Your earth connection will be treated just as is it were a protective earth connection and all of the required spacings and tests will be the same: i.e., there will be a hipot test from primary to earth and there will be spacing requirements. There will also be hipot and spacing requirements from primary to secondary. From your description, it appears that your secondary must be SELV. The normal insulation requirements must be observed between the SELV and earth which in reality is only a spacings and hipot requirement of the transformer. No hipot is required from your 12V or other SELV I/O ports to earth. ---------- From: Eric Henning To: '[email protected]' Subject: plastic enclosures & grounding List-Post: [email protected] Date: Thursday, July 31, 1997 9:40AM
Greetings all, thanks to those who replied to my INMETRO request (INMETRO = Instituto Nacional de Metrologia, Normalizacion e Qualidad Industrial (of Brazil). (From the name it appears to be analogous to our NIST) Questions via e-mail to <[email protected]> Website (in Portuguese) at: http://inmetro.gov.br President J#lio Cesar Carmo Bueno Secretary: Icla Phones: 223-8877/225-8032 Fax: 223-4283 (Thanks Rich and Art) Now, a new question. We are designing our first all non-metallic enclosed stand alone product and i am confused about the earth terminal. I don't need a protective earth terminal but need a functional earth terminal. There is absolutely no metal frames, supports etc... The ground is needed for cable shields, transient protection, etc... So i need to bring ground into the box. Can i bring it in "normally" as the third conductor of the power lines (Hot, neutral, ground)? Only call it functional ground? If so do i need to hi-pot between H+N and this ground? Or do a double insulation test? What about on the 12V circuit that has transient protection to this functional ground? I can't run a dielectric test between signal and function ground as it will naturally fail thru the transient protection. Your thougths please. This is a 120/240 VAc powered device. thanks eric [email protected]
