I find this (that there must always be ground continuity across and isolation transformer, and that one end of the secondary must be connected to neutral) unlikely. There are at least five circumstances in which this doesn't apply under UK regulations, and I am pretty sure that the same situations apply in the USA.
The first is Separated Extra Low Voltage (SELV - e.g. the common or garden wall wart). The second is the common or garden bathroom shaver socket. The third, is class IT systems, which have no earth at all, and are required in certain areas of hospitals. The fourth is special non-conducting environments, where it is physically impossible to touch more than one conductor at a time. And the fifth is environments where all exposed conductors are bonded together, but not to the supply earth. The last two are specialist cases. Jim Brown wrote: > Aside from the fractured logic in this sentence, power isolation > transformers, installed per NEC, do NOT isolate the green wire on one side > from the green wire on the other, because code requires that ALL grounds > (including all green wires, and the chassis of all equipment) be bonded > together! > > NEC also requires that the neutral of every transformer secondary must be > bonded to ground, and as noted above, all grounds must be bonded together. > So the question is, what, exactly, from a grounding perspective, do you > expect to gain by using an isolation transformer? > -- David Woolley "we do not overly restrict the subject matter on the list, and we encourage postings on a wide range of amateur radio related topics" List Guidelines <http://www.elecraft.com/elecraft_list_guidelines.htm> ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
