# 3-Way Switch. Take Neutral from another Outlet?



## raider1 (Jan 22, 2007)

Check out 300.3(B)(3)

Chris


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## Dennis Alwon (May 9, 2009)

You will create unwanted emf's doing this install. If I understand you correctly and the wiring is non metallic it is compliant-- same circuit etc.


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## Tator (Aug 19, 2011)

*Quote*

The Light will Work but it is not legal to do it that way


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## don_resqcapt19 (Jul 18, 2010)

Tator said:


> The Light will Work but it is not legal to do it that way


Please cite the code section that says you can't do it that way.


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## Dennis Alwon (May 9, 2009)

don_resqcapt19 said:


> Please cite the code section that says you can't do it that way.


Now you know he won't be able to do that. :laughing:


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## Tator (Aug 19, 2011)

300.5(I) page 130 in 2008 NEC ( same raceway or cable)


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## Dennis Alwon (May 9, 2009)

Tator said:


> 300.5(I) page 130 in 2008 NEC ( same raceway or cable)


For one that is underground installations. Did you read what Chris stated in the second post? Art. 300.3(B)(3)


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## swimmer (Mar 19, 2011)

Thanks for answering my question. 

Another 300.3(B) issue I've discussed, in the forum, is the switch leg in EMT or 12/2 Armored Metallic Cable. This is where one wire delivers power to the switch and the second wire runs from the switch back to the outlet being controlled. There is no neutral.

300.3(B) says "All conductors of the same circuit and, *where used*, the grounded conductors..."

So it sounds like, even for metal conduit and armored cable, you are allowed to run the switch leg without the neutral. I guess that since the current runs in opposite directions in the 2 wires, the magnetic field cancels and the metal conduit or armor does not heat.

I don't do much commercial but I'm pretty sure I recall working on these types of neutral-less switch legs in metal conduit but I know better than to trust my memory.

Anyone ever heat up a piece of EMT by running the black wire through the EMT and running the white wire outside the EMT? I tried it with a 4A load and got absolutely no heat. Also, my clamp-on meter read the exact same 4A on both the bare wire and the EMT enclosed wire. This tells me the magnetic field is the same whether or not the wire is enclosed by EMT and that the EMT is absorbing no energy. No energy ===> No heat.


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## don_resqcapt19 (Jul 18, 2010)

swimmer said:


> ...
> Anyone ever heat up a piece of EMT by running the black wire through the EMT and running the white wire outside the EMT? I tried it with a 4A load and got absolutely no heat. Also, my clamp-on meter read the exact same 4A on both the bare wire and the EMT enclosed wire. This tells me the magnetic field is the same whether or not the wire is enclosed by EMT and that the EMT is absorbing no energy. No energy ===> No heat.


You won't get heat with small currents. The NEC is a very conservative code. The equivalent rule in the Canadian Electrical Code does not apply unless the circuit currents exceed 200 amps. They understand that there is no issue with inductive heating at currents below 200.


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## Mr. Troubleshooter (Aug 21, 2011)

swimmer said:


> I'd like to convert a standard light circuit to a 3-way. i.e. 1 light controlled by 2 switches.
> I'd like to use the existing 12/2 romex run between the switch box (box 1) and the light outlet box (box 2) as travelers. This is because running 12/3 from the box 1 to the box 2 will require much more work and possible drywall damage even if I try using the existing 12/2 as a pull rope.
> 
> To get neutral to the light outlet:
> ...


Dude, just run the 12/3


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## Murphy (Dec 10, 2009)

Mr. Troubleshooter said:


> Dude, just run the 12/3


seriously.. if you care enough to ask us..then you should care enough to do the job right..


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## jza (Oct 31, 2009)

swimmer said:


> I'd like to convert a standard light circuit to a 3-way. i.e. 1 light controlled by 2 switches.


Ohhh, that's what a 3 way is!!


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## BuzzKill (Oct 27, 2008)

Dennis Alwon said:


> For one that is underground installations. Did you read what Chris stated in the second post? Art. 300.3(B)(3)


Don't question Chris!


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