I've just noticed this post after some time away from the forum. I have been asked by a few clients whether electromagnetic energy from the home power supply could be affecting earth energy patterns or vice versa. I've never found a case of this, so I'm doubtful.
What I have found is a lot of homes with so called "stray voltage" pathways, caused by any number of wiring errors, poor ground connections, and undersized neutral wires. Errant magnetic fields can crop up all over the place, some caused by hot and neutral wires leading to some location not in close proximity as they should be (where they would normally cancel out each others' counter-rotating magnetic fields). Or they can be generated simply by the collapsing electric fields inherent in AC or pulsed/switched DC power, since electric fields can generate magnetic fields and vice versa when conductive metals are nearby.
In this case, where simply switching on an appliance causes an extensive power flow (probably underground through conductive soil or possibly partway along a metal pipe), the circuit powering the cooker may be grounded properly but still have a neutral wire that is corroded. This would prevent all of the power used from traveling in the preferred pathway through the house wiring. Some could flow through the ground connection and into the home's main grounding point. This point could be a water pipe or a dedicated ground rod. From there the power would flow toward either the nearest other ground rod in the neighborhood, the nearest utility pole ground, or the nearest water pipe that's also grounded.
Here in the States the problem is so common in some areas that many states have formulated their own laws indemnifying local utility companies from damage, injuries, or deaths caused by stray voltages. Not long ago I diagnosed a large magnetic field in two commercial buildings owned by a local plumber. They turned out to be cases where poor neutral conductivity was causing major power flows through the incoming water pipes. The plumber had just lost a fellow plumber in a neighboring state to death by instant electrocution when he unknowingly touched the incoming water pipe and a repaired section of pipe that acted as the main power ground for the building. The living plumber quickly repaired the incoming pipes with 7-foot sections of non-conductive pipe (so that a human's 6-foor reach couldn't touch both sides at once) and placed the main ground wires on the outdoors side of the conductive section of pipe, restoring the normal grounding path. The repair also solved the problem of the huge magnetic fields that sometimes occurred along the building's water pipes.
What I'm trying to say is that this is tricky and potentially deadly stuff that should be left to those who understand, can visualize, and can meter the faults and take precautionary action. Just asking for this to turn positive won't do it!
"Develop an infallible technique, then place yourself at the mercy of inspiration." (from a craftsman, but it applies widely)