) List the parties who would be involved in determining the extent and limitation of the inspection and testing of the existing installation.
c) state where the decision reached in (b) above is to be recorded.
d) state the
i) title given in law to the inspector.
ii) legal status of the inspector.
e) List three items of information which must be available to the inspector regarding the distribution network operator's equipment.
_____________________________________________________________________________
2.
a) One part of the building has an area where chemical etching and washing down takes place.
i) List three factors which must be considered when inspecting the containment system in this particular area.
ii) Identify, for each of the factors given in (ai) above, the human senses that would best determine compliance.
b) The owner has agreed that the whole installation may be isolated in order for testing to be carried out. There has been period of one hour
allocated for this work.
List the tests that must be carried out during this period (individual circuits may be isolated after this period)
___________________________________________________________________________________
3. A test of continuity is to be carried out on the main protective bonding conductor to the gas service located 30 (m) from the origin of the
installation.
Describe how this test is to be carried out after safe isolation has been completed. your answer should include
a) initial safety precautions
b) instrument used
c) test procedure
d) final safety procedures.
_________________________________________________________________________________
4. A continuity of ring circuit conductors test is to be carried out on the circuit supplying the office.
The circuit is wired in 2.5 mm2 cable with a 1.5 mm2 CPC. The loop length of the cable is 65 m. All socket outlets are connected directly on the
ring.
Explain in detail, using the information given in figure 1, the three steps required to confirm the continuity of this circuit.
your explanation should include the
. Test instrument
. Test connections and the expected reading at each stage.
Show all calculations.
________________________________________________________________________________
5. Draw a fully labelled diagram showing the complete earth fault loop path for the newly installed lighting circuit. the diagram should identify the
a) Correct system
b) Complete fault path
c) All the component parts of the earth fault loop.
_________________________________________________________________________________
6. During the course of the inspection one of the single phase radial circuits supplying an item of fixed equipment is to be checked for voltage
drop compliance. The circuit has the following characteristics.
. Load current = 45 A
. Circuit length = 80 m
. Live conductors = 10 mm2
a) Using the information in figure 1 determine whether the circuit meets the requirements for voltage drop. show all calculations.
b) State
i) A suitable observation to be recorded on the periodic report if the voltage drop fails to comply.
ii) One action which could be taken to rectify the situation in (b,i) above.
Section B:
The owner of a small industrial unit requires an additional exterior lighting circuit to be installed for security purposes. At the same time the existing electrical installation is to be inspected and tested in order to obtain insurance cover for the premises.
The electrical installation forms part of a 400/230 V TN-C-S system with a Ze of 0.1Ω and a PFC of 4.6 kA. The existing installation comprises 70 °C
thermoplastic insulated single core copper cables contained within a steel trunking and conduit containment system.
A separated cpc is installed for each circuit and is contained within the trunking and conduit.
The three-phase DB is located at the origin of the installation and contains a mixture of BS EN 60898 circuit breakers and BS EN 61009 RCBOs.
Figure 1 Below shows information on the resistance of conductors in mΩ/m
______________________________________
Conductor csa (mm2) | mΩ/m at 20°C
_________________________________
1.5 .......................12.10
2.5 .......................7.41
4.0 .......................4.61
6.0 .......................3.08
10.0 .....................1.83
_________________________________
1.
a) List the documents that must be completed and issued to the client on the completion of the electrical work.
b) List the parties who would be involved in determining the extent and limitation of the inspection and testing of the existing installation.
c) state where the decision reached in (b) above is to be recorded.
d) state the
i) title given in law to the inspector.
ii) legal status of the inspector.
e) List three items of information which must be available to the inspector regarding the distribution network operator's equipment.
_____________________________________________________________________________
2.
a) One part of the building has an area where chemical etching and washing down takes place.
i) List three factors which must be considered when inspecting the containment system in this particular area.
ii) Identify, for each of the factors given in (ai) above, the human senses that would best determine compliance.
b) The owner has agreed that the whole installation may be isolated in order for testing to be carried out. There has been period of one hour
allocated for this work.
List the tests that must be carried out during this period (individual circuits may be isolated after this period)
___________________________________________________________________________________
3. A test of continuity is to be carried out on the main protective bonding conductor to the gas service located 30 (m) from the origin of the
installation.
Describe how this test is to be carried out after safe isolation has been completed. your answer should include
a) initial safety precautions
b) instrument used
c) test procedure
d) final safety procedures.
_________________________________________________________________________________
4. A continuity of ring circuit conductors test is to be carried out on the circuit supplying the office.
The circuit is wired in 2.5 mm2 cable with a 1.5 mm2 CPC. The loop length of the cable is 65 m. All socket outlets are connected directly on the
ring.
Explain in detail, using the information given in figure 1, the three steps required to confirm the continuity of this circuit.
your explanation should include the
. Test instrument
. Test connections and the expected reading at each stage.
Show all calculations.
________________________________________________________________________________
5. Draw a fully labelled diagram showing the complete earth fault loop path for the newly installed lighting circuit. the diagram should identify the
a) Correct system
b) Complete fault path
c) All the component parts of the earth fault loop.
_________________________________________________________________________________
6. During the course of the inspection one of the single phase radial circuits supplying an item of fixed equipment is to be checked for voltage
drop compliance. The circuit has the following characteristics.
. Load current = 45 A
. Circuit length = 80 m
. Live conductors = 10 mm2
a) Using the information in figure 1 determine whether the circuit meets the requirements for voltage drop. show all calculations.
b) State
i) A suitable observation to be recorded on the periodic report if the voltage drop fails to comply.
ii) One action which could be taken to rectify the situation in (b,i) above.
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