The reality is that there are well over 100, perhaps hundreds, of IEC standards are in use, or under evaluation for use, in the US. (See ANSI Standards Search or UL standards catalog.) Why has taken many years and work is still needed for the use of IEC standards to achieve even the current level in the US? The primary reason is:
History – there is a long history behind the existing extensive inventory of standards developed and used within the US electro-industry. These standards were developed to reflect the US products and practices by the likes of UL, IEEE and NEMA. In some cases, like electric shock protection (fibrillation vs. let-go) and earthing, the general philosophy, while constrained by physics and physiology, grew up differently from other parts of the world and thus the standards were written to reflect that philosophy. Once these basic principles were entrenched, standards developed later continued to reflect and build on those criteria.
There are ongoing efforts to compare the US and IEC requirements so that hybrid standards can incorporate the best of both worlds but still address US needs. This activity requires time and commitment to stay with the effort until it is complete. If you want to be part of this effort, contact the US National Committee (USNC) Secretary – Mr. Charlie Zegers at email@example.com or (212) 642-4965. Alternatively you can access the directory of the USNC to identify the key contacts (Technical Advisor or TAG Administrator) for individual activities at USNC Directory.