Loop Test; Rcd's In The Circuit Under Test - Martindale Electric EZ165 Instruction Manual

3.3.2. Loop Test

If the wiring is correct and the supply voltage of the circuit under
test is between 195V and 270V the lower indicators will all indicate
green and one of the top indicators marked LOOP TEST will
indicate the range into which the measured earth loop impedance
falls.
For example if the top centre indicator is green then the measured
earth loop impedance of the circuit under test is between 1.7Ω and
5Ω, or if the top left-hand indicator is red then the measured earth
loop impedance is between 10Ω and 100Ω.
Refer to the latest edition of the IET Wiring Regulations (BS 7671),
to determine if the indicated earth loop impedance of the wiring
under test meets the necessary requirements.
Figure 3. Loop Test Indicators (Top LED's)

3.3.3 RCD's in the Circuit Under Test

The EZ165 should operate satisfactorily on circuits protected by
most 30mA or higher RCDs or RCBOs.
8
0 - 1.7Ω
1.7 - 5Ω
5 - 10Ω
10 - 100Ω
100 - 200Ω
200 - 500Ω
Wiring fault or voltage
<195V or >270V