Here some reply about the matter.
This is the end of a power cord of a DVD that doesn´t have the 3rd pin (ground). I didn´t used the ground aligator to the neutral just because will be redudant. It is already connected to the mains power panel neutral BAR. But, of course, i previously detected with my multimeter continuity scale, which wire is phase and which wire is neutral!
My oscilloscope has a grounded outlet pin, so, to make simple Phase to Neutral measuring, just use your probe 10x to the Phase wire, (in this case the blue one...)
The other (black wire) is the neutral, that is connected to NEUTRAL BAR-----> that is connected to GROUND BAR (all at the mains breakers box of my house).
![](https://dl.dropboxusercontent.com/u/12504158/ELECTRONICS/IMG_0355.JPG)
This is the plug to connect to the outlet. NBR5410 Brazilian standard for LV(arghhhh
![ThumbsDown :--](https://www.eevblog.com/forum/Smileys/default/icon_thumbsdown.gif)
). Anymway.
![](https://dl.dropboxusercontent.com/u/12504158/ELECTRONICS/IMG_0359.JPG)
The image below is the page of NBR5410 Brazilian standard for LV. In most of the places in Brazil, you can have 127V/220V - 60HZ in outlets.
![](https://dl.dropboxusercontent.com/u/12504158/ELECTRONICS/oscilloscope.jpg)
Before taking measures, your need to know what system does it have in your installation. Otherwise, you are blind about it, and this is potenttialy dangerous!!!!
In this case (Phase to neutral) you can have a safe measuring of your outlet...(Does anyone desagree with it the results are not accurate?)
![](https://dl.dropboxusercontent.com/u/12504158/ELECTRONICS/IMG_0356.JPG)
![](https://dl.dropboxusercontent.com/u/12504158/ELECTRONICS/TEK0002.JPG)
By other hand,if you only have an outlet that delivers phase to phase and ground (220V) it is recomended that you use the method shown in the video. (diferential method), or use a 220/127 to 6V transformer, (from a old device), or whatever isolated transformer you have.