On Saturday 13 June 2015 10:49:18 Jon Elson wrote: > On 06/13/2015 04:32 AM, andy pugh wrote: > > On 13 June 2015 at 00:09, Gene Heskett <[email protected]> wrote: > >> But 1kw and up isolation cans are both scarce, and north of a $100 > >> bill pricy at least on fleabay. > > > > eBay UK is awash with "site transformers" such as this > > http://www.ebay.com/itm/British-Made-Caroll-Meynell-3-3kva-site-tran > >sformer-/121656911146 > > > > They are used for isolation of power tools on building sites. Second > > hand ones go for less, of course: > > As you can see, UK ones are 240V to 110 step-down. Is there not a > > 110-110V version used on US building sites? > > No. I've always thought the balanced 110 V job site transformers were > a really good idea. As far as I know, they are ONLY used in the UK. > Never, ever seen anything like that at a US job site. They probably > do use GFCI protection today. > > Jon > I have a friend who built a recording studio about a decade back, but couldn't afford balanced audio everywhere. So the whole control room is on a 240-120CT transformer, with the CT grounded so its 63-0-63. Wind up a mic gain on that Mackay single ended input board and its pure white noise, and not much of that. Humm out of it is like 100+ db down.
He had a hell of a time convincing the inspectors to pass it though. Seems the NEC doesn't address such usage. I was dubious at first, but I'm a believer now. Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
