being a commercial/industrial electrician I pull only the wires needed to control lighting fixtures from 2 or 3 locations and install 3 and 4 way switches.My question is,I was at a house troubleshooting (2) 3 way and (1) 4 way switch controlling an outside fixture.(which turned out to be a bad 4way but)If I wire 3 and 4 way switches I generally bring the power to the 1st 3way with 12/2 w/ground,then install a 12/3 w ground from the first 3way to the 4 way using red and black as travelers and wirenutting the neutral in the 4way switch box,extend 12/3 w ground to the 2nd 3way from the 4 way and install a 12/2 from the 2nd 3way to the light fixture for the switchleg.in this instance power was brought to the 1st 3way then a 12/3 w ground was installed to a junction box just above the 4way,(2) 12/3 with grounds were pulled from the jbox down to the 4 way switch where they used the black and reds as travelers,and the white wires were cut away at both ends because they didnt need it.a 12/3 was installed to the 2nd 3way from the j-box used for the travelers and the switchleg back to the junction box.A 12/2 with was then installed from the jbox to the outside light fixture for the switchleg to the outside fixture and the neutral was terminated in the jbox.I figure the 4 way was cut in after the fact.whhhhhhhheeeeeeewwwwww!!!!! I got to thinking if power is not brought to the 3way switch 1st there are different scenerios where 3 wires would not be needed at the 4 way,,,,,Is it common practice to cut the white conductor even if not needed or,is 12/2 usually used to the 4 way and the whites taped black since only 4 conductors are needed to terminate to the switch plus the ground? sorry this is so long.
3 way switches
- Thread starter jap2525
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Re: 3 way switches
You have to look at things a little differently when using romex,,,, It cost me .27 a ft. here but I have to get a 250' roll,,,lowes .50 ft for 50 ft 12/3 wground.I either end up with a lot left over which may not be used for months or pay double for convienience. oh well I'll stick to my specialty.
You have to look at things a little differently when using romex,,,, It cost me .27 a ft. here but I have to get a 250' roll,,,lowes .50 ft for 50 ft 12/3 wground.I either end up with a lot left over which may not be used for months or pay double for convienience. oh well I'll stick to my specialty.
physis
Senior Member
Re: 3 way switches
Out here I don't use Lowes. They seem to be about 50% to 100% higher than Home Depot and the supply joints. Sounds like about the diffence between what you said you pay and what I pay for NM.
You could always use MC, you'll be able to use that in your other life too. or you could buy 250' NM\3 and use that where you would use the NM\2 as well.
Out here I don't use Lowes. They seem to be about 50% to 100% higher than Home Depot and the supply joints. Sounds like about the diffence between what you said you pay and what I pay for NM.
You could always use MC, you'll be able to use that in your other life too. or you could buy 250' NM\3 and use that where you would use the NM\2 as well.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: 3 way switches
Keeping the travelers as the red & black all the way through the switching is a nice touch, but, not a common or uncommon setup. I submit that it is all up to the installer's ability to take in a particular setting and figure a route that minimizes labor and material while staying within the requirements of the code.
Personally, in residential, I tend to have the feed at the light with a switch loop down to either a 3way or the 4way.
But anything is fair game.
Keeping the travelers as the red & black all the way through the switching is a nice touch, but, not a common or uncommon setup. I submit that it is all up to the installer's ability to take in a particular setting and figure a route that minimizes labor and material while staying within the requirements of the code.
Personally, in residential, I tend to have the feed at the light with a switch loop down to either a 3way or the 4way.
But anything is fair game.
Re: 3 way switches
Hi jap,
How did you get 'roped' into doing residential?
As physis said, wiring general lighting with 12awg is labor intensive unless getting paid for spec'd projects. Sounds like that JB is near max with all the 12 NM conductors going in and out. If I understood the explanation, that box is packed tighter than a frog's end going South. You're a brave soul taking on someone else's rat nest. The question concerning white wires being cut away is of particular interest.
The old two wire traveler system is now obsolete and NEC non-compliant. Even though the cable interconnections sound like a short distance, the cut away whites sets up net-current conditions lacking magnetic cancelling in the loop. I am sure you know this but the 'mechanic' who installed the circuit should be made aware of NEC 300 requirements that also apply to residential.
rbj, Seattle
Hi jap,
How did you get 'roped' into doing residential?
As physis said, wiring general lighting with 12awg is labor intensive unless getting paid for spec'd projects. Sounds like that JB is near max with all the 12 NM conductors going in and out. If I understood the explanation, that box is packed tighter than a frog's end going South. You're a brave soul taking on someone else's rat nest. The question concerning white wires being cut away is of particular interest.
The old two wire traveler system is now obsolete and NEC non-compliant. Even though the cable interconnections sound like a short distance, the cut away whites sets up net-current conditions lacking magnetic cancelling in the loop. I am sure you know this but the 'mechanic' who installed the circuit should be made aware of NEC 300 requirements that also apply to residential.
rbj, Seattle
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: 3 way switches
You could make some 12-2 with red and black.Just carry a RED sharpie.
Since when was this magnetic thing a problem with NM ?
You could make some 12-2 with red and black.Just carry a RED sharpie.
Since when was this magnetic thing a problem with NM ?
- Location
- Illinois
- Occupation
- retired electrician
Re: 3 way switches
rbj,
Don
rbj,
Can you cite a code section to support this statement?
Don
Re: 3 way switches
I have wire repriced almost daily here due to fluctuation.In response to whoever asked how I got roped into residential work,,,,,,,,,You all know as well as I, if you know about electrical work you will get asked to do something from brothers,sisters,and friends all the time.I can't even go to church without someone pulling me aside.Oh well, I just like doing electrical work no matter what kind.
I have wire repriced almost daily here due to fluctuation.In response to whoever asked how I got roped into residential work,,,,,,,,,You all know as well as I, if you know about electrical work you will get asked to do something from brothers,sisters,and friends all the time.I can't even go to church without someone pulling me aside.Oh well, I just like doing electrical work no matter what kind.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: 3 way switches
In my area, the State expects to see the boxes stripped out and made up at the roughin. Makes it a lot easier to twist the travellers together & associate the conductor that goes to the common terminal with the specific traveller when you can most readily tell.
Yup! If the previous installer doesn't leave the ends coded in some discernable manner, someone gets to pay for my time figuring out which conductor goes where.
In my area, the State expects to see the boxes stripped out and made up at the roughin. Makes it a lot easier to twist the travellers together & associate the conductor that goes to the common terminal with the specific traveller when you can most readily tell.
Re: 3 way switches
Don,
300.3 Conductors
"(B)All Conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted in accordance with 300.3(B)(1) through (4)."
Even though the 3-way two wire traveler is not specifically mentioned, wouldn't it be non-compliant if there is no return circuit in the same cable as specified in 300.3? If there is an exception to disqualify the above I will recant my observation. Concern for safety from radiated magnetic induction is also mentioned in 300.20(A).
rbj, Seattle
Don,
300.3 Conductors
"(B)All Conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord, unless otherwise permitted in accordance with 300.3(B)(1) through (4)."
Even though the 3-way two wire traveler is not specifically mentioned, wouldn't it be non-compliant if there is no return circuit in the same cable as specified in 300.3? If there is an exception to disqualify the above I will recant my observation. Concern for safety from radiated magnetic induction is also mentioned in 300.20(A).
rbj, Seattle
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: 3 way switches
RBJ,
300.3(B)(3) is the exception, just that it is not an "exception" because it is a description of wiring that is "permitted".
And:
RBJ,
300.3(B)(3) is the exception, just that it is not an "exception" because it is a description of wiring that is "permitted".
That is, conductors not in a nonferrous method have to be contained in the same raceway, cable, etc.
And:
This is about minimizing induced currents in metal, not minimizing the fields. In any case, common wiring materials in many dwellings are non-metallic. The boxes used, being non-metallic, aren't affected by 300.20(B).
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