Inspections & Testings

INTRODUCTION:
Inspection and testing play an important role in electrical wiring. It give details condition devices,if there is any burn out or loose of contact, then the necessary action can taken. Testing  is the way of identifying continuety in a electrical system or devices.

 Inspection is the checking of all control panel, bus bar and distribution fuse board to confirmed all the connection was made correctly to avoid risk of short circuit or potential contact of cable inspection is important because it can happen the short circuit or partial contact of terminal which lead to fire out break or not allowing power supply to be deliver to the load. During the inspection you may observe wrong connection or partial contact more especially neutral, which lead to absent of power supply.

TESTING: It consists of several testing equipment with the aim to confirm the electrical wiring of the build was ok and safe. One of most important of testing is continuity ,this will give assurance that all the cable have continuity as per as connection concern, it means if power supply deliver to the, no any abstract make sure , before carrying out  continuity the load is not connected to the supply. And also change tap change of your multi meter to continuity test.

 Calibration zeroing and care of testing device for calibration: is the system which allows user to select his desire quantity such as dc or ac and it can be current, voltage and resistance. This is important because you cannot use resistors Calibri for voltage.

Zeroing is the position instrument to zero position after taking reading. It makes next reading accurate and correct,

Care for instrument: if the testing instrument used dc source such as battery, you must care for the life time of battery, if it is weak, it can cause your testing instrument to give incorrect reading. Most modern testing instrument has battery indicate .if it is weak, this is great achievement. Now I will like to state different test to be carried out for proofer and stand electrical in building or industries.

A-Continuity of protective conductor

B-Continuity of ring find CCT conductor

C- Insulation resistance

D- Protection against resistance

E -Polarity

F- Earth electrode resistance.

G-Earth fault impedance

H-Prospective fault current

J-Functional testing

a- continuity of protective conductors: at the D.F.B joint together the phase conductor and its association C.P.C   using a 10 resistance ohm meter test between phase &circuit protective conductor (CPC) at all the outlet circuit.   

B- Continuity of ring final circuit conductors bases on the principle that resistance change with a change in length and cross-section area (CSA) we can use the following method:

Take two conductors TPN and ABC and take their resistance values figure 1.0

                                         

 

Then double them both over join the end TN and AC as follows:

T               P                        A

   

TEST PRODUCE IS AS FOLLOW:-

1-observe the resistance of both conductor and budge together phase and neutral at the midpoint socket (this corresponds to PB in figure 1.1) now take reading between complete phase $neutral ends in the D.F.B (point TN and AC in fig 1.1) record this as R2. For healthy ring circuit approximately half of R1 should be value of R2 should be quarter of R1.

Protection against direct contact by barriers or en closure: by using British standard finger you can connect in series with lamp and supply of not less than 40v and not greater than 50v the test finger is pushed into or behind the enclosure barrier and the lamp support not on. This can eliminate leakage current. Insulation  resistance.

An insulation resistance tester which is a high resistance ohmmeter, Care must be taking in carrying out this test.

Phase to earth procedure:

-ISOLATE the supply

-make sure the entire protective device is in place and all switch are off

-ling all pole of the supply together

-Test between the linked poles and earth as illustrated bellow:-

    

                               

                          



SINGLE PHASE       0.5M 2M

BETWEEN POLE:

-Isolation supply

-Make sure all protective devices are in place and all switch are closed

-Remove all bulbs equipment

-Test between poles

The test procedure was shown:-                                                          

                                      

                                    

POLARITY: this is important to confirmed all fuse and single pole device such as single –pole MCBS and switch are connected in the phase conductor only.

Functional Testing; prospective short-circuit current APSCC tester normally incorporated with a loop impedance tester is used for this. To conduct the test at the intake position problems or clip will be needed and hence great care needs to be taken when connecting to live terminal measurement are taken between P & N.

Residual current devices (RCD): Care must be taken when conducting above test because an intentional earth fault is produce in installation.

The test is as follows:

-Fester should be set to the RCD rating half the rated tripping current is passed through the device it should not trip

-Pass through full rated tripping current to the to the RCD it should within 200ms

-RCD has a test button which should be operated to confirm the accuracy of its tripping mechanism. It does check any part of the eating arrangement tester quarterly.