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. We have not used many in recent years, and it is likely that most or all sites with these modules have now been taken care of in the last 20 years. If you do encounter customer requirements for this piece, 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 – it is slightly more work to retrofit this to a module, but it is more reliable and worth the effort.
Please contact your local ETC Dealer to purchase this replacement part.