The integration of volatile renewable energy into distribution networks on a large scale will demand advanced voltage control algorithms. Communication will be an integral part of these algorithms, however, it is unclear what kind of communication protocols will be most effective for the task. Motivated by such questions, this paper investigates how voltage control can be achieved using event triggered communications. In particular, we consider online algorithms that require the network’s buses to communicate only when their voltage is outside a feasible operation range. We prove the convergence of these algorithms to an optimal operating point at the rate O(1/τ), assuming linearized power flows. We illustrate the performance of the algorithms on the full nonlinear AC power flow in simulations. Our results show that event-triggered protocols can significantly reduce the communication for smart grid control.