2391 practical efli

[andy1984]

hi,

got a question about my upcoming 2391 practical.

one of the tests is an earth fault loop impedance test where you have a socket mounted on a block off wood( to plug your tester in) along with 3 switches.

the socket plugs into a 230v socket(via a flex cable and 3 pin plug) to get its power and the 3 switches put different values onto the socket where you plug your tester in.

one of the switchs gives a situation where no earth is connected and i was told that you should not proceed with the test in this situation, can anybody explain why?

and also my megger mft1502 automatically starts testing when voltage is detected so surrely it will start immediatelly when i hit the switch with no earth,thus failing me?????

please help, am confused!!!

 

[ebee]

Many modern meters check for voltage and will not allow a test if none present so earth not present should prevent the test taking place anyway.
If yours starts automatically then I would think it willl not if earth missing.
on the older meters you were supposed to notice this - some had two lamps Ph/N & Ph/E and only if both lit do you press the button to test

 

[Spark123]

If there is no earth connection when the test current is applied the exposed conductives can become live at near mains voltage, as ebee says modern testers won't allow you to do the test. iirc they also stop the test if the voltage increases above 50v, but I could be getting mixed up with something else.

 

[rockenroll]

How other mates wrote u before, many modern meters check for voltage and will not allow to test if earth is not present. I ve got MFT 1553 and I ve done home EFLI correctly and after without earth(with earth leed connected to some metal wich is not earted ex. bath tub wast), the meter will show you on the screen ERROR and all circle signs for polarity full, as u know a good polarity is when u have marked just between P and N, in this case u will have polarity marked for P, N, CPC - ERROR

Cheers

 

[Spark123]

Have I really been here this long?

 

[JohnD]

"Resurrection"