Evershed and Vignoles Line Earth Tester

 Model LT3 cat 63348

serial no 2308429

LT3 

Line Earth Tester LT3 Made by Evershed and Vignoles. This was purchased at auction for 10 and it came with a case but without any leads or instructions. I had no plug suitable for the Bulgin 3 pin socket so dismantled the instrument to ascertain the correct connections from the wiring within (red black and green) and by making direct connections to a 13A plug was able to check that it worked on my house wiring. I have indicated the pin connections on the image below as it seems these come up for sale without the appropriate leads. I have now replaced the socket with an IEC 3pin 5A one which mates with a cable from a long gone computer. The opening in the leather case is large enough to accommodate this without any modification.

Please be aware that this tester applies a large current through the line and earth conductors without a corresponding current through the neutral so any residual current device (RCD) in the circuit will trip.

The instrument is housed in the same pplastic mulding as the BM series of Battery Meggers and incorporates the same two coil meter movement, see here: Megger BM6 The compartment at the rear being used to house two power resistors rather than a battery.





  lt3

End view showing connections to Bulgin 3pin socket  and rear compartment housing fuse and resistors.



View of interior (a second printed circuit board hidden behind scale plate)

The top board which has the two neon indicators includes circuitry to provide a DC voltage to power the electronics on the main board shown below.

View of underside main printed circuit board


How old is it? I guess this one was made in early 1980 judging by the date code on the power resistors though I believe the Lt3 was first made in about 1974. A later Mk 2 version was also produced.

What is it worth? Maybe 10-20