August 2009 - Electrical Engineering

The IEC publishes a series of documents and rules governing the preparation of documents, drawings and the referencing of equipment.   Depending on country and industry, people are either familiar with the IEC system or not.  For those not familiar it can be a little confusing at first.

Often when IEC document production is compared to methods it is mistakenly assumed the difference is simply symbols.  This is not the case.  The IEC document and referencing system is a comprehensive approach covering symbols, drawing and layout techniques, equipment references, identification of terminals and signals, classification of documents and computer data organisation.   It also goes beyond just documentation and extends into physical devices and implementation. 

I've been considering a blog on the 110 or 230 Volt issue for a while.  While browsing the Internet I came across a great summary by Borat over at  engineering.com.  He summarises the issue as:

• Historical reasons. Edison insisted on 110 V (DC) but was convinced by Westinghouse to switch to AC so that transformers (step up/down) could be used. So that became the North American standard. In Europe AEG started with 110 V (following Edison) but at 50 Hz (instead of North American 60 Hz) because it fit neater into the metric system. After WWII the voltage was doubled to 220 V because higher voltages use less copper - which was at a premium. Other countries in the world usually followed the standards of their colonizing powers. The proliferation of 110 V receptacles and devices in North America prevented the doubling of voltage but that is one of the reasons your large appliances use 220-240V plugs.