Abstract: An automatic meter reader (AMR) used in an electrical distribution system has a communications module (26, 28) housed within an enclosure (12) for two-way message communications with a utility (U) to report information to the utility concerning electricity usage at the AMR site. The communications module includes at least one resistive element (RR) which may have an associated heat sink (H) and to which current is supplied during communications. A heat flow control (30) used with the resistive element controls the release of heat generated thereby during a message. This includes applying at least one layer (L) of a phase change material (PCM) to the resistive element, or its heat sink, to control the increase in temperature of ambient air inside the AMR enclosure during two-way communications to a temperature below a critical temperature (Tmax). This allows a message of greater length to be used for communications between the utility and AMR than was previously possible.