Same circuit neutral loops.

[jklr]

Working in a house troubleshooting and came across a wiring scenario that was not the issue, but that made me think. There was a single pole switch for the living room fan and 3 way switches and a couple 4 way switches for the living room can lights and ceiling fan light. Power was brought in from a jbox in the attic to the first switch box with a hot and nuetral feeding the fan single pole and the 3 way switch for the lights. 14/2 left the switch box and went back to the jbox for the fan and 14/3 left the switch box to pick up the 4 ways and eventually land into the 3 way. From the last 3 way switch,14/2 ran and daisychained the can lights and then finally back to the original jbox. Then 14/3 was ran from the j box to the fan box for the light ( and lights and ceiling fan light on the same switch) and fan. All of the nuetrals were tied together and the switched power was tied correctly feeding all the lights and then the fan. My question is whether this is OK or not since there was a loop created on the nuetral for the lights when it left the first switch box and eventually ended up back in the original jbox. Its all on the same circuit, but never really thought about the nuetral loops on the same circuit before. I tried posting a picture of a diagram, but the server can't process as it is too large. Really just curious to know if that is a code violation?

TIA.

 

[jklr]

 

[wwhitney]

My question is whether this is OK or not since there was a loop created on the nuetral for the lights when it left the first switch box and eventually ended up back in the original jbox. Its all on the same circuit, but never really thought about the nuetral loops on the same circuit before.

If I understand your diagram correctly, you have two loops, one of which is a code violation.

The code violation loop is formed by the two 14/2s from the JB to the SP/3-way box. One is power to the box, the other is return switched power for the fan. You show both neutrals in the two cables connected in the JB, and I infer that they are also connected together in the SP/3-way box. That makes them parallel conductors, ones that are directly connected at both ends. That's not allowed for #14 AWG, just for #1/0 and larger.

The other loop is the big loop from the JB around the switches and through the cans back to the JB. If all the wiring is NM, and all the boxes nonmetallic, that's not actually a violation. But it will cause the neutral current to divide between the two ways around the loop rather than always going in the cable with the associated ungrounded conductor. So you will get some magnetic fields that you wouldn't otherwise have whenever any of the loads are on.

Now that I think about it, without pulling any new cables, you could rewire the junction box and switch boxes and get an arrangement where the neutral current is always in a cable with the associated ungrounded conductor. Let me know if you'd like me to type or draw that out. You'd end up abandoning the 14/2 between the 3-way-only box and the far can.

Cheers, Wayne

 

[jklr]

If I understand your diagram correctly, you have two loops, one of which is a code violation.

The code violation loop is formed by the two 14/2s from the JB to the SP/3-way box. One is power to the box, the other is return switched power for the fan. You show both neutrals in the two cables connected in the JB, and I infer that they are also connected together in the SP/3-way box. That makes them parallel conductors, ones that are directly connected at both ends. That's not allowed for #14 AWG, just for #1/0 and larger.

The other loop is the big loop from the JB around the switches and through the cans back to the JB. If all the wiring is NM, and all the boxes nonmetallic, that's not actually a violation. But it will cause the neutral current to divide between the two ways around the loop rather than always going in the cable with the associated ungrounded conductor. So you will get some magnetic fields that you wouldn't otherwise have whenever any of the loads are on.

Now that I think about it, without pulling any new cables, you could rewire the junction box and switch boxes and get an arrangement where the neutral current is always in a cable with the associated ungrounded conductor. Let me know if you'd like me to type or draw that out. You'd end up abandoning the 14/2 between the 3-way-only box and the far can.

Cheers, Wayne

Thank you Wayne. I would love to see a diagram.

As far as the code violations. Im assuming it violates 300.3(B)?

I want to understand, how is the 14/2 return for the fan a violation and the bigger loop for the lights not? All nuetrals are tied together and both create a loop.

When I saw the wiring set up, I didnt like it, and thought it could be wired better without the loops and then I started thinking code compliance and came here for some clarification.

 

[jklr]

Neutral pardon my spelling.

 

[wwhitney]

Thank you Wayne. I would love to see a diagram.

I'll give you a text description shortly, if that doesn't work I'll draw up a diagram.

As far as the code violations. Im assuming it violates 300.3(B)?

If all the boxes are non-metallic and the cable is NM, then 300.3(B)(3) permits the neutral to be in a different cable from the ungrounded, so the big loop is not a violation. But 310.10(H) (2017 NEC numbering) doesn't permit two segments of 14/2 to have their neutrals connected to each other at both end.

Cheers, Wayne

 

[wwhitney]

OK to get rid of the loops and keep all the neutral current in the same cable as the associated ungrounded current:

- Abandon the 14/2 between the far 3-way switch box and the can.

- In the 14/3 between the 4 boxes with switches, presumably the white is neutral and the black/red are the travelers. Relabel the white say blue and repurpose it to be the return switched hot. So in the far box with a 3-way, the white/blue gets moved to the common terminal of the 3-way.

- Between the j-box and the box with two switches you have two 14/2s, so 2 whites and 2 black. Relabel to make it a white, a black, a blue, and a purple.

- In the box with two switches, the white is a neutral that just gets capped for future use as required. The black is incoming hot, and it supplies power to one side of the single pole switch and the common point of the 3-way switch. The blue is light switched power and gets connected to the blue in the 14/3. The purple is fan switch power and goes to the other side of the single pole switch.

-And now in the j-box you have white neutral, blue light switched power (which connects to one of the non-white in the 14/3 to the fan/light as well as to the 14/2 going to a can) and purple fan switched power (which connects to the other non-white in the 14/3 to the fan/light).

Cheers, Wayne

 

[jap]

Generally, when yo

OK to get rid of the loops and keep all the neutral current in the same cable as the associated ungrounded current:

- Abandon the 14/2 between the far 3-way switch box and the can.

- In the 14/3 between the 4 boxes with switches, presumably the white is neutral and the black/red are the travelers. Relabel the white say blue and repurpose it to be the return switched hot. So in the far box with a 3-way, the white/blue gets moved to the common terminal of the 3-way.

- Between the j-box and the box with two switches you have two 14/2s, so 2 whites and 2 black. Relabel to make it a white, a black, a blue, and a purple.

- In the box with two switches, the white is a neutral that just gets capped for future use as required. The black is incoming hot, and it supplies power to one side of the single pole switch and the common point of the 3-way switch. The blue is light switched power and gets connected to the blue in the 14/3. The purple is fan switch power and goes to the other side of the single pole switch.

-And now in the j-box you have white neutral, blue light switched power (which connects to one of the non-white in the 14/3 to the fan/light as well as to the 14/2 going to a can) and purple fan switched power (which connects to the other non-white in the 14/3 to the fan/light).

Cheers, Wayne

I thought about this also, but, with the new code rules, unless all the switch boxes are accessible, doesn't there need to be a Neutral conductor in each of the switch boxes ?

In that case the white could not be re-purposed for a return conductor could it?

Jap>

 

[wwhitney]

I thought about this also, but, with the new code rules, unless all the switch boxes are accessible, doesn't there need to be a Neutral conductor in each of the switch boxes ?

404.2(C) only requires it in one box if that box can see the full area being lit. So hopefully that's true for the box with two switches. But even if not, the exception says that it doesn't apply to existing installations.

Cheers, Wayne

 

[jap]

OK to get rid of the loops and keep all the neutral current in the same cable as the associated ungrounded current:

- Abandon the 14/2 between the far 3-way switch box and the can.

- In the 14/3 between the 4 boxes with switches, presumably the white is neutral and the black/red are the travelers. Relabel the white say blue and repurpose it to be the return switched hot. So in the far box with a 3-way, the white/blue gets moved to the common terminal of the 3-way.

- Between the j-box and the box with two switches you have two 14/2s, so 2 whites and 2 black. Relabel to make it a white, a black, a blue, and a purple.

- In the box with two switches, the white is a neutral that just gets capped for future use as required. The black is incoming hot, and it supplies power to one side of the single pole switch and the common point of the 3-way switch. The blue is light switched power and gets connected to the blue in the 14/3. The purple is fan switch power and goes to the other side of the single pole switch.

-And now in the j-box you have white neutral, blue light switched power (which connects to one of the non-white in the 14/3 to the fan/light as well as to the 14/2 going to a can) and purple fan switched power (which connects to the other non-white in the 14/3 to the fan/light).

Cheers, Wayne

Which is the way we've most always done it other than the fact that power was generally brought directly to the first switch box which negated the need of the J-Box.

Now days,it's getting more and more common to see smart switches installed at the first switch box and remote (Picos only) at the remaining switch locations.

Jap>