Let’s say you run a two wire cable for travellers between two switch boxes. Then you run another 2 wire between those two boxes for hot and neutral which carries on to other devices. Will the code gods smite you for not using a 4 wire?
I disagree. Those rules and exceptions are not meant to be used when running multi-wire cables, they are for single conductor. The CEC also has similar codes for when doing that.@HertzHound, that’️s not the way I read it. 300.20(b) is referring to single conductors, not conductors of a multiwire cable.
The NEC is confusing. 300.3(b)(3) Say's it's allowed as long as 300.20(b) is followed. Yes 300.20(b) is for single conductors but it's 300.3(b)(3) that got you there.
(3)Nonferrous Wiring Methods.
Conductors in wiring methods with a nonmetallic or other nonmagnetic sheath, where run in different raceways, auxiliary gutters, cable trays, trenches, cables, or cords, shall comply with the provisions of 300.20(B).
No one told me there are ET mugs!!!Maybe we can get Cricket to throw in an ET mug to to the correct interpretation?![]()
I dont know about your area ever sell 14/4 verison loomex .,,So who sells 14/4 loomex?
Of course it was done in the past before 3 wire was around. Knob and tube is still seen in older houses today but that does not mean we can wire receptacles and switches with single conductors today.Yes it done pretty often in old days before the XX/3 NM or loomex is common but you really have to watch how it connected cuz there is not much clue to give out so pay attention to the travelers.
I think Dennis will agree with me with old set up. but currentaly it kinda super rare unless special situation arise.
Mugs & Tee shirts.No one told me there are ET mugs!!!
Heck I'd like to just get the logo to print on stuff.I’d buy a mug if it was available.
You can not run separate wires. All the wires for a circuit must be contained in the same multi conductor cable. 12-106(1)Run a 2-wire to the first box and then to the second. That will give you a neutral in each box to satisfy the neutral requirement. Then a 3-wire between the same two boxes will give you two travellers and a switch return or a hot and 2 travellers depending on where you start your switching from.
From where you end your switching, a 2-wire to your load. Or 3 if you want to take the hot.
Or use 4 wire BX.
Yes, the nec does allow this install as long as it is nm cable. I have tried to get it changed but the nec panel does not care about electromagnetic field's.I disagree. Those rules and exceptions are not meant to be used when running multi-wire cables, they are for single conductor. The CEC also has similar codes for when doing that.
@Dennis Alwon, what is your interpretation of these NEC articles? Can a circuit be split up into different multi wire cables for three way switching and are the NEC articles posted allowing it?
I still disagree. The exemptions and codes from the NEC posted are clearly for single conductor cables.Yes, the nec does allow this install as long as it is nm cable. I have tried to get it changed but the nec panel does not care about electromagnetic field's.
Of course the easiest install is using 3 wire cable between the switches and then feed one 3 way and switch leg from the other
We use plastic boxes.I still disagree. The exemptions and codes from the NEC posted are clearly for single conductor cables.
If not, does that mean you have to cut the metal between the holes where the wire enters in the switch box as per 300.20(b) ? Seriously? This is an actual practice done in residential? Seems silly as that is really only required for currents over 200 amps which is why the rule is meant for single conductors, not nm cable.
The only reason the code allows it is so that existing installs are left alone. Some inspectors love to see a new code and demand that old stuff be ripped out, so I think this was put in to prevent that.I still disagree. The exemptions and codes from the NEC posted are clearly for single conductor cables.
If not, does that mean you have to cut the metal between the holes where the wire enters in the switch box as per 300.20(b) ? Seriously? This is an actual practice done in residential? Seems silly as that is really only required for currents over 200 amps which is why the rule is meant for single conductors, not nm cable.
We can’t even use plastic straws!!!We use plastic boxes.
Yes, you would if you used metal boxes. Very rarely do we encounter this...I still disagree. The exemptions and codes from the NEC posted are clearly for single conductor cables.
If not, does that mean you have to cut the metal between the holes where the wire enters in the switch box as per 300.20(b) ? Seriously? This is an actual practice done in residential? Seems silly as that is really only required for currents over 200 amps which is why the rule is meant for single conductors, not nm cable.
I agree it does seem wrong and I will never do it however it is compliant.We can’t even use plastic straws!!!
:vs_laugh:
Our code does not allow it regardless of type of box. It just seems wrong to me as this is basic stuff taught to us from first year.