In described examples, an enclosure for circuitry includes a platform, a charge source, a first capacitive plate, a second capacitive plate, and a capacitive sensor. The circuitry is fixedly coupled to the platform. The first capacitive plate is also fixedly coupled to the platform, and either alone, or together with the platform, surrounds a volume containing the circuitry and the charge source, the charge source electrically coupled to and configured to charge the first capacitive plate. The second capacitive plate is fixedly coupled to the platform without touching the first capacitive plate, and either alone, or together with the platform, surrounds the first capacitive plate. The second capacitive plate is configured so that there is an electric potential difference between the first capacitive plate and the second capacitive plate. The capacitive sensor is electrically connected to the first capacitive plate and configured to determine when a capacitance between the first and second capacitive plates is changed.