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TESTING AND VERIFICATION

 

RISK ASSESMENT

ISOLATE SUPPLY                                  -Lockout and tagout etc

PREPARE PPE                                        -Rubber Mat, witches hats, gloves (test gloves to be air-tight), LV rescue kit (check contents) spotter –give crook to him/her, cotton drill long sleeve pants and shirt

PROVE TO BE DEAD                                             -Test meter , test board, then re-test meter

--------------------------------------------------------------------- REMOVE PPE ------------------------------------------------------------------------

VISUAL                                                                  -cable sizes, identification, sheathing, route (how + where they are run)
-CB sizes, ratings
-Earthing + MEN + Main Earth + Main Nuetral positions + Earth Stake- depth etc.
-Tighten screws, IP rating (uncovered screws etc)
-Everything fit-off (whole installation)

EARTH CONTINUITY                                         

--------------------------------------------------------------REMOVE MAIN EARTH AND M.E.N -------------------------------------------------------------------
-Check calibration of meter (ok if less than 6 months old)
-check trailing lead on Ω scale, measure main earth from earth stake to board. (0.5 Ω or less)
- measure equipotential bonding conductor (0.5 Ω or less)
-measure subcircuit earth resistance at each point (must be low enough to trip CB)
-----------RECORD EARTH RESISTANCE OF FURTHUREST POINT OF EACH CIRCUIT ON FAULT LOOP IMPEDANCE SHEET--------
---------------------------------------------------------------RECONNECT MAIN EARTH--------------------------------------------------------------           

INSULATION RESISTANCE                 
-Turn all CB’s off, turn all switches on, Remove any solid state devices or sheathed heating elements
-using megger set scale to twice the voltage and prove it works
-attatch earth probe to earth bar and test                      Mains:    A > E,   N>E
Sub Circuits:         A>E,     N>E
-1MΩ or more is needed
-megger heating elements         -0.01MΩ or more for heating elements is needed

 

POLARITY (with correct connections)             -Check trailing lead using Ω meter   Check polarity of:
Consumers Mains:                 main A>main A,
main N>main N
Power Sub Circuits:             A>A
(prove to be switched)
---------RECORD ACTIVE RESISTANCE OF FURTHUREST POINT OF EACH CIRCUIT ON FAULT LOOP IMPEDANCE SHEET---------
N>N
(prove to be not switched)
Lighting Circuits:  AS ABOVE
All Other Circuits:                AS ABOVE

EARTH FAULT LOOP IMPEDANCE                     -using the resistance values for the furtherest point of each circuit (previously recorded)
-Add the values of resistance of A + E for each circuit together.
-see table 8.2 (p325 AS3000) for max. values of resistance allowed (Rphe) for    the CB used for that circuit                                                                     
----------------REPLACE ALL CABLES, TIGHTEN ALL SCREWS, REPLACE MEN, TURN ALL CB’s + MAIN SWITCH OFF----------------

INTERCONNECTED TEST      -Turn on supply- test for correct voltages       A>E 240v, N>E 0v, A>N 240v
-turn on main switch, and first CB, then check that all other CB are dead
(repeat this for the rest of the CB’s)
-check meter
-----------------------------------------------------------REPLACE COVER-------------------------------------------------------------------------------

RCD TEST  -turn all circuits on, using RCD tester check every power and every light fitting
-record disconnection time and check that it meets requirements (max tripping time for type 2 RCD is 300ms (p43 AS3017))
- press the manual trip button on each RCD and prove that it trips.