Taken from page 6 of the KT63 manual;
Special polarity test function.
It is a little known fact that a system can be reverse wired with Line (Phase) to earth/neutral and earth/neutral to Line (Phase).
The sockets will all work and conventional loop testers will show and test that everything is correct despite this very dangerous wiring condition.
Although extremely rare, this miswire condition can exist so if your test shows this fault do not proceed – if in any doubt advise your customer to contact their supply company immediately.
Audible tones
A simple selection of audible tones is used to supplement the visual display. These help the user by providing intuitive feedback during testing. In addition to warning about dangerous or unstable supply conditions they provide a very quick confirmation that the measurement process is taking place and, upon completion of the test, a warning if the results are likely to be regarded as a failure.
The meaning of the tone for each individual function is covered in detail in the relevant
section. Generally however there are five types of tone emitted.
Danger
A rising siren type alarm
In the event of a potentially dangerous situation such as connecting to a live supply when configured for insulation
testing. Will be accompanied by the Red Voltage/Polarity warning LED flashing.
Warning
A continuous 2 tone alarm
An unsuitable supply configuration such as a mains supply with incorrect polarity or having the leads connected wrongly will be accompanied by the Red Voltage/Polarity
warning LED flashing.
Wait-Test in progress
A steady beeping sound Emitted whilst a measurement is in progress. The same
tone is sounded when used in Handsfree mode to indicate that continual measurement is being made
Test completed
A single beep
Sounded upon completion of ameasurement to indicate that the result is being displayed
Alert
A short 2 tone alarm
Sounded when a test returns a result that is likely to be regarded as a failure e.g. An insulation test that gives a result of less than 2 MΩ