Voltages in Power Lines

Most recent answer: 02/25/2015

Q:
Hello, I am an inspector contracted by a large utility company in Missouri. I have a question that is fairly specific but I could only imagine if I had a better understanding of electricity it would be quite simple. I assure you I would not be writing if this question has a huge bearing on our procedure man hours and by proxy money. My question has to do transformers and more specifically the power they produce. You see when any power riser (pipe that runs electricity underground) carrying greater than 300 volts is broken it is deemed an emergency to public. an immediate work order must be typed up and a crew sent to repair it within a specified time. From my understanding the majority of transformers produce 220 volts. Below the protocol for an emergency. The confusion is here, if a transformer has two 110volt hot wires running out of it and each of them split into 4 wires before running into the riser does that riser have a total of 440 volts? If u have any questions please ask. If you know any place I could find the answer or info on the topic please let me know. I sincerely appreciate any info on this topic more than u will ever know. Thank you, wayne eiting
- wayne eiting (age 26)
saint charles, missouri, usa
A:

I'm not 100% sure I understand your description correctly, but one thing is sure. The voltage differences between the lines coming out of the transformer are not changed when the line is then split into several lines. For example, say there are two lines from the transformer, each at 110 Vac from ground and 180° out of phase with each other, so at 220 Vac from one line to the other. If each of those lines branches into some sub-lines, each pair will have a voltage of  0 Vac or 220 Vac depending on if they come from the same or different lines. All will be at 110 Vac from ground.

One way you can think of this is that voltage is like a height. Four separate hills each 100 m high still only reach 100 m height.

Mike W.


(published on 02/25/2015)

Follow-Up #1: voltage and pressure

Q:
if I have a single 110 volt line and I split it into 2 separate 110 volt lines do them lines now have a total voltage of 220 volts? my confusion is that from what I understand volts are comparable to pressure. if I split the pressure of one hose how would it double? from my understanding the pressure(voltage)remains the same. hypothetically could u just split a 110v line to power 220 volt appliance by simply splitting it before attaching? could I not just continually double voltages total voltage by splitting lines?
- Wayne (age 26)
A:

Yes, voltage is very much like pressure. You're absolutely right that splitting a 110 V line into several lines won't raise the voltage. I think that's exactly what we said above.

Mike W.


(published on 02/26/2015)