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.