In September 2016, it was decided to retire a part used as an “upgrade” for very old Sensor modules. Part#s 7050A1028 and 7050A4049 Module Circuit Breaker Insulators will no longer be available. Instead, 7050A4080 - SNSR MOD SHIELD CIR BREAKER should be used.
In the early days of Sensor in the US (around 1993-1994), we discovered that the bare open end of the circuit breaker could very occasionally arc to the metal of an adjacent module during a short circuit. This was quite a destructive failure, so we added a piece of Nomex® as a quick fix to allow the modules to operate safely. We recommended that people upgrade modules in the field.
We have now decided to obsolete this Nomex® piece. If you do encounter ETC Dimmer Modules that do not have insulation over the circuit breaker, our new recommendation is to use 7050A4080, which is the plastic piece which serves this purpose in new modules. It is much more robust and a better solution to the problem. This part has been in use since about 1996.