The Electrical Code

215.7 Ungrounded Conductors Tapped from Grounded Systems. Wow this is the real deal, so to beginning explaining this I need to clear up a couple of words. A dc(Direct Current) two wire circuit is basically a two wire system that feeds equipment and we know, if we have a little knowledge about electrical power that, dc red wire(power “+”) is looking for the black(negative “-“). In dc the colors change red is your hot and black is your negative. That said now we shall talk about AC(Alternate Current) power. AC has a wire(could be black, red, and blue in residential power), and for this example we are going to call this wire color black. This black wire is referred to as ungrounded. Well because if it were grounded it be shorting right there and the transformer will blow its circuit protector(breaker) and power will stop right there. This is why we have a ungrounded wires which are identified as white and green. I need to tread lightly here because in an commercial to industrial location you could have a panel with no grounded conductors feeding it. And then you might ask so how does it work right, well that is electrical theory and that is a blog all to itself and I will link to that when I get around to do that. for now what we need to know is that there are panels in commercial and industrial application that will not have a grounded wire(white or green) going to it.

“Two-wire dc circuits and ac circuits of two or more ungrounded conductors shall be permitted to be tapped from the ungrounded conductors of circuits having a grounded neutral conductor. Switching devices in each tapped circuit shall have a pole in each ungrounded conductor.”