# Piggyback Plug - Series or Parallel



## BrotherBart (Mar 23, 2009)

My Stove Stat has a broken wire right where the cord goes in the molded piggyback plug. I find replacement plugs with cords but they come in either series or parallel. The Stove Stat turns the power on or off to whatever is plugged into the outlet side of the piggyback plug.  Is that a series setup, as I suspect, or parallel?


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## John_M (Mar 23, 2009)

Bart, If the original wiring was connected hot to hot and neutral to neutral, it was a parallel connection. I am not certain this answer gives even a teensy bit of help to your question because I am unfamiliar with the setup you describe. But I do hope I helped a little. 

John_M


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## Gooserider (Mar 23, 2009)

You will need to do a bit of digging to figure that out BB...  Do you have an ohm-meter, or a continuity checker?  Essentially what you need to do is figure out what the original wiring was and try to duplicate it.

On the standard electrical plug you will have two or three prongs - two flat and one round or "U" shaped - the round one is ground, and unless something is wrong, it should NEVER have current on it.  (This is why it doesn't have to be there, it is only for protection, and if the device has other protections built in the ground isn't needed)

Of the two flat prongs, one will be wider than the other, it may sort of flare out at the end - this is the NEUTRAL wire, it provides the return path for the electrical current after it has passed through the thing being powered.  In a circuit, it should read zero with respect to the ground wire, or very close to it.

The narrow flat prong is the HOT wire - it carries electrical power TO the device.  It should read line voltage (110 VAC) with respect to EITHER the neutral or ground wires.

From your description, I'm assuming that this gizmo is a small box, like a wall wart with prongs to plug in to the outlet on one side and a female receptacle on the other, with a wire running off to a sensor that you put on the stove...  Is this correct?

If so, what I'd expect is that your hot and neutral wires should run straight through from the plug side to the outlet side, while the hot wire will run from the plug prong out to the sensor and then back to the female outlet hot side.  If so, I would call it a series setup.  It's sort of like the old fashioned christmas lights where the wire went from one bulb to the next, and if any bulb died it took out the entire string.  Here the sensor is acting as a switch and turning power on and off to the receptacle side.

In a parallel setup, such as you see in some electronics gear, or in modern christmas lights, all three wires are both passed through to the other side AND branched off to serve as a power feed to some other device or an extension cord outlet.

You need to use the continuity checker on the unplugged unit in order to figure out if it is indeed a series setup like I suggested earlier.

Hope this helps,

Gooserider


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## BrotherBart (Mar 23, 2009)

Ain't gonna be no buzzing out what does what and where. It is a molded plug with an outlet in the back. Everything is nicely encased in hard rubber. Looks like this and the cord runs from the wall to the StoveStat and the blower plugs into the back of the plug sticking out of the wall. And even if I busted the plug apart I still wouldn't know if I was looking at what they call serial or if it was parallel. Obviously one means that there is straight through power to the outlet on the back when it is plugged in, like a sump pump plug, and the other is like the stovestat and the thing at the other end of the cord does the switching.


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## Gooserider (Mar 24, 2009)

No need to take anything apart to buzz out the connections - I could do it in a couple of minutes looking at what is in the picture.  However looking at it, I'd be amazed if it was anything other than the series type setup I described in my earlier post - that plug wouldn't have room for any sort of active electronic switching or other fancy stuff.  As a second hint, how many wires are in that cord coming off the plug, should be two...

Gooserider


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## Tarmsolo60 (Mar 24, 2009)

series like gooserider said in post 2


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## GVA (Mar 24, 2009)

Series on the hot
Parallel on the neutral

on the sump type setup the hot circuit is closed by the float rising
the stove stat when temp switch closes the circuit closes.
The fact that it has a thermal switch breaking the circuit makes it series......


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## BrotherBart (Mar 24, 2009)

Thanks guys. That is what I needed to know.


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