Earthing system used in Sri Lanka is TT. It means supply authority does not provided the earthing conductor through out their distribution. In other way, electricity consumers should be provided the earthing conductor & earth electrode them selves. If we have a system/ device/ machine ( for an example: lift control system ) which was originally designed for TNS, that system whether can be connected/energise to the power supply having with TT. If it is possible to connect to the power supply where the system you get TT, Are we need to make an attention about the earthing....( if specially filters has been used in built in the system.)