Have just got a Di-log 6507 and it works fine. An electrician friend suggested we get one to help identify an EL problem we have been experiencing (slight tingle) in a copper hot water pipe coming from the unvented stainless cylinder. Question is this: It is clearly showing a current in the Earth bonding (c.1.2mA) attached to the pipe in the cylinder cupboard- but the reading on the 22mm pipe itself to which the earth clamp is attached is more like 4.5mA. Does this reading on the pipe actually mean anything? Which reading is a true figure? Can the meter accurately read ELC in the copper pipe, itself?