Wiring question

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wrote:

Along those lines, concerning practical wiring, the whole thing is rather funny, don't you think? We have Andy desperately trying to give Ivan an excuse to go tap in to another neutral. But for what useful purpose? You and I know that in almost all cases, if you can go find another neutral, you can find the hot that goes with it. Last time I checked, Romex comes with two conductors, so what is achieved by running only the neutral back, instead of both the hot and neutral and moving the light entirely to the other circuit? Doing the latter makes it code compliant, standard practice and is no more work.
Maybe Andy the EE can answer that for us.
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On 9/17/2011 1:33 PM, snipped-for-privacy@optonline.net wrote:

Well, it would be, if it weren't for the potential hazards.

Don't hold your breath...
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On 9/17/2011 9:33 AM, Andy wrote:

Yes, I know that. You don't seem to understand the concept of parallel circuits. If your body is grounded, and also in contact with the neutral conductor, there are two parallel paths to ground: one through the neutral conductor, and one through your body.
Most of the current will flow through the copper conductors. But it takes only a few tens of milliamps to interfere with heart rhythms.

In the sense that you're equally able to get a shock from each, I'd agree.

An EE that doesn't understand parallel circuits? Yeah, riiiiight.
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On Sat, 17 Sep 2011 12:00:24 -0400, Doug Miller

1ma is the threshold of sensory perception - less than 1ma the average person can NOT detect. 5ma can be considered to be "dangerous" 20-30ma is a strong enough shock that you "can't let go" and at anywhere between 100 and 300ma the heart is affected and death is likely. 6 amps will stop the heart - after which normal rythm can be returned (defibrilator) That is current THROUGH THE BODY. If ALL of that current flows through the HEART MUSCLE, several milliamps CAN be fatal.

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wrote:

Andy comments:
You forget that the neutral circuit is connected to ground in the panel. Nobody can get "shocked" by touching two separate white wires, assuming they are connected together in the panel, where they are also connected to the bare copper safety wiring, which is also connected to the big metal rod which goes into the ground, as well as the center conductor of the transformer on the pole (or wherever), which also goes to a ground rod......etc....
Draw yourself a schematic , and you will understand.....
Andy in Eureka, Texas
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Obviously the whole discussion is way beyond your comprehension at this point. An analysis has been given based on parallel circuits with some real resistances that show you can in fact get shocked. And that is because those neturals are not perfect conductors, they do have resistance, and hence there can be voltage potential between them at various points along their runs and ground.
Will it kill you, shock you severly, or burn down your house? Probably not, IF everything you assume and everything in the other circuit you tap into is working correctly. And IF someone in the future doesn't come along and add on to the wall switch wiring, putting in more outlets for example, then you have do have something with lethal potential. How lucky do you feel gambling with other people's safety?
The other interesting thing is that you and CL presume to know exactly the amount of current that unknown, generic X10 switch will send down this illegal tapped neutral. We don't even know which specific one it is or what the actual current it will send down the neutral is. CL is making the assumption that it is almost non-existent. Since we don't even know the specific switch obviously neither of you can know that.
Suppose it's instead 30ma which is enough to kill someone working on the other circuit which they believe to be de-energized? These X10 things are cheap crap made in China, so how do you know it won't have some failure that results in say 75ma going down the neutral which is enough to kill someone? How about someone replaces that X10 with something else someday, say a combined switch and outlet that sends 5 amps down the neutral?
Those are the real safety issues the folks who write the NEC are aware of and why the rule exists.
BTW, Doug and I are still waiting for an answer from you guys who think tapping another neutral is an OK idea. If you can run a new neutral back to that X10 switch, from another circuit, then why can't you just run a hot back there too, connecting the X10 switch to the hot and neutral from the same circuit? Last time I checked, Romex has two current carrying conductors, so the wire is free. You could almost always do it safely and legally with the same amount of work, same cost, so why are you advocating doing this half-assed nonsense?
Even more bizarre, if his loads are just incandescent lights, the whole problem can be solved by just using an X10 swtich that works without a neutral at all. They are readily available.
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On 9/17/2011 8:58 PM, Andy wrote:

That is, quite simply, utterly false. If you are grounded, and touch the neutral wire of an energized circuit, you *can* get a shock because you've created a parallel circuit, one leg of which is your body.

Take your own advice.
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On Fri, 16 Sep 2011 07:15:33 -0400, Doug Miller

dangerous. The neutral is only required to activate the x10 switch. It is NOT a load neutral 3 connections on the X10 device' Line in , Line out, and neutral. The neutral is only used by the control circuit - which is a voltage controlled switch - not current controlled (think j-fet vs bipolar transistor) -
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On 9/16/2011 8:42 PM, snipped-for-privacy@snyder.on.ca wrote:

Yes, it is necessarily dangerous. We're discussing specifically pulling a neutral from *another circuit*. The current in the neutral will be whatever currrent is drawn by the load operating on the *other* circuit, not the current in the X10 device.
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On Sat, 17 Sep 2011 09:26:33 -0400, Doug Miller

so the neutral is still SAFE. ALL neutrals are the same potential zero volts to ground - unless the neutral is "lifted".
If you shut off the circuit the X10 is used on, the "other circuit" neutral is still zero volts. So it is not an issue.
If you shut off the "other circuit" to work on IT, the neutral from the x10 is not carrying any load - so although a sensitive voltmeter MAY show a voltage, there will not be enough current to shock you. It MAY give you a barely perceptible tingle. and then only, as I said before, if the neutral is "lifted" - ie - the wire from the x10 is separated from the circuit neutral, the circuit neutral is opened somewhere between that connection and the neutral buss (ground) or the neutral is disconnected from the buss.
So the chances that it would EVER be dangerous are extremely remote. It is, however, still against code.
The reason it is against code is because, having the "off circuit" neutral in the box with the live line, someone down the road COULD connect a load to that neutral. As soon as a load is connected to that neutral ALL of the situations everyone is worried about BECOME possibilities. The neutral just for the X10 device is NOT, in itself, a safety issue.
Again - I would NOT recommend it. It IS contrary to code (so you could say it is illegal) - but it is not, necessarily, dangerous.
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On 9/17/2011 7:45 PM, snipped-for-privacy@snyder.on.ca wrote:

In an ideal world, perhaps. In the real world, where houses are not wired with superconducting cable, copper wire has a very low but definitely non-zero resistance. And splices in copper wire have a very low but definitely non-zero resistance. And the potential difference between the electrical system grounding electrode and the water pipe, for example, that you're touching is not necessarily zero.

NO IT'S NOT. The neutral carries current.

That doesn't matter. If your body is also at ground potential, and you contact the neutral, your body forms a parallel path for that current to return to ground.
Granted, most of that current will be in the neutral conductor, and not in your body -- but it doesn't take very much to kill you. Why do you suppose the trip threshold on a GFCI is only 20mA?

Wrong again. If there is a load on the other circuit, there is current flowing in the neutral wire. If you touch it while you are grounded, you have formed a parallel path to ground for some of that current to return through your body.
Worse, if you *open* a splice in that neutral, not knowing that it's carrying current from some other circuit, you may have formed a parallel path to ground for *all* of that current to return through your body.

Nobody ever claimed that the tiny current drawn by the X10 device constituted a hazard of any sort.

Right. It's against Code because ... wait for it ... it's DANGEROUS.

And that "someone down the road" could be as simple as someone turning on an appliance in the kitchen while Ivan is installing his X10 gizmos. I would not enjoy being part of the return path for the current drawn by a toaster or microwave oven. YMMV.

Which is exactly what I've been saying all long -- that if there is a load on the other circuit, the current in the neutral is a potential hazard. Thank you for [finally] acknowledging that.

Yes, it is. I hope that you don't ever learn the hard way that you're mistaken.
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wrote:

Doug, without proof, I'm not buying into that it's a tiny current. We don't even know the specific X10 switch he's contemplating using. We do know that it's one that works any load, not just incandescents. All the ones of that type I have seen have relays. You can hear them click. A relay needs some reasonable current to pull in and I would think that current is flowing in the neutral, meaning it could be 30ma, the lethal threshold.
I think it's totally irresponsible to be advocating using a neutral from another circuit with a device that no one here even has a spec sheet on. CL and Andy are assuming the X10 switch has a "tiny" current, but no one knows that.

Another easy to understand major safety hazard is someone later replacing that X10 switch with a switch/outlet combo. Now, you have the ability to:
A - exceed the current carrying capacity of the neutral resulting in a fire
B - having the other circuit neutral with 120V when someone working on it believes it's de-energized because they opened the breaker.

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wrote:

Andy comments:
You are correct. X10 modules use internal relays....typically they are "appliance modules" which have a specific current rating, and are "reccommended" for passive, not inductive, loads (for obvious reasons).....
I use them all over the place in my house , and have written programs and built interfaces to run them from laptops, and , when I needed to have one do "more" than their ratings, used a big ass contactor (technical term for... well... big ass contactor ) to handle the problem....
Andy in Eureka, P.E.
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What does the above have to do with anything? Can you state what current the X10 switch Ivan is actualy planning on using sends down the neutral? CL and you assume it's near zero and so it just can be dismissed as harmless. I say without a spec sheet and knowing an energized relay is involved, you're full of BS.
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On Sun, 18 Sep 2011 07:57:59 -0700 (PDT), Andy

modules" and put this turkey to bed???
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On Sep 18, 2:26 pm, snipped-for-privacy@snyder.on.ca wrote:

Andy cmments: It was easier to just google it. Here is a statement made on X10 modules used with LEDs :
******************************Cut and paste ********** In the OFF state, most X10 appliance modules draw between .1 and .5 watts, depending upon the make and model. ************* end of cut and paste. *******************
So 0.1 / 110 is .000833 or about 8/10s of a milliampere.....
I'll have to go and measure the relay current in the "ON" state....
Andy in Eureka, P.E.
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Andy adds: On second thought, nothing is going to "put this turkey to bed", regardless of the information presented. There are different mindsets on this, and it's up to Ivan to figure out what he wants to do . Beyond that, it's really nobody's concern.... Good luck to Ivan.... !!!
Andy in Eureka, Texas
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It's not up to Ivan to figure out. That's why we have the NEC which specifies how wiring is done safely.
> Beyond that, it's really nobody's

I'd say it's everyone's concern. I would not want to buy a house with half-assed wiring in direct violation of NEC. When someone gets killed because of stupidity like this, it's a safety issue for the general public, because it may not be Ivan that winds up dead.
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On Mon, 19 Sep 2011 07:19:03 -0700 (PDT), " snipped-for-privacy@optonline.net"

The NEC is not universally accepted by nearly every jurisdiction in the U.S. It is modified based upon common sense and what has been effective for 30-40 years. Try to get info as to number of fires prevented by AFCI's and you meet a stone wall. How many code mods by manufacturers vs. inspectors/contractors? About 99 to 1. I was on code review committe in a major metro area for 5 years and some of the proposals were laughable.

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No one ever said the entire NEC is universally accepted by every jurisdiction. The issue at hand however is stealing a neutral from another circuit. That is a very basic part of the NEC and has been prohibited for good reason for a very long time. Was stealing a neutral allowed in the jurisdiction where you were on the committee? Can you show us one jurisdiction where that rule has not been adopted? I'll bet you can't and even if you can, the rule would still cover virtually everywhere else in the USA and I also bet it covers Ivan.
If we start accepting the idea that even the most basic parts of NEC are going to be jurisdiction dependent, then no one can answer most basic electrical wiring questions here at all. It amazes me how people will debate such a basic code provision, muddying the waters and try to give some credence to an unsafe practice which a novice might then use as a green light to go ahead and do.
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