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Untitled Prezi

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paul caulfield

on 12 October 2016

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Continuity of protective conductors
Test method 1
Bridge the line conductor to the protective conductor at the fuse-board and test between line and earth terminals at every appropriate point in the circuit under test as shown below:

Continuity of protective conductors
Test method 2
One lead of the test instrument is connected to the earth terminal at the distribution board via a length of test cable or ‘wander lead’. The other test lead is used to make contact with the protective conductor at various points on the circuit under test as shown below:

Continuity of protective conductors
EXAMPLE 1 – A radial circuit of length of 30m has a 4mm2 line conductor and 2.5mm2 protective. Calculate:
Continuity of protective conductors
What we are going to do now is split up into groups and using test method one do a full continuity test of all circuits on assigned distribution board.
Continuity of protective conductors
The initial tests applied to every protective conductor, including main earthing conductor, main and supplementary bonding conductors, are carried out for two purposes: Why?

Unit 304: Electrical installation: inspection, testing and commissioning

To verify that the conductors are both correctly connected and electrically sound;
To provide a measure of (R1+R2) to verify that the overall earth fault loop impedance of the circuits is of a suitable value.
a.The approximate value of (R1 + R2) for test method 1.
b.The approximate value of R2 for test method 2.
a.From the on-site guide table I1
4mm2 line with 2.5mm2 cpc= 12.02 m/ohm per per metre
r1+r2 =
m/ohm per per metre x circuit length
----------------------
1000
=
12.02 x 30
--------------------
1000
= 0.36 ohms
– A radial circuit of length of 30m has a 4mm2 line conductor and 2.5mm2 protective conductor.
– A radial circuit of length of 30m has a 4mm2 line conductor and 2.5mm2 protective conductor.
b.The approximate value of R2 for test method 2.

From on-site guide table I1
2.5mm2 cpc = 7.41 m/ohms per metre
r2 = 7.41 x 30
---------------------
1000
= 0.22 ohms
Any Questions ?
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