Underground cables on the Southern Upland Way

We found a set of underground cable markers on the Southern Upland Way west of Moffat. I went looking for information about how deep they were buried but found this instead http://www.emfs.info/sources/overhead/specific/132-kv/ Click on the "underground" option. I cannot verify this data. Maximum magnetic field strength would be less than 10 microTeslas. The strength of the Earth's magnetic field is between 25 and 65 microTeslas so I don't think the reported reading is significant. I need to take my magnetic field measured if I go again!