3 way switch and power.

[LarryFine]

I have heard that eventually it will be code that all switch boxes will have to have a neutral (grounded conductor) available, the reasoning is for occupancy sensor switches and other devices that control lights to save energy.

Many home-automation devices have the same requirement; for technical reasons, not political ones.

 

[quogueelectric]

Many home-automation devices have the same requirement; for technical reasons, not political ones.

Some of them seem to use the ground wire as a return for a minute power current for the internal electronics I dont feel this is a particularly good idea.

 

[ultramegabob]

Some of them seem to use the ground wire as a return for a minute power current for the internal electronics I dont feel this is a particularly good idea.

As I understand it, that is exactly the reason they will be pushing for the required neutral, the more of these devices people will be using in the future, the more current will add up on the ground....

 

[mcclary's electrical]

As I understand it, that is exactly the reason they will be pushing for the required neutral, the more of these devices people will be using in the future, the more current will add up on the ground....

That's not always the case. If they're efficient enough, it could work with resistors. A lighted doorbell lights with no neutral.

 

[iwire]

That's not always the case. If they're efficient enough, it could work with resistors. A lighted doorbell lights with no neutral.

Yes many devices do work without using the a neutral or EGC but many are in fact UL listed and use the EGC as a current carrying conductor.

 

[peter d]

I believe the devices that use the EGC as a "neutral" for the devices internal electronics have a current that is in the micro amp range on the grounding conductor. Still an NEC violation though. What a strange conflict between the UL and the NEC. :-?

 

[LarryFine]

As I understand it, that is exactly the reason they will be pushing for the required neutral, the more of these devices people will be using in the future, the more current will add up on the ground....

Which will still balance out in the service if they happen to be equal across the lines.

 

[hurk27]

I have heard that eventually it will be code that all switch boxes will have to have a neutral (grounded conductor) available, the reasoning is for occupancy sensor switches and other devices that control lights to save energy.

I would think that as these devices are brought out, at some time they would be required to be reverse compatible with older wiring systems, and as such would still have to be able to be used without a neutral at the switch location, I just think a standard that is compatible with both UL and the NEC should be implemented, such as the devices that use the power across the open switch to power the device, most have a little cap or battery that charges when the load is off, and keeps the device working while the load is on, thus not using the EGC for any current, there are many devices that use this system, but then again there are those that use the EGC for neutral return, I just don't think UL has required a standard to prevent this.

example of devices that use to load feed thru voltage is:
Lighted switches that light when switch is off
dimmers
some two wire photo cells
some event timers such as the Intermatic programmable switch box mount type.
and even some two wire motion detectors.

As for the OP, switch legs, or as some call them "dead end switches", have been used for years, and adding a unused neutral does nothing to prevent heuristic heating of the metal conduit of preventing a electric field around the circuit, as the switch leg itself does this, the neutral will not have any current on it so it would do nothing, the supply and return in the switch leg is all that is needed because it will cancel out any EMF effect, as they are 180? out of phase anyway, doesn't matter if its a 3-way or a single pole circuit. now running travelers between 3-ways or 3-ways and 4-ways can cause this if they are not run with the neutral feeding the load, or the return of the Switch leg feeding the light, but the NEC only cares about that if it is run in a ferrous metal raceway.

 

[TobyD]

On a residental(or etc) application of 3way swithed lighting outlets, I tell all my men to remember this.Power on one end-- switch leg on the other-- two travler conductors from switch to switch.And a neutral unbroken to the lighting outlet.

 

[strippers&dykes]

I just use 2 12-2's and cap one off??

If you feed the 3-way at one end with a hot and switch at the other end you can use one 12-2 using the black and white for your traverlers. This will work just fine.

 

[TobyD]

True---That will save you money.Esp. on multiple 4 way applications.I recently finised a dwelling that each and every light outside was contolled at each exterior door.I had around 100- 3ways total and 30 -or so 4ways.The owner wouldn't talk about a cental lighting board panel.It would have looked much nicer too have had all the neat little switches arranged accordingly.

 

[mivey]

If you feed the 3-way at one end with a hot and switch at the other end you can use one 12-2 using the black and white for your traverlers. This will work just fine.

Can you spell EMF?

 

[LarryFine]

I recently finised a dwelling that each and every light outside was contolled at each exterior door.I had around 100- 3ways total and 30 -or so 4ways.The owner wouldn't talk about a cental lighting board panel.It would have looked much nicer too have had all the neat little switches arranged accordingly.

Even plain ol' X-10 stuff would have been better than that, not to mention cheaper. :roll:

 

[TobyD]

Yes Sir...This was a older gentleman that was a very good customer.But,he was just plain hard headed.He was more worried about his tractor shed and his man cave than too cosmeticly dress up the elec .But, he did opt. for decora wall switches.LOL(old..wait a minute now)

 

[Bryan Ferguson]

Can you spell EMF?

I don't see how EMF would be a problem, it would be no different then just bringing down a hot and switch leg to a single pole switch.

 

[mivey]

I don't see how EMF would be a problem, it would be no different then just bringing down a hot and switch leg to a single pole switch.

It would depend on the separation between the two 12-2's. Also, this separation can be an issue if there is ferrous material involved.

I see no problem as long as the two 12-2's are kept together. When doing this, I usually lightly twist them together throughout the run to make sure they stay together. This reduces the chance of something ferrous getting between them and causing inductive heating.

 

[hurk27]

I don't see how EMF would be a problem, it would be no different then just bringing down a hot and switch leg to a single pole switch.

Nope, not the same, travelers only have current flowing in one direction on only one of the conductors at a time, so there is no cancellation of EMF, a dead end switch leg always has current flowing down the hot and back up the switch leg, thus 180? out of phase cancellation.

so if you use a 2 conductor romex to run between two 3-ways you will have EMF, and the fact you will be having the hot at one 3-way and the switch leg at the other 3-way will also cause EMF also because the neutral for the circuit will not be running with the hot or switch leg between the 3-ways.

 

[mivey]

Nope, not the same, travelers only have current flowing in one direction on only one of the conductors at a time, so there is no cancellation of EMF, a dead end switch leg always has current flowing down the hot and back up the switch leg, thus 180? out of phase cancellation.

so if you use a 2 conductor romex to run between two 3-ways you will have EMF, and the fact you will be having the hot at one 3-way and the switch leg at the other 3-way will also cause EMF also because the neutral for the circuit will not be running with the hot or switch leg between the 3-ways.

I was hoping they were talking about using two 12-2's between the 3-way switches. One 12-2 between the switches is a no-no.

Add: two 12-2's in a metal box would need to exit through the same connector.

 

[hurk27]

I was hoping they were talking about using two 12-2's between the 3-way switches. One 12-2 between the switches is a no-no.

Add: two 12-2's in a metal box would need to exit through the same connector.

I thought you were commenting on this post:

If you feed the 3-way at one end with a hot and switch at the other end you can use one 12-2 using the black and white for your traverlers. This will work just fine.

and your right it is a no-no,

 

[readydave8]

On a residental(or etc) application of 3way swithed lighting outlets, I tell all my men to remember this.Power on one end-- switch leg on the other-- two travler conductors from switch to switch.And a neutral unbroken to the lighting outlet.

the common on each 3/way switch is one lug of the two on a single pole switch