just how dangerous is the neutral wire?

| Like the man says...if individual neutral at the neutral bus | is not connected well that neutral as you say will have | current flow available to it as defined by ohms law and the | resistance if the connected 'upstream' load..and it is | dangerous. | | IF the individual neutral is well connected BUT the neutral | back to the transform is not well connected you have the same | problem. | | AND if there is an unbalanced load from from Line 1, 2 or 3 | that flows into the neutral then that neutral will read | *current flow to its ground which as you know will be | dangerous. | | So why doesnt the NEC require the neutrals to be protected? | Because it is not practically possible in these scenario's... | the flows are too variable. and protecting individual | neutrals would be entirely redundant. | | So what does one do? He can choose to not put his tongue | onto the neutral while standing in a puddle of water... that | would work.

Or he can choose to use appliances that don't have a need to have a neutral connected, which allows not running the neutral to the load at all. Loads that have a NEMA 6-XX plug are like that. No reason we can't have more of them.

It might be helpful to have some NEMA 6-15R and 6-20R GFCI receptacles.

| When you figure out how neutrals can be wired to always be in | balance with multi phase feeds, or how to protect users from | current in the neutrals as it varies let the NEC folks know | you could get rich.

A neutral that isn't there ensures the two hots are in balance. People don't get rich by showing the obvious.

| Currently thier practice though is to size the neutrals to the | transformers sufficiently large to carry any possible | imbalance or bolted dead short at full amperage long enough to | trip the over current devices at the transformer or main | breaker panel at the user end... but not to protect the user | from current if he touches the neutral. | | after all, there is no protection provide to the user if he | touches one of the hot lines either... those breakers are | there ONLY to protect the wiring to prevent a fire... its is | totally insufficient to protect from most electrocutions that | occur over a much longer time frame and lower amperage than | the over current device rating. | | Its the GFI that protects users... and those are available on | the line side as you know... your question then is why not on | the neutral?

Yes, that is the question. But keep in mind that GFCI receptacles actually do disconnect the neutral. That is certainly an extra cost, and manufacturers don't tend to add extras they can't use as a marketable advantage (they sure aren't marketing such a feature) so why are they doing this?

| I think that could be done actually...you would put a GFI on | the neutral wired appropriately with a good bond to | ground..have it operate a magnetic contactor in the service | feed, and kill the main feeds if the there was a fault from | the grounded neutral to ground.

The neutral wire already flows theough the current sensor with the hot wires. Just add the ability to disconnect it, and do it in compliance with NEC (ensure that the hots disconnect not later than the neutral).

| Why dont they do that? Because electricity takes the path of | least resistance and if the neutral is already bonded, you | touching it even as it carries current will not take the | entire potential to ground through your body because your body | has more resistance that direct ground only a fraction of the | potential, lets say 2% as a wild guess in most cases, will go | through you.

But they do disconnect the neutral, as I described earlier.

Futher, 20 milliamps of current is not going to damage a 14 AWG wire, but it can kill some humans.

| If the flow through neutral is 40 amps, thats 2 amps... enough | to fry your eyeballs if you touch your tongue to the neutral | while standing in water.

The human won't get the 2 amps. But they can easily get several milliamps, or tens to hundreds if the neutral is open upstream.

| So the lesson then is obvious. Neutrals are hazardous, just | not real hazardous unless one does something stupid.

Or if something breaks, like water getting into an appliance.

Why do we need GFCI in a bathroom? Why not just not do a stupid like dipping the hair dryer in the basin? Well, accidents happen that people have no control over.

Why GFCI in a kitchen? Water related accidents.

Why GFCI in the laundry room? Water related accidents.

Why GFCI in and around a Jacuzzi? Water related accidents.

| the NEC is not intended to protect from that problem as much | as it is to prevent fires believe it or not...the NEC is part | of the fire code...

If that is so, then why does it have all these GFCI requirements?

A great many of the NEC requirements have nothing to do with fire hazards. It's a fire AND SAFETY code.

My intentions is to gather evidence and build arguments to recommend that the NEC be revised in a future edition to require that all circuits in what are considered wet areas, or subject to water in a reasonable distance, be fully GFCI protected regardless of voltage or amperage. And by fully I mean disconnect the neutral in all cases.

|> | The 120 volt GFCIs do open both sides (I took one apart just for fun to |> | determine this.) The reason is to protect folks from improper | installation |> | (revering hot and neutral.) |>

|> You are speaking of receptacles, not breakers, right? | | Right! | | I would be quite surprised is the breaker type GFCI disconnected the white | wire. It's bad enough that switch loops end up with "hot" white wires. | But a GFCI breaking the white wire in the panel could result in a HOT white | wire where one would least expect it.

There are breakers available that switch the neutral. They certainly can do this. Such breakers have a pigtail just like GFCI and AFCI. And these breakers must have the reliability to ensure they they do not create a new hazard by making sure the contacts are all disconnected so at no time the hots alone are connected. Now all that needs to be done is to combine the capability of SWN breakers with GFCI breakers (or in some cases also AFCI).

| Just how would you have a hot white wire? What bazaar failure mode do | you anticipate for this to occur? If both of the ungrounded current | carrying conductors are open were will the voltage for this condition | come from?

Google for "open neutral".

| We always 'mark' such white wires when needed (mostly three-way switch | installations). Of course, it isn't absolutely required by code, but it | does mention it. It sure makes me feel better when I open up a switch box | and find a black wire on one side, and a white wire with black marking on | the other.

Of course if you are going to install a "French 3-way", the wire from each of the 2 switches to the light will have to be marked both white and black. Then the rule is, don't stick your finger in the light socket even if it is switched off.

| I am rusty on that code but I think the neutral has to be | broken with the line power on gas pumps...i could be wrong on | that though. It is in the NEC though.

I remember seeing something about it. I wasn't planning on having any gas pumps at home or in the computer center, so I skipped that part.

| I think its to prevent any small amount of arcing that could | cause an explosion... not because the there is typcially | enough current to ground through a human to cause any real | damage... and..

Separate issue. They don't GFCI protect the hot wires. Whether or not that would help I cannot say.

| Unless you "make" the neutral first and "break" it last then disconnecting | neutral can cause unexpected voltages in unexpected places.

But they do that with SWN type breakers. That also has to be done with

3 and 4 pole transfer switches.

Personally, I'd prefer just outlawing 3-wire appliances (4-wire for three phase). If it takes 2 hot wires (3 for three phase), then power everything from that and don't access the neutral. The technology does exist to run motors (in clothes dryers) on 240 volts, and to power electronics (in a modern stove) on 240 volts. Obviously they have to do this in Australia, Europe, and many other places in the world. Most computer switching power supplies handle 100 to 240 volts. Small DC power supplies for integrated electronics can at least be made in 220 to 240 volt input versions. So I see no reason any home appliance can't be made to run on 2-wire just as cheap as 3-wire.

| I did not consider the test button in my post. There indeed is a resistor | connected to the test button. I have also found that a capacitor of 0.25?F | from hot to ground will trip GFIC. That has an impedance of about 10K with a | consequent flow of about 12mA. I think that filtering capacitors in surge | protectors and other devices often cause "unexplained" GFCI trips.

And thus, are to a slight degree, putting some voltage on the grounding wire.

| And what problem would that be? The GFCI's internal circuitry (except for | the neutral-ground excitation coil) is deenergized when the hot is opened. | Now you have only the voltage drop thru the neutral from the main panel to | the sub panel. At most this is ~3.5VAC. With a 'bolted fault' between | neutral and EGC, the full load of the sub panel would split 50-50 between | the two conductors and the resulting voltage above the main panel's ground | bus would be ~1.75VAC. Hardly any sort of problem at all.

Then explain why my 2m radio transmitter caused a GFCI receptacle to energize the tripping coil continuously?

I've heard 2 arguments. One is the unit was wired backwards. The other is that it needs to be energzied on the line side to make sure the trip action sustains enough power to complete.

| Exactly. That is what I was saying. And this voltage is at most about 3.5 | VAC in a fully loaded, but properly sized sub panel fed from 100ft of wire | from the main panel. Are you suggesting that 3.5 VAC is lethal to some | folks?? Why??

A combination of heart problems and kidney problems can do this to people.

| Nevertheless, a GFCI can trip properly even with no ground wire connected to | it. With no ground wire to the GFCI, taking the neutral downstream of the | GFCI to a ground that leads back to the service panel will trip the GFCI.

However, connecting the downstream neutral to a downstream ground that originates at the GFCI (e.g. does not go back to the panel) will NOT trip the GFCI. Hence, the code requirement that ungrounded GFCI not be allowed to pass along a ground wire to downstream receptacles.

| Okay so you keep on installing GFCI's without a ground like you suggest, | I'll keep doing it my way Properly Grounded & with Care.

Properly grounded is better for grounding reasons. But where lack of ground exists in the wiring, there still remains the chance of being the path to ground yourself. Touch a hot wire (maybe even a neutral wire), and some OTHER ground source like a water faucet, and the shock hazard exists. The GFCI on the UNgrounded circuit WILL detect that current flow that isn't coming back on the other wire, despite having no grounding wire. Lack of a grounding wire in a GFCI makes it harder to test. But they accomplish that with the sneaky method of going between the upstream and downstream sides of the current transformer that senses the current balance.

| | Dry-ish feet on a dry floor?

Yes, dry feet, dry floor. I'm sure there was more impedance than just what my body provided. That's why I say "fair portion". I don't know just how much, but it was enough of a jolt to make damn sure that never happens again.

Wet feet, wet floor, could have been worse. Of course some people might say it would be better to not have my ranting and raving here. :-)

Well said.........

This whole thread is about the dumbest one I've seen yet.

Whether the neutral is hot or not is totally irrelevant. The neutral is subject to the same insulation requirements as any "hot conductor." Even if the neutral becomes live, current code requirements prohibit the neutral from being exposed or (in almost all cases) used as a equipment grounding conductor.

Why should a live white wire be any more or less of a hazard than a live black wire?

Where, in a code installation, can a person contact a neutral conductor? Exactly the same places one can contact a phase conductor! And if you start "what ifs" about non-code installations, what effect will changes to the code bring about?

Sometimes, people looking for a new way are really stuck because they don't understand the old way!

It's not unusual for some kind of network be placed between BOTH sides of the power connectoin and the chassis (local ground). The network is oven a relatively high value resistor and a small cap. For RF purposes, you radio uses "ground" and both supply wires. If the resistors aren't big enough or the caps no small enough then it can cause enough current to flow to be a detectable ground fault. Since the "neutral" GF detection often uses double line frequency sensing (it injects a signal) the caps in the network will pass more juice.

Note the most PC power supplies have such networks installed.

Anyway, GFCIs aren't for every load.

Gad! You don't have much of an imagination.

IF you have something protected by a GFCI and a HOT leader from another circuit crosses the NEUTRAL "protected" by a GFCI, the CFCI will detect the ground fault and will trip and it will likely trip BEFORE the breaker on the other circuit. Note that the fault has NOT be properly cleared as you have a "hot" HOT crossed with a now isolated NEUTRAL. Your "neutral" wire now has 120 volts.

So?

If you think it is a "dumb threat" just drop out.

Because MOST of the time wire wires are safer than black wires. Just as, for e3xample, the threaded portion of a lamp sockets is safer than the contact at the bottom. And that's why there are polarized two prong plugs and outlets.

How about when screwing in a lamp?

You truly lack imagination.

ROTFLMAO!!!!

That's a good one!!

daestrom

| the gfci installation went well., I tested it before closing it up and | the Test/Reset buttons DID work as JG & Charles mentioned, but this is | my point, Neutral will not be the likely point of contact in a common | Body to short circuit incident and I had doubts how much is normal | function without the earth/ground applied.

It's not necessary to actuall form a circuit with real ground to do a test. The possible failure modes in a GFCI device, such as the CT coil being open or shorted, can still be tested for using a sneak around the CT by part of the circuit. We only need to be sure the CT all the way to the contact release and open is functional. The test circuit used accomplishes that without an actual ground needed.

| on that note: Most Noticebly my GFCI Tester (again in this new test) | Failed to make a trip without the Box ground reference, which brings up | the full functional capacity of the gfci doubtful.

Being an external device, it doesn't have the ability to sneak around the CT as the internal tester does. So for this device, yes, you need to get an external ground source if the ground wire isn't available on the circuit itself.

The test button on a GFCI receptacle is there for the monthly tests users are supposed to do. If the circuit snaps open when the test button is pressed, the device is almost certainly going to catch the next ground fault. Sure, it could break 5 minutes from now and let someone die 10 minutes later on. The point is, THIS TEST works even on an ungrounded circuit. It is NOT a test to see if the ground is good (a test which would be inapplicable on a non-grounded circuit).

| How can you get 'upwards of 120 volts on the neutral' if the hot lead is | opened by the GFCI? The original question was whether all GFCI's should | open the hot *and* neutral, whereas some breaker-style GFCI's only open the | 'hot'.

Open (or flaky) neutral up stream. Some large 120 volt load (motor) on the same branch sharing the neutral (like in a subpanel).

While I will be trying my best to be sure all loads in my house will be

2-wire type loads, in cases where 3-wire loads can't be avoided and do present mroe significant risk (a stove is less likely perhaps, and a jacuzzi is more likely), an isolation transformer could avoid this (and some significant added cost).

| Unless you have a GFCI off of a sub-panel, and the sub-panel feeds other | circuits, and the sub-panel to main panel neutral opens? On top of that the | person has to come in contact with the neutral fed from the sub-panel even | after the sub-panel's GFCI has opened the 'hot' to the hot-tub. How many | simultaneous faults is this, three?

Depends. If I do get a Jacuzzi and do put it behind the detached garage, and don't want to spring for an isolation transformer, I could run the circuit for it directly from the main instead of the sub.

| Granted, if we postulate enough things wrong/faults, anything can happen. | But gee, should I start wearing a hard-hat to bed in case of meteor strikes?

Funny you should say that. But that was 10 years ago. But it did knock out a chunk of the bedroom ceiling.

| Phils what ifs remind me of the material safety data sheet that was | provided for the hand cleaner that was ordered for our fire house. The | MSDS recommended that users ware eye protection, a protective apron, | and; wait for it; gloves while using the product.

You just _know_ that was written by a lawyer :-)