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Yes it is, if you want to know the power direction. You can see what the original wiring was in my report in Building Blocks. You'll only kill yourself (probably not, but you do risk a painful shock) if you open-circuit the c.t. whilst it is clipped onto a current-carrying conductor.

Hey Robert,

Thanks for your help again!  Do you mean this article?  Sorry, I like to be extra certain what mistakes not to make.

http://openenergymonitor.org/emon/buildingblocks/report-yhdc-sct-013-000...

What do you mean it's important if I want to know the power direction?  Should I care about direction?  I just want a scalar quantity of power to be measured at the end.

Thanks so much.

Tyler

...Feeling overwhelmed on what seems to be basics to most people

Yes, that's the article. Sorry about the power direction bit. If you have the ability to generate, either with PV, hydro, wind or whatever, then most people like to know whether they are importing or exporting power, and to do that you need to measure the voltage and compare the instantaneous direction of the current compared to the voltage. If you're not interested in the direction of power flow (which you won't be if you cannot generate), then the phase (as we call it) of the c.t. doesn't concern you. The emonTx_CT123_Voltage sketch does give you power direction (it shows as positive or negative) so if it's wrong, the easy way to change it is to reverse the c.t on its mains cable, no wiring change required. If you want to gen up on power flow: An introduction to AC Power

I forgot to mention, normally, the plain copper screen in the c.t. cable isn't connected. You can connect it to the sleeve of the plug if you wish along with the red wire. I didn't realise I hadn't put the wire colours on the diagram - I've just added them in the text.

And sorry about the overwhelming too. Building Blocks is where the theory is, from the basics to some quite complicated stuff. Don't be afraid to ask if you don't understand, that's how you learn.

No, I LOVE the building blocks page.  It's just that I've always learned that electrical engineering is not a place to dink around in my mech engineering schooling.  So I haven't.  Thereby, some of this is from the ground up.  For example I had no idea about 3 phase electricity or why it's generated.  I had no idea about why the capictor was needed.

To complicate matters, I hate frying electronics.  Nothing like seeing smoke emerge from a circuit and frying your board!

I'll do some more reading on the page before I try it.  I'm going to run the AC Current only sketch first and then wire in a transformer I bought to step down the wall input to 9v.  I noticed my SCT-013-000 has the copper shield like you mention and I've just twisted that together and as you said, I have red and white.  From reading about the 3.5mm jacks and looking at the end of the SCT I clipped off, it appears red and copper are soldered to the ground on the jack and the short pin is soldered to white, which appears to carry the signal to the tip (positive).  Judging from the wiring to the Arduino, I'm guessing the white goes with the 5v side and the red/copper goes to the ground?  Is that correct?  Thanks for everything sir.  You're a blessing to those of us electrically challenged engineers that are still pissed about their power bill and trying to find the problem!

Nothing like seeing smoke emerge from a circuit and frying your board!  Did you not know that all things electrical run on smoke? It stands to reason: when the smoke comes out, they stop working, so they must do.....

[That joke is probably older than me!]

Judging from the wiring to the Arduino, I'm guessing the white goes with the 5v side and the red/copper goes to the ground?  Is that correct?

No, look again at CT sensors - Interfacing with an Arduino - that shows exactly how it is connected.

Thanks Robert, I think I didn't see the orange current loop last time, so I was guessing since I don't "see" the flow well.  Thanks!  I'm still learning, so I appreciate the time you take for me.