I have one 20amp circuit that runs from the panel box to an accessible junction box in my attic via 12/2 romex. This junction box also contains the 12/2 romex switch leg runs of all six lighting fixtures that the switch box will control. Directly below this junction box in the stud bay of the wall I have a six gang switch box that will be powered by this circuit and that will receive all six switch legs. I will be running fmc from the attic junction box to the switch box with 12 gauge THHN. My question is if it is acceptable to tie all ground wires together in the attic junction box and just run 1 pigtailed ground wire to the switch box and then pigtail 6 ground wires off that 1 ground to the device switches. And repeat this for the neutral wires. Or do I need to run all six switch leg grounds and line ground through the fmc into the switch box, tie together there and then pigtail to devices? Looking to save space in the switch box obviously;-)
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1Do not take my word, but a single circuit should only need a single neutral and ground wire in the switch box(6 gang). The only time you should have 6 neutrals/ground is from the lights themselves.– crip659Commented Jun 22 at 21:04
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Are you expecting any of those 6 switches will require a neutral connection?– Robert ChapinCommented Jun 22 at 22:41
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@RobertChapin Does not matter. New code requires neutral to be in switch boxes if needed or not. The cheap way of taping white as hot, is not allowed anymore, at switches.– crip659Commented Jun 22 at 23:41
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1@crip659 My reading of this question is whether or not 6+ separate neutral wires need to be run in a single conduit. I think it's relevant to clarify the question.– Robert ChapinCommented Jun 23 at 0:04
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Yes, the six devices in the switch box are all smart dimmers that require a neutral. But to clarify, my goal is to tie all neutrals and all grounds together in the attic junction box and then bring one pigtailed neutral and one pigtailed ground into the switch box and pigtail from that to the devices in order to save box space. I could also just pigtail each device and run all wires up to attic junction box to connect, so I guess my question is really more about whether NEC requires connections be in the switch box itself or if it is acceptable to have them in the junction box above?– 10SexyApplesCommented Jun 23 at 0:05
3 Answers
I have one 20amp circuit that runs from the panel box to an accessible junction box in my attic via 12/2 romex.
With only one circuit, it will be possible to splice all of the neutral wires. It is unlikely that you can do this with a single splice using 8 wires. Instead, you will need 2 or 3 neutral splices with pigtails between them.
This also applies to the 7+ ground ground wires. Use at least 2 wire nuts for those and attach an extra pigtail to the box.
Make sure this junction box is appropriately large for the box fill calculation. You're going to have 22 of those 12 ga wires inside.
This junction box also contains the 12/2 romex switch leg runs of all six lighting fixtures that the switch box will control.
Let's NOT call these switch legs. You've got 6 cables to the lights, and each cable will need to be controlled by a separate switch. Each cable will also contain a neutral wire to complete the circuit. So that's 12/2 for switched hot and neutral, not a switch loop.
Directly below this junction box in the stud bay of the wall I have a six gang switch box that will be powered by this circuit and that will receive all six switch legs.
Yes, these are the 6 "switch loops" except you will need only one always-hot wire. So 1 always hot, 6 switched hot, 1 neutral, and an equipment grounding conductor.
I will be running fmc from the attic junction box to the switch box with 12 gauge THHN.
Make sure the FMC is appropriately large for the number of wires. Also make sure the FMC is not in an exposed location subject to damage, such as an accessible storage area. The same rule applies to Romex, so shouldn't be a concern as long as the j-box is located appropriately.
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@bmargulies It's a 20 amp circuit. 14 ga circuit conductors are not allowed in that situation. Commented Jun 23 at 23:22
Separate neutrals per circuit (in this context the "grounded circuit conductor" is another name for neutral):
200.4 Neutral Conductors. Neutral conductors shall be installed in accordance with 200.4(A) and (B).
(A) Installation. Neutral conductors shall not be used for more than one branch circuit, for more than one multiwire branch circuit, or for more than one set of ungrounded feeder conductors unless specifically permitted elsewhere in this Code. Informational Note: See 215.4 for information on common neutrals.
(B) Multiple Circuits. Where more than one neutral conductor associated with different circuits is in an enclosure, grounded circuit conductors of each circuit shall be identified or grouped to correspond with the ungrounded circuit conductor(s) by wire markers, cable ties, or similar means in at least one location within the enclosure. Exception No. 1: The requirement for grouping or identifying shall not apply if the branch-circuit or feeder conductors enter from a cable or a raceway unique to the circuit that makes the grouping obvious. Exception No. 2: The requirement for grouping or identifying shall not apply where branch-circuit conductors pass through a box or conduit body without a loop as described in 314.16(B)(1) or without a splice or termination.
Combine and connect grounds:
250.122(C) Multiple Circuits. A single equipment grounding conductor shall be permitted to be installed for multiple circuits that are installed in the same raceway, cable, trench, or cable tray. It shall be sized from Table 250.122 for the largest overcurrent device protecting circuit conductors in the raceway, cable, trench, or cable tray. Equipment grounding conductors installed in cable trays shall meet the minimum requirements of 392.10(B)(1)(c).
250.148 Continuity of Equipment Grounding Conductors and Attachment in Boxes. If circuit conductors are spliced within a box or terminated on equipment within or supported by a box, the installation shall comply with 250.148(A) through (D). Exception: The equipment grounding conductor permitted in 250.146(D) shall not be required to be connected to the other equipment grounding conductors or to the box.
(A) Connections and Splices All equipment grounding conductors that are spliced or terminated within the box shall be connected together. Connections and splices shall be made in accordance with 110.14(B) and 250.8 except that insulation shall not be required.
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Also note 310.10(G) Conductors in Parallel. (1) General. Aluminum, copper-clad aluminum, or copper circuit conductors for each ungrounded conductor, grounded conductor, or neutral conductor shall be permitted to be connected in parallel (electrically joined at both ends) only in sizes 1/0 AWG and larger and shall be installed in accordance with 310.10(G)(2) through (G)(4) Commented Jun 23 at 2:41
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1I did mention this entire switch box and the junction box directly above it in the attic are all on one dedicated circuit right? If not, I hope that clarifies. I don’t see anything in the codes listed that would prohibit the connections being done the way I mentioned. Am I missing something here in my understanding? Commented Jun 23 at 6:42
You might be better off if you use conduit between the junction box and the switch box. Instead of romex, run 8 or 9 individual wires: permanent hot, neutral, 6 switched hot and ground (unless you use metallic conduit; that can serve as ground).
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I am running FMC between attic junction and wall switch box. I believe you are confirming that what I want to do is code compliant. I added additional clarity to my question. I just wasn’t sure about making all those connections in the junction box rather than the switch box. Never had the luxury of this type of setup where there was anywhere other than the switch box itself to accept all the switch legs ( aka loops ) and power. Commented Jun 23 at 21:33