Should it be necessary to test the reference electrode prior to installation, it is important not to pre-test the electrode in a bucket of water as in most cases this will void the warranty. Instead the electrode can be tested in the hole or trench prior to complete backfilling, after flooding with fresh water. The electrode can be tested to a calibrated CuCuSo4 portable electrode or to the pipeline structure that the electrode is installed on, the electrode in most cases will start working fairly quickly to get a proper reading before the hole or trench is completely buried.
http://www.GMCelectrical.ne “Possible causes for reading errors in permanent reference electrodes”
