On 11/11/2011 03:25 AM, Peter Blodow wrote: > Brian, > Here in Germany, all electrical supply, home and industry, is done with > three phase current plus neutral. For single phase use, like for > apartments, the three phases are split up and each apartment or room > gets one hot leg plus neutral (plus protective earth).
Interesting - you are saying that "all" homes in Germany have 3phase power? That would mean 3 transformers instead of one - an expensive way to go for the utility company. There is some savings in distribution losses with 3 phase - and in the USA some homes are now getting 3 phase for air-conditioning and a lower rate. The thing that changes this is now inverters have dropped greatly in cost. There is little reason to pay for a 3-phase service install for a one man shop. (Newer Air-conditioners may have an inverter to increase efficiency ) The error of using safety-ground as a neutral is a common error (the most common?) - once current is flowing over the conductor, there is always a voltage drop and then a ground potential is no longer a ground potential. The rule is: Never use safety-ground as a neutral and never use a neutral as a safety-ground. Safety grounds should never have current flowing unless there is something faulty. The number of power connectors around the world is staggering. historically, most countries set up their own standard so some local company would have a cartel to produce the plugs and sockets. Some of the connectors are close enough in size that they will plug into other standards creating dangerous situations. It is also important to note that color codes for power circuits varies by county; sometimes in dangerous ways! I have a bit of this written up at: http://wiki.xtronics.com/index.php/Wire-Gauge_Ampacity#Why_was_.27hot.27_Black_in_House_Wiring.3F There is a second article related to grounding here: http://wiki.xtronics.com/index.php/Lightning_Failures_in_Transducers -------------------------------------------------------------------------------- Karl Schmidt EMail k...@xtronics.com Transtronics, Inc. WEB http://xtronics.com 3209 West 9th Street Ph (785) 841-3089 Lawrence, KS 66049 FAX (785) 841-0434 When angry, count to four; when very angry, swear. -- Mark Twain -------------------------------------------------------------------------------- ------------------------------------------------------------------------------ RSA(R) Conference 2012 Save $700 by Nov 18 Register now http://p.sf.net/sfu/rsa-sfdev2dev1 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
