A modular system is described which can provide high frequency monitoring of power use and responsive control as well as enabling network connectivity for centralised monitoring and operation. One modular system consists of a communications bus, end caps, and a combination of the modules providing communications, power metering, relay control and battery backup. Each modular system can be configured with a combination of modular units as needed for the application. A combination of bus communication monitoring and tilt detection provides security against external tampering after installation.