# Re: Repost RE: Explain 3 Phase

```Original poster: "davep by way of Terry Fritz <twftesla-at-uswest-dot-net>" <davep-at-quik-dot-com>

Tesla list wrote:

> Original poster: "Alex Crow by way of Terry Fritz <twftesla-at-uswest-dot-net>"
> <alexcrow-at-blueyonder.co.uk>

> Yes, it is 180 degrees out.

Measured from the center tap, aka ground, indeed.

> Any *electronic* engineer

I am one.

> will tell you that the two lines are 180 out of phase. The ground
> reference has *no effect* and can be ignored!

If its ignored, hooking up the scope will be interesting.
If its ignored, measurements will be end to end.
Which will show the whole to be In Phase.

> The waves are a mathematical function of time, but the "time"
> axis actually represents the "angle" input to the trigonometric
> functions.

Indeed.

> Eg the top wave could be represented as

> V1=sin(t)
>
> and the bottom as
>
> V2=sin(t+180)
>
> if, of course, you are using degrees to calculate. Most electronic texts use

OK, measured relative to the ground (center tap) is pi radians...

> The phase angle is unaffected by any static rail between
> the lines.

But the measurement is...

> Of course, I know where you are coming from, ie measuring V1 from
> Ground to the top live, then V2 from the bottom live up to ground.
> Yes, then the signals will appear to be in phase, but it's not
> something you'll find most guys doing here.

They really would be best advised to understand, if
contemplating a 240v hookup....

best
dwp

```