Hello Andy, current supply rings are a fine idea, but only at and above 10 to 20 kV-level. In house wiring the copper size plays almost no role as far as gross cost is concerned (labour vs. material). In my company I was responsible - among other things - for the electric power supply of, on the average, 4 MW, featuring 3 HV cables coming in from different directions, 6 stations with 17 transformers , 5 diesel- and 2 gas powered turbine generators. At this level of power and such an high demand for fail safety a ring system, connecting all transformers with a 20 kV ring cable pays. Especially the flexibility to open the ring at any place in order to exclude a faulty station or transformer, but keep the rest alive, all within fractions of a second, is invaluable. However, a ring system can only be useful if there is an indicator other than ordinary high voltage fuses to preserve their selectivity is needed. Therefore, in every power station there is what we call a "differential protection" device on both sides of the incoming cables, detecting on which side of the ring a fault occurred. These are rather expensive devices and out of discussion for home wiring. So, take a little more copper in your hand than the absolute must and build a star wiring system in your house - useful not only in grounding systems. By the way, this is the safest way to ensure that there will be no voltage present when you have switched off the fuse (no back voltage).
Peter andy pugh schrieb: > The thing is, that the main breaker for the circuit is sized for the > ring main capacity, and ring mains are bad. (oddly, this was one of > the long running arguments with my ex. She seemed to think because she > used to work for MK that her opinions were of more value than mine.) > The problem is that whilst they can give you twice the capacity for > the same wire size, there is no way to detect a wire break which > halves that capacity. > /snip/ > If I wire a house I would wire a ring using spur-rated wire CSA, I > think. Just in case. > > ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity and more. Splunk takes this data and makes sense of it. Business sense. IT sense. Common sense. http://p.sf.net/sfu/splunk-d2dcopy1 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
