Would this be a real neutral?

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ronaldrc

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This is a way of getting a neutral from a 120 volt circuit,how many would call it a real neutral?

Create-120, 240-with-a-neutral.jpg
 
This is simply a voltage divider in reverse.

I would think that the L1 and nuetral positions would be switched on the primary side but I guess this will work.
 
I have had one in my shop for years it will work and the neutral works fine as a neutral
and balances with equal loads on both sides as long as you don't overload it.

Is not a voltage divider its a autotranformer.

But would you consider the neutral a neutral ? :)
 
Marc

All depends might just have hook the bonding jumper and hook it to the equipment ground ?

Are you sure it is code compliant ?

I need to read the NEC a little and I'm awlfull lazy now days.:)
 
Forget what I said about bonding to Eq. ground that would make a parallel neutral.
The question would be, would we need a ground rod or not? :-?
 
mdshunk said:
No problem. Install a bonding jumper, drive a rod, and you're good to go. Legal too.
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Given that the neutral going to the garage is the same neutral that comes from the house, why would you need to do anything to it?
Just asking.
 
I am pretty sure this would fall under an Auto-Transformer connection.

Line 1 would be required to be the Neutral ??? for the 240V connection ???

450.4 Autotransformers 600 Volts, Nominal, or Less.

also

210.9 Circuits Derived from Autotransformers.
Branch circuits shall not be derived from autotransformers unless the circuit supplied has a grounded conductor that is electrically connected to a grounded conductor of the system supplying the autotransformer.
 
It is an transformer with two windings wired as an autotransformer. Obviously something somebody had lying around.

An autotransformer basically is a voltage divider if you look at it.

No, a voltage divider is resistances in series. A portion of the total voltage applied is developed across each resistance. Each portion can never be more than the applied voltage.


-Hal
 
hbiss said:
It is an transformer with two windings wired as an autotransformer. Obviously something somebody had lying around.

An autotransformer basically is a voltage divider if you look at it.

No, a voltage divider is resistances in series. A portion of the total voltage applied is developed across each resistance. Each portion can never be more than the applied voltage.


-Hal
Click to expand...

If you look at an Autotransformer the applied voltage is usually at the top and bottom of the two resistors in series. The stepped down voltage is then the point between the two resistors in series.

The equation is Vout= Vin * R2 / R1+R2.

However if we apply the source voltage at the point between the two resistors such as this transformer we would be applying Vout and the equation would be represented as Vin= Vout(R1 +R2) / R2 to give us our steped up voltage in this case.

At least thats the way I visualize this transformer working.
 
Goroon said:
I am pretty sure this would fall under an Auto-Transformer connection.
Click to expand...
It would.

Line 1 would be required to be the Neutral ??? for the 240V connection ???
Click to expand...
It would not.

210.9 Circuits Derived from Autotransformers.
Branch circuits shall not be derived from autotransformers unless the circuit supplied has a grounded conductor that is electrically connected to a grounded conductor of the system supplying the autotransformer.
Click to expand...
As shown in the OP schematic, the neutral is continued through to the load.
 
Transformer windings should not be looked at as resistances. A voltage applied to any winding, or part of a winding, develops a specific volts:turns ratio. If the output is taken from a greater number of turns, the voltage is stepped up; if taken from a lesser number of turns, the voltage is stepped down.

If you take any typical 120/277 transformer, like you'd find in egress and exit lights, and apply 120v to the white and black wires, 277v will be developed between the white and orange wires, and likewise, 277v between the white and orange wires would deveop 120v between the white and black wires.
 
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