ground currents and cancer

Powerlines are associated with cancer. However, there has been some debate as to whether or not power lines can have any effect on cells because the wavelength of mains power is far too great relative to the size of cells to be able to have any resonant effect.

The following theory aims to show how the ionisation of reticulated water may be affected by AC power (the ionised water in turn affecting cells electrochemically).

As an introduction to the theory, SWER is an example of ground current in lieu of a neutral return wire:

This system reduces the cost of lines to remote installations by using earth instead of a neutral wire to complete the circuit.

It assumes that the voltage drop is small despite the resistance of ground, because at the high voltages involved the current is small.

The resistance of the earth would suggest that as the distance between the isolating transformer and the stepdown transformer increases then so too does the resistance of the return. Over short distances this is true, but it appears that over longer distances the resistance stabilises. A possible reason for this is that the return circuit involves not only a resistive return (current flowing through the ground) but also a capacitive return using the capacitance of the earth itself.

In using the earth's capacitance, a conductive return path is no longer required.

As the distance between the isolating transformer and the stepdown transformer increases (and the earth return resistance also increases), the capacitive return would take over.

Direct current (DC) would be blocked by the earth's capacitance, but alternating current (AC) is not. For example, in a radio circuit a signal may be superimposed on an AC waveform and pass through a capacitor, whereas the DC power supply would be blocked.

In a single phase residential electrical installation the return circuit is shared between the neutral wire and the ground return, the neutral and earth busbars being linked together in the meter board.

Like SWER, there are multiple return paths. In addition, the earth busbar is grounded to any conductive plumbing in the home.

Although the conductive plumbing is not directly connected to the earth wire at the stepdown transformer (pole transformer), the earth's capacitance can be used by AC to complete the circuit.

In the inductive return both impedance and capacitance come into play. Impedance is provided by the water pipe when conducting AC power.

Importantly, when impedance and capacitance are in series as they are here, the voltage in the water within the water pipe is raised.

An example of series inductance and capacitance is an electronic ballast for a fluorescent light, where the inductor and capacitor in series provide the higher voltage required to start the tube.

So in summary we could say that there are three return paths in a grounded AC system, and it is the series impedance and capacitance which has the potential to create ionising voltages.