4
9
3.1 Front View
(see Figure 1)
Correct Wiring Indicator
– Indicates the correct wiring of the
socket outlet under test by displaying three green Light emitting
Diodes (LED’s) and a continuous tone for 3 seconds.
Incorrect wiring is indicated by a series of orange or red flashing
LED’s and an intermittent tone being emitted.
Wiring Indictor Reference Chart
– Helps identity the most
common fault conditions and how they are displayed by the
instrument.
Voltage indicator
– Indicates the range of the voltage using the
ranges specified by British Standard BS7697:1993
(Nominal
voltages for low voltage public electricity supply systems).
Earth – Loop Indicator
- On pressing the Earth – Loop Test
Button, an indication of the range of the earth – loop impedance
will be displayed.
Polarity Test Pad
– On completion of all other tests, firmly
pressing the ‘Test Pad’ will confirm the polarity of the supply
system.
Earth – Loop Test Button
– pressing this button starts the Earth
– Loop test.
WARNING:
The TPI 85 Multi-Function Earth Loop Tester is a mains powered
instrument and therefore does not incorporate an internal battery.
There are no user serviceable parts inside the instrument and
therefore the rear case of the instrument should not be removed.
Acceptable Earth-Loop Impedance results depend on the type of
circuit and the circuit protective device (fuse, Miniature Circuit
Breaker [MCB] or Residual Current Device [RCD]) employed to
protect the circuit under fault condition. Recommended Earth Loop
Impedance results are detailed in British Standard 7671 (IEE
Regulations) however, for guidance the indications displayed by
this unit are discussed below
:
<1
W
Any Earth Loop Impedance values of less than 1 Ohm
can be considered acceptable and should be found in
about 90% of most domestic electrical installations.
<10
W
This is still normally considered to be an acceptable
reading, but it may indicate a loose earth connection and
it may be worth checking the adequacy of the
connection at the point of test. If the point of test is at the
extreme of the electrical circuit, then earth – loop
impedance readings can be expected to be higher.
<100
W
Such a reading should cause concern and should be
investigated. However, if the electrical supply system is
fed via overhead cables (known as a TT supply system)
and an earth is provided via a spike driven into the
ground, then the reading may normally be considered as
acceptable.
<200
W
For any other supply system than a TT (as discussed
above) this must be considered as a serious earth fault
and should be investigated and corrected. Where a TT
supply system is employed, providing the circuit is also
protected by a Residual Current Device (RCD) rated at
either 30mA or 100 mA then the reading may normally
be considered as adequate.
>200
W
Any results exceeding 200 Ohms need to be investigated
and resolved as a matter of urgency.
NOTE:
In the event of a concern about an electrical installation
please consult a qualified electrician.