Are you sure it's a microwave device, or just something that gives a HEMP?
If it's a microwave, I'd immediately think of three fault-causing mechanisms, but would assert that, potentially, each could lead to random parts failing:
1. Photo-electric effect damages electronic components directly. The device will contain at least one IC, porbably disaplay unit, and a number of ancillary components, that could well be damaged individually or simultaneously by this.
2. Localised heating damages one or more components.
3. High-energy electromagnetic pulse induces currents (and corresponding voltages).
The problem with any of these, is that I'm not sure there is a simple method to prove conclusively that it's a microwave device that did it? And I'd assume that it's possible (likely?) that more than one component will be seen to fail?
So does this mean the only way forward with these cases, is to gather empirical data on the parts damaged after exposing a suitable quantity of meters in a microwave oven, then analysing the products allegedly damaged by users to see if they exhibit a number of the failure modes characterised by microwave exposure?
Plan B - Try another approach to energy billing. Without knowing the individual circumstances, I'll throw in a couple of ideas:
1. Analogue Meter (assuming they're still available)?
2. Pre-payment type meter, so if the meter stops working, no power?
EUR ING Graham Kenyon CEng MIET TechIOSH
Principal and Proprietor,
G Kenyon Technology