![]() ![]() They went with a grounded system where you intentionally peg the system to ground rather than waiting for a "first fault". Household electrical started out "isolated" because grounds were not a thing. If your accidental contact is the first fault, you only get hit with biasing current, and hopefully death "gives you a mulligan" (second chance). If another phase faults to ground, kaboom! It takes two failures to have a problem, and the idea is frequent inspection catches the first one. If one phase faults to ground, it's an unintended ground strap, and the system is no longer isolated. I have a 480V 3-phase system, all three phases isolated from ground. Industry sometimes uses isolated systems. There is a religious battle between isolated systems and grounded systems, with grounded systems winning. ![]() CodeĮnter the world of Code electrical, which applies to structures. Any leakage from the high-voltage system is considered a fault, even from the "negative" side, since "negative ground" is not a concept in an isolated system. which is fully isolated from the chassis of the car. The Prius or Chevy Volt also has a high-voltage traction electrical system - batteries, electronic inverters, motors etc. (chassis is also used as a current return that's a separate issue.) chassis) pegged to an arbitrary location in the supply power, almost always negative ground by convention. It's a 12V electrical system with ground (i.e. Chevy Volt - 2 systems at onceĪutomobiles have an apocryphal "grounded system". It's about the difference between an isolated system and a grounded system. ![]() You're starting off with a very astute observation and a valid concern. ![]()
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