220 no neutral question rephrased

Specific Inspection Topics Electrical Inspections
#1

greetings…my stubborn inquisitive streak is adament. I don’t understand no neutral in 220. I’ve done my homework and checked every electricity site I can find but all answers only seem to answer (paraphrased) that “thats the way it is” I don’t even mind being considered ignorant if I can get an answer.

My understanding: electricity seeks to work in a circuit…120 utilizes a neutral to complete that circuit back to source (and ground)…220 doesn’t ‘need’ neutral because each pulse uses the off phase of the other side for this purpose and AC back and forth but where is the circuit since the power is only looping back to the hot bars. seems like a closed system…the only thing i can imagine so far is that the earth ground provides the only circuit path which would seem to be to be only half the safety feature desired. (bear with my lack of technical jargon) …then if the earth ground becomes broken there is no circuit at all. now any 220 appliance I touch…I become the one and only connection to earth and therefore fry on the spot. I realize I’m missing something…just want to know what it is.
thanks for all the input I’ve recieved…its appreciated and valuable

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#2

I will try and explain this to you. Let’s start with a question, do you remember my battery analogy from a thread a few weeks ago?

#3

http://www.nojolt.com/Understanding_240_volt_circuits.shtml

#4

hey robert…yes i remember the battery analogy, which I could see the series picture and winding up with 3volts when combining the two 1.5v…did not understand how ‘the connection point represented the neutral’ (I think you said) and neither the one nor two connected batteries do anything till a circuit is completed but ok…Im listening
thanks

#5

The batteries represent a power source, no different than the secondary of a transformer which is providing power to your house. In the battery scenario you have three connection points (either end and the center where the two batteries meet). The transformer secondary is exactly the same, it also has three connection points, the ends of the coil and the center point between the ends which would be your neutral. (In these examples ignore the batteries’ polarity).

In the battery set up if you connect meter across the two ends you will measure 3 volts. Connect the meter across the center meeting point and either end and you’ll measure 1.5 volts.

For the 120/240 volt system it’s exactly the same as the battery setup, if you connect you meter across the two ends you will measure 240 volts. Connect the meter across the center and either end and you’ll measure 120 volts. So a two wire circuit can connect to both “ends” of the transformer secondary and you will have 240 volts. The midway point between the two ends (the neutral) requires no connection to get 240 volts with only two wires.

#6

Very good explanation!

#7

robert…thanks for hanging with me, some things take me ‘baby steps’ to get there…the battery setup doesn’t seem ‘exactly the same…’ to me yet because two batteries hooked in a series still have a -side and a +side on the arrangement…kind of resembling hot and neutral to me, though I know nothing of DC which is probably a whole new ballgame. so you still get no action till some sort of circuit is complete. so far in my understanding a more accurate use of the battery analogy is taking two seperate 1.5 batteries and running a wire from the + side of each to some gizmo to get 3 v it still wont do anything because theres no - wire.
hey thanks…i dont feel too bad since virtually nobody takes this on I feel I’m not asking dumb questions but difficult to answer ones. I even asked an established electrician and he just answered because 220 uses both sides and 120 only uses one…hmmmmm…ok
long as youre willing to keep trying im listening

#8

Wikapedia has a flash graphic that demonstrates it perfect, but you must find the keywords as it was posted 3 years ago.

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#9

The reason I asked if you remembered the example from the old thread is because in that old thread I said to ignore the battery polarity. The reason I like the battery example is becuase you can put two batteries in front of you and visually see what I’m saying. Again since the batteries are DC any comments related to this being the same as a 120/240 volt AC system you would need to ignore the battery polarity.

Also think of the two batteries in series as a power source, the same way that you would think of the three wires coming into your house panel as a source.

Having said that does it make any more sense?

I’m not sure if you’re quoting that electrician exactly but there is no system where you would have 120 volts and 220 volts. For the sake of discussion in a single phase system get used to using 120 and 240 volts.

I’m still here if you want to ask more questions. :smiley:

#10

yes my bad on saying 220…saw that after posting but oops too late. well i dont want to take this to the point of being annoying…i know enough to remove a panel cover and do all I need to as an inspector…and Ive done extensive home wiring for ten years (my own) and still live to tell of it so I guess I have the basics well enough to survive…its just that Im so darn inquisitive I tenaciously pursue detaily things I dont understand.
and I just cant understand (yet…my ‘ah-haaa’ moment will come one way or another) and I just cant understand why each of those two sides of 240 dont insist on going ‘home’ to the ground and theyre happy just to feed back to the hot source…while 120 needs to circuit back to the earth (again pardon the rhetoric) at the risk of appearing dense I can not rest when something like this gets lodged upstairs. I’m thankful for the input and read closely whatever replies I receive.

#11

This might help…

The 120V does not return to ground, it returns to the power companies center tap on the transformer. Yes, this center tap is also connected to the earth ground but does not have to be to operate. Grounding and bonding is another whole subject matter that trips up most all new inspectors.

In the example using the two batteries, it might help to label each end of each battery as plus and minus both since this is basically what they do in an A/C circuit. They change directions during the 60 hertz cycle. A/C waveform’s are another whole lesson.

If you forget the ground and just think about the two hot legs and the center tap you will get it.

The center tap transformer is the whole reason we have safer residential power here vs europe, it allows us to drop the actual 240V supply in half.

#12

The current doesn’t need to “go back to earth” in a 120 volt circuit, it goes back to the utility transformer and just happens to be grounded for other reasons. It will still yield 120 volts even if it’s ungrounded. Again if you think back to the battery example, say the battery is 120 volts, if I measure the voltage at each end it 120 volts, put two batteries in series and each end now measures 240 volts. Grounding plays no role in how the voltage is measured.

#13

Here’s a couple links that may be helpful:
All About Circuits
Hyperphysics

#14

all explanations presented to my inquiries are read carefully and pondered upon, even sites recommended, and its like a dimmer switch is being turned up…not a light bulb over the head like in cartoons…but the switch is going up (ie its moveing towards ahaa moment) maybe my concept of how electricity works in general is skewed.
Mikes concept of ‘how electricity works’…at super basics:
(look beyond any wrong wording here…I don’t care so much about getting terminology correct as understanding the concept)
I’ve always thought, and this concept was buttresed by my ITA elec instructor (and I must have missed ‘the rest of the story’)…that electric energy has one thing in mind and that is to somehow, eventually ‘get home’ which is in the earth where it can dissipate. I’ve been also presented with the analogy of a water filled hose with a pump on each end each pulsing on the others off cycle (AC) this makes sense too…but just leads me back to that darn ? of why the uninsulated neutral guy line on the supply line is not energized but wait…I didnt say that…don’t want to go there yet. So anyway I have this thing in my head that elec is always seeking to get home and looks for the easist path…meaning I can become the short circuit by grabbing the wrong thing and providing that easier path. So If it can be pointed out where that mindset is incorrect…then I will have enough food for thought I believe to sort this thing out. Sure do appreciate all the input…Im ‘getting’ things I have not been able to in the past. You guys rock!!
and hey I hate to sound like a guy sitting on a high stool wearing a dunce cap most other areas I have no problem with but this electric gig is just a sonofagun to me and i love learning.

#15

The red wire acts as the black wire’s neutral for half of the cycle and the black wire acts as the neutral for the red wire for the other half of one complete cycle.

You need to understand this concept on multi wire circuits like kitchen plugs where you only need one neutral wire for two hot wires. In this situation it is critical that the red and black wires are not on the same bus or the single neutral wire will be carrying double the amperage.

#16

Let’s apply this question as to no neutral in the 220 or 240 volt scenario. Realistically, it can be 110-220 or 120-240. We wont go into 208 for now.

Wiring for straight 220 will typically have a hot-hot-ground configuration. Thats it. Two conductors and a ground.

Hot-hot-neutral-ground will be seen (and is proper) in scenarios where 120 volts is needed.

This would be seen in a range, as opposed to an AC Compressor unit. The range would need 240 for the heating elements, and 120 volts for the controls. In this scenario, a neutral is needed.

The AC compressor relies on straight 120 to each leg. This is why you also wont see a convenience receptacle derived from AC power on an exterior. The AC unit needs all 240 volts…

Beyond the hypothetical theory behind all of this, is the need for the practical application of this knowledge.

Also, one cannot automatically assule that 120 on one leg and 120 on the other (measured to ground), will equate to 240 between the legs. It will sometimes add to 208volts, where each leg is 180 degrees out oof phase from the other.

Like I said, lets not get caught in the muck and mire of theory too much. The practical application of knowledge in home inspections is key.

#17

I am not an electrician, so this is my attempt to explain the confusing concept of electrical flow.
The path electricity generally takes is the one of least resistance. You may be that path if the conduit, boxes and devices are not properly grounded (the transformer and poles, etc are grounded) and you become part of that path by touching conduit that has come into contact with bare wire. You may not take a large jolt if you are more resistive (tougher path) then the wires, but if you have moist hands or standing in water, you may take a larger jolt because you become the “easier” path for the electricity to flow through. All of the flow does not especially have to run on one path if it has multiple directions to go, but more will travel through the easiest path.

This is the reason for grounding receptacles, boxes and conduit, the equipment grounding conductor is an “easy” or less resistive path for electricity to flow if it comes in contact with any of these surfaces and carries it to the neutral/grounding buss and then out to the grounding electrode or water service in the ground. It provides a safe and easy path for electricity to flow if it is improperly touching anything outside of the insulation or devices on the wire itself.

This is also why it is crucial to have “tight” connections, screws and posts with wiring, anything loose or broken along the path adds to greater resistance in the safe path of the equipment grounding path and could lead to a person being the easier path. So, electricity flowing on the proper path will either be used and changed to heat, work or light or it can flow back to its source to continue the process again. If it is not flowing on the proper path, then it will flow by any means on the easiest path to ground.

I hope this helps and is my best functional understanding of the concept.

#18

Think of the ground wire as a back-up or emergency neutral wire. If the current gets to a place where it is not intended to be, the ground wire will carry the current away safely and allows the breaker to trip due to the short circuit and over current. Hence the proper name of over current protection device.

#19

Sorry, not correct.

The GEC/rod connection will not typically have low enough resistance to true ground as seen at the power companies transformer neutral to trip a breaker.
Testing has been done and info on message boards about this. Its not an easy or safe test to do since you would have to disconnect the neutral at the house and measure the current flowing through the GEC with a circuit shorted to ground.

Also, where you use the phrase “If the current” it should be " If the voltage" but that still does not make it a correct statement.

Breakers trip when excess current travels through them. It would be rare to trip a breaker with current from a hot to earth ground as defined as the GEC at the house unless it is also connected to a grounded water pipe or neutral that feeds over to a neighbors house.

Grounding and bonding systems are another subject.

The ITA instructor was either taken out of context or he is wrong. No current to ground is needed and would indicate a problem if much at all exists.

Think of it this way:
The current keeps cycling through any activated circuit/device connected through the power company’s transformer. The current simply makes a loop it does not dissipate into any ground. Its the power taken off the circuit that you are paying for but its measured by sensing the amps and converting it into kilowatt hours. The power company generates power at their end and you use it at the house, some is wasted along the way (line losses and transformer losses) as heat dissipation. The voltage is the force that is available and the current is the electron flow due to whatever device is activated. Power (wattage) is voltage times the current. Lookup ohms law.

#20

Actually in a WYE system where you would have 208Y/120 volts the phases are 120° out of phase. {120 * 1.73 = 208}

Maybe some of the confusion here is that Rick used a generic term (grounding wire) to describe something. I think that he actually meant the equipment grounding conductor (EGC) and not the grounding electrode conductor (GEC), maybe he can clarify. Using the proper terminology can be important since the wrong terminology can be very confusing. :wink: