just how dangerous is the neutral wire?

I believe that much of the hazards around the neutral have been eliminated by the separate grounding conductor. In years past, many appliances and such had the *frame* tied to the neutral. This became quite dangerous whenever the neutral developed a problem (such as an open). Old tube radios often had one wire from the outlet tied to the frame/chassis. Lose a knob on the front and touch the metal shaft and you could be in for a surprise.

Newer requirements have the frame completely isolated from the electrical circuit. This goes a long way in minimizing any risk associated with the neutral opening since you still can't easily become part of the circuit.

Well, some may, but I don't feel completely safe anytime I work on wiring near water. Just sort of an ingrained fear I guess. But it helps keep me alive :-)

A neutral that goes back to the panel and is not part of a multi-wire circuit cannot present a hazard when both 'hot' wires are deenergized. It can only be a risk when a hot lead is powered (and the return to the panel is poor/broken). Once the two hot leads are opened, I cannot see how a neutral can present any hazard. (unless it is improperly shared with another circuit). I believe this is why 2-pole GFCI's are made this way. There is no reason for more protection (paranoia??)

daestrom

I saw a guy open up a neutral from a 50 amp circuit of 120v AC fluorescent lights and got nailed like he touched the hot. Dropped him to the ground in a heart beat. We took him to the horsepistol just to be safe.

The neutral carries all of the imbalanced current in the circuit. intentionally grounded

I treat the neutral just like the hot.

As to your questions NO and NO

I know of no small device that would disconnect the neutral. Besides the NEC section 240-22 of my 1999 code book "no overcurrent device shall be connected in series with any conductor that is intentionally grounded." note 1 goes on to say unless the device opens all of the conductors including the grounded conductor and is designed so that no pole can operate separately. Pretty sure your not going to fit this into a outlet box in your home. A 2 pole transfer switch comes to mind.

gfci are ground fault circuit interrupters, not grounded conductor fault circuit interrupters

That is done by installing a separate detection circuit to control a three pole contactor or shunt trip circuit breaker and it is not cheap.

-- Tom H

clearly the conditions must be defined to answer this question. the total resistance of the neutral and the total current going through it must be known OR measure the voltage at the point in question in reference to the nearest earth ground.

Clearly it is a big hazard if it becomes

referenced to what? disconnecting the neutral (of a branch circuit) is the same as opening a switch.

its usually "safe" enough to touch provided you are not touching HOT at the same time.

no, nor would i feel safe pointing an unloaded gun at my own head. i would however work on it after disconnecting the breaker and checking it with a meter. a prudent electrician uses insulated tools and takes no unnecessary risks.

no, i might trip on it

once the hot is broken no current flows therfore no voltage is built up accross the restance.

the kind of problem you are worried about did happen to me once... a long time back. i plugged some equipment into a church and got zapped by touching 2 microphone stands at the same time. what make it memorable was their were 2000 people in the pews and about a dozen armed bodyguards watching while i was trying to pretend nothing happened. i discover about 50 volts on the neutral referenced to ground. i plugged into a different outlet, plugged into a different outlet. problem solved.... notified church official of bad circuit. i believe this was a 2 part problem: faulty wiring in the church and an issue with one piece of my equipment.

however this is rare... it hasn't happened again to me in 20 years.

I bet the problem was that the only grounding of the chassis was incidental via the microphones. Lots of audio stuff doesn't have grounding plugs because hum is produced on the lines.

LIkely and "bad" outlet was served from another phase or by the "other" side of the three wire service.

|> Clearly there is some level of hazard in the neutral wire. |> But just how much? Clearly it is a big hazard if it becomes |> disconnected from its source, and the imbalance between the |> phases is now a voltage on that wire, energizing everything |> that is connected to it (as was the common case decades ago). |>

|> But what I'd really like to know is how safe is it in normal |> connections where it is properly connected, but may be run |> some distance from where it is bonded to ground, possibly via |> a subpanel where other circuits could contribute some voltage |> to it when running out of balance. | | I believe that much of the hazards around the neutral have been eliminated | by the separate grounding conductor. In years past, many appliances and | such had the *frame* tied to the neutral. This became quite dangerous | whenever the neutral developed a problem (such as an open). Old tube radios | often had one wire from the outlet tied to the frame/chassis. Lose a knob | on the front and touch the metal shaft and you could be in for a surprise.

So explain to me how the neutral wire itself is no longer a hazard due to the fact that the grounding wire now exists? Are you willing to touch the neutral wire to your tongue while standing barefoot on wet concrete just becuase a grounding wire exists?

I think you completely misunderstand my statement.

| Newer requirements have the frame completely isolated from the electrical | circuit. This goes a long way in minimizing any risk associated with the | neutral opening since you still can't easily become part of the circuit.

I'm not asking if equipment frames are safe. I know they are safer since they connect to the grounding wire instead of the neutral wire. My question is how safe is that NEUTRAL WIRE. The fact that we do connect equipment frames to the grounding wire tells be the neutral wire is a hazard, and as such it SHOULD BE DISCONNECTED when a circuit is disconnected, especially in wet situations.

|> Q: Would you feel safe grabbing a neutral (presume you are |> absolutely positive it is not a hot wire) while standing in |> bare feet on a wet concrete slab? |>

|> Q: Would you feel safe sitting in a tub with the neutral wire |> either within reach, or dangling into the tub itself? |>

| | Well, some may, but I don't feel completely safe anytime I work on wiring | near water. Just sort of an ingrained fear I guess. But it helps keep me | alive :-)

Same for me.

|> Here's where I'm going with this. Certain situations require |> ground fault circuit interruptor protection to prevent shock |> on a ground fault path. These are generally "wet" situations |> such as the electrical systems of a hot tub of jacuzzi. The |> idea is if something goes wrong and a path to the water is |> set up, a small leakage current will interrupt the circuit. |> But the issue is that in the case of 240 volt loads, GFCI is |> done via a 2-pole circuit breaker. The neutral runs through |> the breaker to be part of the leakage measurement, but it is |> not disconnected when the breaker is tripped off. There are |> such things as a "switched neutral" breaker for places where |> a neutral voltage is recognized as a danger, but these are |> not GFCI breakers. | | A neutral that goes back to the panel and is not part of a multi-wire | circuit cannot present a hazard when both 'hot' wires are deenergized. It | can only be a risk when a hot lead is powered (and the return to the panel | is poor/broken). Once the two hot leads are opened, I cannot see how a | neutral can present any hazard. (unless it is improperly shared with | another circuit). I believe this is why 2-pole GFCI's are made this way. | There is no reason for more protection (paranoia??)

You have 120/240 volt service into your house. From the house you run a

100 amp subpanel to the detached garage. On the back of the detached garage you have deck with an outdoor hot tub. The equipment powering said tub is connected through a 50 amp 2-pole GFCI breaker, connected to the garage subpanel, connected to the house service panel. Someone is using some heavy duty 120 volt equipment in the shop in the garage. How many volts will you read between the neutral and the ground? I think the answer will be whatever the voltage drop is between the garage subpanel and the house service panel for the current being drawn for whatever wire gauge is installed. Whatever that is, you'll still have that voltage at the hot tub even if the GFCI trips due to some malfunction. Tell me how hazardous you think that is. And if you say it's nothing to worry about, then why not just connect everything to the neutral like used to be done.

| I saw a guy open up a neutral from a 50 amp circuit of 120v AC fluorescent | lights and got nailed like he touched the hot. Dropped him to the ground in | a heart beat. We took him to the horsepistol just to be safe.

Considering he was probably in series between line and load, I'd say he got the full jolt. Good thing it wasn't 277 or 347 volts.

| The neutral carries all of the imbalanced current in the circuit. | intentionally grounded | | I treat the neutral just like the hot. | | As to your questions NO and NO | | I know of no small device that would disconnect the neutral. Besides the NEC | section 240-22 of my 1999 code book "no overcurrent device shall be | connected in series with any conductor that is intentionally grounded." | note 1 goes on to say unless the device opens all of the conductors | including the grounded conductor and is designed so that no pole can operate | separately. Pretty sure your not going to fit this into a outlet box in | your home. A 2 pole transfer switch comes to mind.

Seems that 2005 allows it. It specifically requires that such disconnects of the neutral not take place before the hot wires, and reverse for making the connection.

| gfci are ground fault circuit interrupters, not grounded conductor fault | circuit interrupters

My whole point is, the neutral _is_ a hazard, and _remains_ a hazard even after the circuit _appears_ to be disconnected when the neutral is not one of the disconnected wires.

|> Where can one find a GFCI protection device that disconnects |> both hot phase wires and the neutral at the same time? | | That is done by installing a separate detection circuit to control a | three pole contactor or shunt trip circuit breaker and it is not cheap.

So, the average home hot tub is a hazard waiting for a tragedy.

|> Clearly there is some level of hazard in the neutral wire. |> But just how much? | | clearly the conditions must be defined to answer this question. the total | resistance of the neutral and the total current going through it must be | known OR measure the voltage at the point in question in reference to the | nearest earth ground.

It's obviously enough to require a separate grounding wire.

| Clearly it is a big hazard if it becomes |> disconnected from its source, and the imbalance between the |> phases is now a voltage on that wire, energizing everything |> that is connected to it (as was the common case decades ago). |>

| | referenced to what? disconnecting the neutral (of a branch circuit) is the | same as opening a switch.

But there remains a voltage on the circuit, relative to ground, if not all the current carrying conductors are disconnected.

|> But what I'd really like to know is how safe is it in normal |> connections where it is properly connected, but may be run |> some distance from where it is bonded to ground, possibly via |> a subpanel where other circuits could contribute some voltage |> to it when running out of balance. |>

| | its usually "safe" enough to touch provided you are not touching HOT at the | same time.

Define "usually". It must not be safe enough for the code writers that decided we now must have a separate ground wire everywhere.

|> Q: Would you feel safe grabbing a neutral (presume you are |> absolutely positive it is not a hot wire) while standing in |> bare feet on a wet concrete slab? |>

| no, nor would i feel safe pointing an unloaded gun at my own head. i would | however work on it after disconnecting the breaker and checking it with a | meter. a prudent electrician uses insulated tools and takes no unnecessary | risks.

Is there any difference in how you would handle the neutral vs. the grounding wire?

|> Here's where I'm going with this. Certain situations require |> ground fault circuit interruptor protection to prevent shock |> on a ground fault path. These are generally "wet" situations |> such as the electrical systems of a hot tub of jacuzzi. The |> idea is if something goes wrong and a path to the water is |> set up, a small leakage current will interrupt the circuit. |> But the issue is that in the case of 240 volt loads, GFCI is |> done via a 2-pole circuit breaker. The neutral runs through |> the breaker to be part of the leakage measurement, but it is |> not disconnected when the breaker is tripped off. There are |> such things as a "switched neutral" breaker for places where |> a neutral voltage is recognized as a danger, but these are |> not GFCI breakers. |>

| | once the hot is broken no current flows therfore no voltage is built up | accross the restance.

No voltage between the neutral wire and the ground?

|> So basically, this GFCI protection does not disconnect the |> neutral wire. I'm told that most GFCI receptacles for 120 |> volts do disconnect the neutral. |>

|> Where can one find a GFCI protection device that disconnects |> both hot phase wires and the neutral at the same time? |>

| | the kind of problem you are worried about did happen to me once... a long | time back. i plugged some equipment into a church and got zapped by | touching 2 microphone stands at the same time. what make it memorable was | their were 2000 people in the pews and about a dozen armed bodyguards | watching while i was trying to pretend nothing happened. i discover about 50 | volts on the neutral referenced to ground. i plugged into a different | outlet, plugged into a different outlet. problem solved.... notified church | official of bad circuit. | i believe this was a 2 part problem: faulty wiring in the church and an | issue with one piece of my equipment. | | however this is rare... it hasn't happened again to me in 20 years.

A neutral can have a few volts representing the attempt to find another path back to the source, when an imbalance in current exists. Hazards like this are, I believe, one of the reasons a separate grounding wire is required ... to avoid connecting equipment frames to those few volts.

Then when something does go wrong, it only takes one such thing to put the full voltage on the neutral.

| I bet the problem was that the only grounding of the chassis was incidental | via the microphones. Lots of audio stuff doesn't have grounding plugs | because hum is produced on the lines. | | LIkely and "bad" outlet was served from another phase or by the "other" side | of the three wire service.

So as much as 240 volts could be present between microphones.

Ironically, the hum problem can be eliminated, or greatly reduced, while having a grounded plug and everything properly grounded to it, by connecting to 240 volts instead of 120 volts. The alternative is to use a 60/120 volt system like is created by these products:

No I don't feel safe touching the neutral. For one thing, even with the main breaker of my house off, disconnecting both hots, a current of several hundred milliamps still flows down the service neutral from the utility, to the box then out the ground. If the ground became open, the neutral would raise to some potential (perhaps a few volts in this case, but it could be worse). John

Why? If all the "hots" are disconnected, there is no current flow in the neutal and it will be a "cold" as any ground. And since any REAL switch will open one conductor slightly before another, you are more likely to get a 120 volt "glitch" on the neutral if you switch it than if you just leave it connected.

The various remarks about putting one's tongue on the neutral are just plain silly. Practical people don't want to touch ANY thing of metal when working around electricity except for the special case of where they want to ensure they haven't picked up a static charge that might "zap" some silicon.

If you MUST tough metal you touch "ground" first, then neutral and you just DON'T touch hot.

Not at all.

It is safer to leave the neutral connected. If you attempt to disconnect the neutral in a three wire circuit and the neutral is opened slightly BEFORE one of the "hots" then the neutral will, for an instant, have 120 volts.

A functional neutral will have MAYBE 1 or 2 volts voltage compared to ground during normal operation. During a HARD fault, it will have up to 60 volts until the fault is cleared (and if it is a GROUND fault the local "ground" might have an every HIGHER voltage relative to "true ground" since the neutral is usually a heavier conductor than the ground wire.

The three wire stove and clothes dryer circuits (even with the motor running on 120) are perfectly safe.

Obviously, you have to do what the local law and the code require but there is nothing dangerous about the three wire (neutral bonded to the chassis of the appliance) connection.

For every "war story" you come up with that makes the 3 wire circuit look back I can came up with a more likely "story" making the 4 wire circuit look bad.

Dangerous is as Dangerous does ....

If you disconnect a device in a circuit with other devices in tandem the neutral will carry a full voltage load back to the panel, hence you will get a Hefty Shock if you ground yourself in any way while touching that Neutral Lead..... just as if it were a Hot Lead... simply; something like taking the white conductor off a pigtail lamp that has the black conductor spliced to the Hot lead, then holding on to the neutral & grabbing the white lead to the pigtail }:-o you'd complete the circuit.

I'd say it's as Dangerous as can be

I rarely fool around with electrical systems wiring, but, if i got a hold of a Neutral Conductor from the panel with nothing else on it, just a straight run from the Neutral Bar and was barefooted on concrete or in water, if the potential difference across that Neutral to Earth is Greater than 0 Amps lets say 1 Amp I'd get a good shock as well., as a matter of fact if I recall correctly 1 Amp to wet ground could kill.

That's Quite Dangerous

You've got to know what you're doing at all times, and if you're not sure, isolate, investigate and test and investigate & test some more before you make your move on a lead [eyes on always].....That electrician helper you mentioned that got knocked down shocked was just careless, inexperienced, or too sure of himself in a wrong way....happens to the best of us at times a pretty girl walks by, fatigue after the 20th consecutive splice;) I always keep " *** Caution

*** " lit up in my mind while working on live circuits.

They always recommend you Shut Off All Power to any Targeted Circuits before working on them, the theory is: under those conditions Neither Conductor shouldn't present any Real Danger ......

In retrospect: Poorly applied skills & a sluggish mind are more dangerous than a Neutral.

in article snipped-for-privacy@news4.newsguy.com, snipped-for-privacy@ipal.net at snipped-for-privacy@ipal.net wrote on 2/26/05 5:48 AM:

Considering all the crappy wiring I have seen, I would not tempt fate by assuming th wiring was done competently even if it were done by a competent electrician.

In my son's case, a home he bought recently was "upgraded" by installing grounded recepticles near a bathtub. The problem was that there was no ground wire available to connect to the ground.

Bill

if things have gone so badly that there is dangerous voltage on the neutral wire that same voltage will probably be on the ground wire too... referenced to earth.

are we making an assumption that there are additional loads on the same circuit as the jacuzzi? it not a great idea.

usually: the process of troubleshooting and repairing standard residential and commercial branch circuits

thinking about it.... not really. is this a trick question? :)

ok worst case scenario.... im standing naked in grounded metal Jacuzzi (with the Swedish bikini teem) holding a 12 gage neutral wire (white with bare ends) when a bolt of lightning hits the pole transformer. common mode DC flows vaporizing the WH meter, melting the ground rod then seeking any and all paths to ground. i miraculously survive and the bikini teem nurses me back to health. if it happens about 5 more times i then win the super lotto. now i have forgotten what point i was going to make.... but i had fun fantasizing about the bikini team and a Jacuzzi.

nope... assuming all is well at the main panal.its 'cold'.

i'd classify it more as a nuisance than a hazard... you can work all day with bare hands on active 6 V 12 V or 24 Vac circuits and never feel a thing.

and then if all goes well the breaker trips or the fuse blows

|> I'm not asking if equipment frames are safe. I know they are safer since |> they connect to the grounding wire instead of the neutral wire. My | question |> is how safe is that NEUTRAL WIRE. The fact that we do connect equipment |> frames to the grounding wire tells be the neutral wire is a hazard, and as |> such it SHOULD BE DISCONNECTED when a circuit is disconnected, especially |> in wet situations. | | Why? If all the "hots" are disconnected, there is no current flow in the | neutal and it will be a "cold" as any ground. And since any REAL switch | will open one conductor slightly before another, you are more likely to get | a 120 volt "glitch" on the neutral if you switch it than if you just leave | it connected.

If it is that safe, then we didn't need to add all these grounding wires to receptacles, as the neutral would be sufficient. But someone obviously thought different as early as 1947 or before, since that's when it started showing up in the NEC.

| The various remarks about putting one's tongue on the neutral are just plain | silly. Practical people don't want to touch ANY thing of metal when | working around electricity except for the special case of where they want to | ensure they haven't picked up a static charge that might "zap" some silicon. | | If you MUST tough metal you touch "ground" first, then neutral and you just | DON'T touch hot.

What is the reason for GFCI protecting a hot tub if people are not touching the wires? Well, I think the reason is because something can go wrong. Maybe water can leak into the eletronics and create a path from a wire to the people. As you step in or out of the tub, you could then complete a circuit between that wire and real ground. If there was no risk of voltage on the neutral, we wouldn't have to have separate grounding wires. IMHO, it's only the groundING wire that needs to stay connected. The neutral is groundED somewhere, but that can be far away, and there is no option to allow additional grounding nearby (as that creates the dual return path problem).

| The three wire stove and clothes dryer circuits (even with the motor running | on 120) are perfectly safe.

So why does the NEC now require the groundING wire on these in new or upgrade construction?

| Obviously, you have to do what the local law and the code require but there | is nothing dangerous about the three wire (neutral bonded to the chassis of | the appliance) connection.

So you are saying they added this requirement to the code for no technical or safety reason? Maybe it's because the members of the code committee want to see the wire companies they have invested in do better by requiring more wire in building construction?

| For every "war story" you come up with that makes the 3 wire circuit look | back I can came up with a more likely "story" making the 4 wire circuit look | bad.

I'm interested in mitigating every safety hazard. I believe the neutral is a hazard in wet areas, although not as much of one as the hot wires. I'm not going to step back from trying to mitigate a hazard I see just because some other hazards also exist. Switches, disconnects, and breakers can be made, and many do exist, that are intended (and listed) to disconnect hot and neutral wires safely (disconnect hot before neutral, such as by a variation in blade or contact angle). They just aren't made in conjunction with GFCI protection in 2-pole breakers. But they ARE made that way in receptacles from what a few people have told me (I've yet to tear one open to verify).

Test your GFCI receptacle and see if it trips when a short is placed between the neutral and the ground.