Richard,
I honestly think you do a fine job at explaining it. Basically people need to understand that Electricity is still a learning curve in that we teach it alot around the country and call it " Electrical Theory " and why do we call it that?
Well it is because we are constantly learning everyday more and more about it and many people ( much smarter than me ) spend their whole life trying to understand it…personally I learn something everyday.
Here is some verbiage I got from somewhere…It is VERY detailed to actually go into depth on alternating current and explain the change of direction but it is also important to note that IN that understanding the Grounded Conductor is connected to earth…the ungrounded conductor is NOT…important FACT…and if you think about it ( think about that I mean…really think ) defines why a reverse of the polarity to the touch could be very important if you are grounded…and the ungrounded point you TOUCH is not…
Reversed polarity can be dangerous because many pieces
of equipment will operate properly even though the supply
wires are not connected in the proper order. Traditional
reversed polarity occurs when the black (ungrounded) and
white (grounded) conductors are reversed. A shock hazard
may not exist, but other mechanical hazards can occur. For
example, if an internal fault should occur in the wiring, the
equipment would not stop when the switch is released or
would start as soon as a worker plugs the supply cord into
the improperly wired outlet. This could result in serious
injury.
When the black (ungrounded) and green (grounding)
conductors have been reversed, an extremely dangerous
situation can occur. A metal case covering a piece of
equipment so wired will be “hot.” When a worker picks it up
and touches a conductive surface in the surroundings,
he/she will receive a serious, or even deadly, shock.
When the white (grounded) and green (grounding)
conductors are reversed, a hazard can also exist, even
though this should not actually be called reversed polarity.
In this case the white wire is being used to provide
equipment grounding. Under certain conditions this could
be dangerous.
Ok…lets talk about testers which we have a gazillion times…the testers we use everyday in the form of the " dummy " 3 lite testers get fooled on many things ( bootleg grounds is one that comes to mind rather easy )…in general I don’t see alot of testers fooled about Reverse Polarity versus the bootleg issue…
Now in many of the sure test units if you check the circuit too close to the source you will get a no ground present reading…and i believe this is covered in the handouts I posted online long ago…search for it…I don’t have time to post it…
Here is another nice article on thd subject…I did not have time to fully read it all but appears to be accurate…
16.22) Reverse polarity outlets - safety and other issues
"Our new home has reverse polarity in all of the electrical outlets. The house inspector
didn’t seem to think this was a major problem, and neither did he think it was worth fixing.
Can anyone explain how this might matter for us? The best I understand this is that when
something is plugged in, even when it’s not turned on, there is still a current going through
it–is that true at all, or is that normal? Our biggest concern is our computers, and the possibility
that our surge protectors won’t be effective. If anyone could clear this up, that would be great.
"New as in brand new or new for you?
If it is a totally new home, the builder should have them fixed and you should not sign off on
the house until this is done. While there is no imminent danger, the house inspector was being a
bit too casual for my tastes. It is not a big deal as in should stop you from going through with the
purchase but it really should be fixed. As far as current present when the appliance is off, this is
not quite true.When properly wired, the power switch is the first thing in the circuit so itcuts off
power to all other parts of the internal wiring. With the reversal,it is in the return - the rest of the wiring will be live at all times. Except or servicing, this is really not that big a concern and does not represent anyadditional electricity usage.
Normally (I assume these are 3 prong grounded outlets) you have the following:* Hot - the live conductor - the narrow slot.* Neutral - the return for the current used by the device - the wide slot.* Ground (or safety ground) - the U shaped slot.
Reverse polarity means that Hot and Neutral are interchanged. (any othervariation like an interchange with the ground represents a serious safety hazard and it should be corrected as soon as possible. The outlet should not used until it is).
For most appliances and electronics, this does not really matter. By design, it must not represent a safety hazard.
However, there can be issues - as you are concerned - with surge suppressors and susceptibilityto interference.
In some cases, the metal case of a stereo could be coupled to the Neutral by a small capacitor to bypass radio frequency interference. This will be coupled now to Hot instead. While not asafety hazard, you might feel an almost imperceptible tingle touching such a case.Surge suppressors may or may not be affected (to the extent that they areever effective in any case - unplugging the equipment including modem linesand the like during an electrical storm is really the only sure protection but that is another section). It depends on their design.
Some handle the 3 wires in an identical manner and interchanging them makes no difference.Others deal differently with the Hot and Neutral in which case you may loseany protection you would otherwise have.My advice:
Use a properly wired outlet for your computer to be doubly sure.I t is not an emergency but I consider proper wiring to be very desirable. Here is another example:
"I was checking some outlets in my apartment. As I recall, the narrow prong should be hot, i.e., there should be 120 V
between it and the wide prong or the ground prong. The wide prong should be neutral, i.e., it should show no voltage relative to the ground prong. Well, it appears that the Neutral and Hot wires are reversed in some outlets. In others, they are correct.
"Well, there should be very little voltage although it may not be 0. Reversed polarity outlets are not unusual even in new construction.Reversed H and N is not usually dangerous as appliances must be designedso that no user accessible parts are connected to either H or N - eventhose with polarized plugs.
Think of all the times people use such appliancesin old unpolarized outlets or with unpolarized extensions cords. (There areexceptions like electric ranges where there may be no separate safety groundconductor but I assume you are talking about branch circuits, not permanentlywired-in appliances.)"In still others, I get some voltage between ground and either the wide or narrow prong. Ack.
Should I worry? Should I do more than worry? "You should, of course, measure full line voltage between the H and G. The safety ground, G, does not normally carry any current but is at the same or nearly the same potential as N.The voltage between G and (actual) N if quite low - a couple volts or less - is probably just due to the the voltage drop in the current carrying N wire.
Turnoff everything on this branch circuit and it should go away. However, there could also be a bad (high resistance connection) somewhere in the N circuit.If the voltage reads high to either H or N - say, 50 volts - and you are measuring with a high impedance multimeter, this is probably just due to an open ground: a three prong outlet was installed without connecting the ground(in violation of Code unless on a GFCI) and this leakage is just due toinductive/capacitive pickup from other wires.
Full line voltage on the G conductor relative to an earth ground (like acopper cold water pipe) would represent a serious shock hazard to be correctedas soon as possible - the appliance or outlet should not be used untilthe repair is made. While unlikely, for anyone to screw up this badly, itcould happen if someone connected the green or copper wire, or green screwto H instead of G.In any case, it would be a good idea to correct the H-N reversals and determineif the voltage on the G is an actual problem.
