Is this wiring safe and is it according to code?

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A single 12-3 cable was run to a double switch to control individual lights. The white is used as a hot, is this wiring correct/per NEC code?



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  • 1




    Why are you asking about this? Are you trying to put a smart-switch here?
    – ThreePhaseEel
    Nov 26 at 4:49






  • 1




    While you've got it open anyways you might put black tape on the white hot wire, to lessen any possible confusion of future homeowners who encounter this switch.
    – Eric Lippert
    Nov 26 at 15:04






  • 1




    As an additional minor issue, it looks like the bonding wire is not actually secured to the box - it goes straight to the switches. I don't know that it was ever code to do it that way, but the ground wire should be screwed to the box first, then carry on to the devices in the box.
    – J...
    Nov 26 at 16:06






  • 1




    @J... Except the metal surface of the fbox is flush with the wall, and the metal yoke of the switch appears able to bottom hard on it. That is an acceptable grounding path if that surface is clean bare metal with nothing in between. Would be better to ground the box rather than the yoke, though.
    – Harper
    Nov 27 at 0:37






  • 1




    @ThreephaseEel - I just try to put a dimmer on it. This house had a lot of bx wires. I am curious even if you ground on the box, it won't actually grounded or trip the fuse.
    – Jemilianl
    Nov 27 at 5:21
















up vote
10
down vote

favorite












A single 12-3 cable was run to a double switch to control individual lights. The white is used as a hot, is this wiring correct/per NEC code?



enter image description here










share|improve this question



















  • 1




    Why are you asking about this? Are you trying to put a smart-switch here?
    – ThreePhaseEel
    Nov 26 at 4:49






  • 1




    While you've got it open anyways you might put black tape on the white hot wire, to lessen any possible confusion of future homeowners who encounter this switch.
    – Eric Lippert
    Nov 26 at 15:04






  • 1




    As an additional minor issue, it looks like the bonding wire is not actually secured to the box - it goes straight to the switches. I don't know that it was ever code to do it that way, but the ground wire should be screwed to the box first, then carry on to the devices in the box.
    – J...
    Nov 26 at 16:06






  • 1




    @J... Except the metal surface of the fbox is flush with the wall, and the metal yoke of the switch appears able to bottom hard on it. That is an acceptable grounding path if that surface is clean bare metal with nothing in between. Would be better to ground the box rather than the yoke, though.
    – Harper
    Nov 27 at 0:37






  • 1




    @ThreephaseEel - I just try to put a dimmer on it. This house had a lot of bx wires. I am curious even if you ground on the box, it won't actually grounded or trip the fuse.
    – Jemilianl
    Nov 27 at 5:21












up vote
10
down vote

favorite









up vote
10
down vote

favorite











A single 12-3 cable was run to a double switch to control individual lights. The white is used as a hot, is this wiring correct/per NEC code?



enter image description here










share|improve this question















A single 12-3 cable was run to a double switch to control individual lights. The white is used as a hot, is this wiring correct/per NEC code?



enter image description here







electrical wiring code-compliance nec






share|improve this question















share|improve this question













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edited Nov 26 at 12:36









ThreePhaseEel

29.3k104490




29.3k104490










asked Nov 26 at 4:04









Jemilianl

6113




6113







  • 1




    Why are you asking about this? Are you trying to put a smart-switch here?
    – ThreePhaseEel
    Nov 26 at 4:49






  • 1




    While you've got it open anyways you might put black tape on the white hot wire, to lessen any possible confusion of future homeowners who encounter this switch.
    – Eric Lippert
    Nov 26 at 15:04






  • 1




    As an additional minor issue, it looks like the bonding wire is not actually secured to the box - it goes straight to the switches. I don't know that it was ever code to do it that way, but the ground wire should be screwed to the box first, then carry on to the devices in the box.
    – J...
    Nov 26 at 16:06






  • 1




    @J... Except the metal surface of the fbox is flush with the wall, and the metal yoke of the switch appears able to bottom hard on it. That is an acceptable grounding path if that surface is clean bare metal with nothing in between. Would be better to ground the box rather than the yoke, though.
    – Harper
    Nov 27 at 0:37






  • 1




    @ThreephaseEel - I just try to put a dimmer on it. This house had a lot of bx wires. I am curious even if you ground on the box, it won't actually grounded or trip the fuse.
    – Jemilianl
    Nov 27 at 5:21












  • 1




    Why are you asking about this? Are you trying to put a smart-switch here?
    – ThreePhaseEel
    Nov 26 at 4:49






  • 1




    While you've got it open anyways you might put black tape on the white hot wire, to lessen any possible confusion of future homeowners who encounter this switch.
    – Eric Lippert
    Nov 26 at 15:04






  • 1




    As an additional minor issue, it looks like the bonding wire is not actually secured to the box - it goes straight to the switches. I don't know that it was ever code to do it that way, but the ground wire should be screwed to the box first, then carry on to the devices in the box.
    – J...
    Nov 26 at 16:06






  • 1




    @J... Except the metal surface of the fbox is flush with the wall, and the metal yoke of the switch appears able to bottom hard on it. That is an acceptable grounding path if that surface is clean bare metal with nothing in between. Would be better to ground the box rather than the yoke, though.
    – Harper
    Nov 27 at 0:37






  • 1




    @ThreephaseEel - I just try to put a dimmer on it. This house had a lot of bx wires. I am curious even if you ground on the box, it won't actually grounded or trip the fuse.
    – Jemilianl
    Nov 27 at 5:21







1




1




Why are you asking about this? Are you trying to put a smart-switch here?
– ThreePhaseEel
Nov 26 at 4:49




Why are you asking about this? Are you trying to put a smart-switch here?
– ThreePhaseEel
Nov 26 at 4:49




1




1




While you've got it open anyways you might put black tape on the white hot wire, to lessen any possible confusion of future homeowners who encounter this switch.
– Eric Lippert
Nov 26 at 15:04




While you've got it open anyways you might put black tape on the white hot wire, to lessen any possible confusion of future homeowners who encounter this switch.
– Eric Lippert
Nov 26 at 15:04




1




1




As an additional minor issue, it looks like the bonding wire is not actually secured to the box - it goes straight to the switches. I don't know that it was ever code to do it that way, but the ground wire should be screwed to the box first, then carry on to the devices in the box.
– J...
Nov 26 at 16:06




As an additional minor issue, it looks like the bonding wire is not actually secured to the box - it goes straight to the switches. I don't know that it was ever code to do it that way, but the ground wire should be screwed to the box first, then carry on to the devices in the box.
– J...
Nov 26 at 16:06




1




1




@J... Except the metal surface of the fbox is flush with the wall, and the metal yoke of the switch appears able to bottom hard on it. That is an acceptable grounding path if that surface is clean bare metal with nothing in between. Would be better to ground the box rather than the yoke, though.
– Harper
Nov 27 at 0:37




@J... Except the metal surface of the fbox is flush with the wall, and the metal yoke of the switch appears able to bottom hard on it. That is an acceptable grounding path if that surface is clean bare metal with nothing in between. Would be better to ground the box rather than the yoke, though.
– Harper
Nov 27 at 0:37




1




1




@ThreephaseEel - I just try to put a dimmer on it. This house had a lot of bx wires. I am curious even if you ground on the box, it won't actually grounded or trip the fuse.
– Jemilianl
Nov 27 at 5:21




@ThreephaseEel - I just try to put a dimmer on it. This house had a lot of bx wires. I am curious even if you ground on the box, it won't actually grounded or trip the fuse.
– Jemilianl
Nov 27 at 5:21










1 Answer
1






active

oldest

votes

















up vote
17
down vote













There is one safety issue here



It appears that the original installer took the ground wire from the 12/3 cable, looped it around one switch ground screw, then attached it to the other switch ground screw. This grounds the switch yokes fine, but leaves the (metal) box ungrounded save through screw threads. The solution to this is to cut off the existing ground wire with some slack left, then nut it to pigtails to the switch ground screws and a ground screw (10-32) into the provided hole in the back of the box.



While you're at it, you should wrap the white wire with black tape to make it crystal clear to the next bloke looking inside the box that it's hot and not neutral.



As to Code...this used to be OK, but not any longer



Back before the 2011 NEC, an "old style" switch loop like this was permitted by the Code -- a single pole switch only needs always-hot and switched-hot, so a 12/2 cable could be used for a single switch or a 12/3 for a pair of switches sharing a hot feed, as you see here.



However, due to the increasing prevalence of remote-controlled switches, motion sensors, timers, and advanced dimmers, all of which benefit from having a neutral at the switch box to provide power to the electronics inside, the 2011 NEC added 404.2(C) to ensure that the neutral was available for such devices, in lieu of them powering themselves via a hack such as using the ground wire as the return path or trickling their operating current through the load (quoted from the 2017 NEC, save for vernacular terms in [square brackets]):




(C) Switches Controlling Lighting Loads. The grounded
circuit conductor [neutral] for the controlled lighting circuit shall be
installed at the location where switches control lighting loads
that are supplied by a grounded general-purpose branch circuit
serving bathrooms, hallways, stairways, or rooms suitable for
human habitation or occupancy as defined in the applicable
building code. Where multiple switch locations control the
same lighting load such that the entire floor area of the room
or space is visible from the single or combined switch locations,
the grounded circuit conductor [neutral] shall only be required at one
location. A grounded conductor [neutral] shall not be required to be
installed at lighting switch locations under any of the following
conditions:



(1) Where conductors enter the box enclosing the switch
through a raceway, provided that the raceway is large
enough for all contained conductors, including a grounded conductor [neutral]



(2) Where the box enclosing the switch is accessible for the
installation of an additional or replacement cable without
removing finish materials



(3) Where snap switches with integral enclosures comply with
300.15(E)



(4) Where lighting in the area is controlled by automatic
means



(5) Where a switch controls a receptacle load



The grounded conductor [neutral] shall be extended to any switch
location as necessary and shall be connected to switching devices that require line-to-neutral voltage to operate the electronics of the switch in the standby mode and shall meet the
requirements of 404.22.



Exception: The connection requirement shall become effective on January 1, 2020. It shall not apply to replacement or retrofit switches installed in locations prior to local adoption of 404.2(C) and where the
grounded conductor [neutral] cannot be extended without removing finish materials. The number of electronic lighting control switches on a branch
circuit shall not exceed five, and the number connected to any feeder on
the load side of a system or main bonding jumper shall not exceed 25.
For the purpose of this exception, a neutral busbar, in compliance with
200.2(B) and to which a main or system bonding jumper is connected
shall not be limited as to the number of electronic lighting control
switches connected.



Informational Note: The provision for a (future) grounded
conductor [neutral] is to complete a circuit path for electronic lighting
control devices.




and the 2017 NEC followed up on this with the addition of 404.22, which provides a phase-out for the hack of returning current via ground in lieu of neutral:




404.22 Electronic Lighting Control Switches. Electronic lighting control switches shall be listed. Electronic lighting control
switches shall not introduce current on the equipment grounding conductor [ground] during normal operation. The requirement to
not introduce current on the equipment grounding conductor [ground]
shall take effect on January 1, 2020.



Exception: Electronic lighting control switches that introduce current on the equipment grounding conductor [ground] shall be permitted for applications covered by 404.2(C), Exception. Electronic lighting control switches that introduce current on the equipment grounding conductor [ground] shall be listed and marked for use in replacement or retrofit applications only.







share|improve this answer


















  • 4




    But this use of the 12/3 cable for two switches to power two independent lights is perfectly safe and is "grandfathered", right? The owner is under no obligation to bring the wiring up to current code, at least as far as old fashioned switch loops, right?
    – Jim Stewart
    Nov 26 at 11:40







  • 6




    @JimStewart -- it's safe and is grandfathered for existing installs, as long as you aren't trying to shove a smart switch in there :)
    – ThreePhaseEel
    Nov 26 at 12:35






  • 1




    ThreePhaseEel, I think this comment should be the first sentence in your answer.
    – Jim Stewart
    Nov 26 at 13:04







  • 1




    The question asks about both safety and code-compliance, as individual factors, and this answer only addresses one of them. It implies that this is safe (since it used to be to code and the reason for the code change isn’t stated to have been an increase in safety standards or a discovery of a safety flaw in the approach), but it should be stated explicitly, particularly since your comment implies that in addition to concerns about smart switches, this way is also at least saf-er.
    – KRyan
    Nov 26 at 18:49






  • 1




    @supercat, this is one of those things that we don't have to speculate about. Press the sharp spikes of multimeter leads (in ohm mode) into the heads of the two screws of a switch with a plastic switch plate. I just did and got 1 ohm. This was a grounded switch I put in a few years ago..
    – Jim Stewart
    Nov 27 at 1:13











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
17
down vote













There is one safety issue here



It appears that the original installer took the ground wire from the 12/3 cable, looped it around one switch ground screw, then attached it to the other switch ground screw. This grounds the switch yokes fine, but leaves the (metal) box ungrounded save through screw threads. The solution to this is to cut off the existing ground wire with some slack left, then nut it to pigtails to the switch ground screws and a ground screw (10-32) into the provided hole in the back of the box.



While you're at it, you should wrap the white wire with black tape to make it crystal clear to the next bloke looking inside the box that it's hot and not neutral.



As to Code...this used to be OK, but not any longer



Back before the 2011 NEC, an "old style" switch loop like this was permitted by the Code -- a single pole switch only needs always-hot and switched-hot, so a 12/2 cable could be used for a single switch or a 12/3 for a pair of switches sharing a hot feed, as you see here.



However, due to the increasing prevalence of remote-controlled switches, motion sensors, timers, and advanced dimmers, all of which benefit from having a neutral at the switch box to provide power to the electronics inside, the 2011 NEC added 404.2(C) to ensure that the neutral was available for such devices, in lieu of them powering themselves via a hack such as using the ground wire as the return path or trickling their operating current through the load (quoted from the 2017 NEC, save for vernacular terms in [square brackets]):




(C) Switches Controlling Lighting Loads. The grounded
circuit conductor [neutral] for the controlled lighting circuit shall be
installed at the location where switches control lighting loads
that are supplied by a grounded general-purpose branch circuit
serving bathrooms, hallways, stairways, or rooms suitable for
human habitation or occupancy as defined in the applicable
building code. Where multiple switch locations control the
same lighting load such that the entire floor area of the room
or space is visible from the single or combined switch locations,
the grounded circuit conductor [neutral] shall only be required at one
location. A grounded conductor [neutral] shall not be required to be
installed at lighting switch locations under any of the following
conditions:



(1) Where conductors enter the box enclosing the switch
through a raceway, provided that the raceway is large
enough for all contained conductors, including a grounded conductor [neutral]



(2) Where the box enclosing the switch is accessible for the
installation of an additional or replacement cable without
removing finish materials



(3) Where snap switches with integral enclosures comply with
300.15(E)



(4) Where lighting in the area is controlled by automatic
means



(5) Where a switch controls a receptacle load



The grounded conductor [neutral] shall be extended to any switch
location as necessary and shall be connected to switching devices that require line-to-neutral voltage to operate the electronics of the switch in the standby mode and shall meet the
requirements of 404.22.



Exception: The connection requirement shall become effective on January 1, 2020. It shall not apply to replacement or retrofit switches installed in locations prior to local adoption of 404.2(C) and where the
grounded conductor [neutral] cannot be extended without removing finish materials. The number of electronic lighting control switches on a branch
circuit shall not exceed five, and the number connected to any feeder on
the load side of a system or main bonding jumper shall not exceed 25.
For the purpose of this exception, a neutral busbar, in compliance with
200.2(B) and to which a main or system bonding jumper is connected
shall not be limited as to the number of electronic lighting control
switches connected.



Informational Note: The provision for a (future) grounded
conductor [neutral] is to complete a circuit path for electronic lighting
control devices.




and the 2017 NEC followed up on this with the addition of 404.22, which provides a phase-out for the hack of returning current via ground in lieu of neutral:




404.22 Electronic Lighting Control Switches. Electronic lighting control switches shall be listed. Electronic lighting control
switches shall not introduce current on the equipment grounding conductor [ground] during normal operation. The requirement to
not introduce current on the equipment grounding conductor [ground]
shall take effect on January 1, 2020.



Exception: Electronic lighting control switches that introduce current on the equipment grounding conductor [ground] shall be permitted for applications covered by 404.2(C), Exception. Electronic lighting control switches that introduce current on the equipment grounding conductor [ground] shall be listed and marked for use in replacement or retrofit applications only.







share|improve this answer


















  • 4




    But this use of the 12/3 cable for two switches to power two independent lights is perfectly safe and is "grandfathered", right? The owner is under no obligation to bring the wiring up to current code, at least as far as old fashioned switch loops, right?
    – Jim Stewart
    Nov 26 at 11:40







  • 6




    @JimStewart -- it's safe and is grandfathered for existing installs, as long as you aren't trying to shove a smart switch in there :)
    – ThreePhaseEel
    Nov 26 at 12:35






  • 1




    ThreePhaseEel, I think this comment should be the first sentence in your answer.
    – Jim Stewart
    Nov 26 at 13:04







  • 1




    The question asks about both safety and code-compliance, as individual factors, and this answer only addresses one of them. It implies that this is safe (since it used to be to code and the reason for the code change isn’t stated to have been an increase in safety standards or a discovery of a safety flaw in the approach), but it should be stated explicitly, particularly since your comment implies that in addition to concerns about smart switches, this way is also at least saf-er.
    – KRyan
    Nov 26 at 18:49






  • 1




    @supercat, this is one of those things that we don't have to speculate about. Press the sharp spikes of multimeter leads (in ohm mode) into the heads of the two screws of a switch with a plastic switch plate. I just did and got 1 ohm. This was a grounded switch I put in a few years ago..
    – Jim Stewart
    Nov 27 at 1:13















up vote
17
down vote













There is one safety issue here



It appears that the original installer took the ground wire from the 12/3 cable, looped it around one switch ground screw, then attached it to the other switch ground screw. This grounds the switch yokes fine, but leaves the (metal) box ungrounded save through screw threads. The solution to this is to cut off the existing ground wire with some slack left, then nut it to pigtails to the switch ground screws and a ground screw (10-32) into the provided hole in the back of the box.



While you're at it, you should wrap the white wire with black tape to make it crystal clear to the next bloke looking inside the box that it's hot and not neutral.



As to Code...this used to be OK, but not any longer



Back before the 2011 NEC, an "old style" switch loop like this was permitted by the Code -- a single pole switch only needs always-hot and switched-hot, so a 12/2 cable could be used for a single switch or a 12/3 for a pair of switches sharing a hot feed, as you see here.



However, due to the increasing prevalence of remote-controlled switches, motion sensors, timers, and advanced dimmers, all of which benefit from having a neutral at the switch box to provide power to the electronics inside, the 2011 NEC added 404.2(C) to ensure that the neutral was available for such devices, in lieu of them powering themselves via a hack such as using the ground wire as the return path or trickling their operating current through the load (quoted from the 2017 NEC, save for vernacular terms in [square brackets]):




(C) Switches Controlling Lighting Loads. The grounded
circuit conductor [neutral] for the controlled lighting circuit shall be
installed at the location where switches control lighting loads
that are supplied by a grounded general-purpose branch circuit
serving bathrooms, hallways, stairways, or rooms suitable for
human habitation or occupancy as defined in the applicable
building code. Where multiple switch locations control the
same lighting load such that the entire floor area of the room
or space is visible from the single or combined switch locations,
the grounded circuit conductor [neutral] shall only be required at one
location. A grounded conductor [neutral] shall not be required to be
installed at lighting switch locations under any of the following
conditions:



(1) Where conductors enter the box enclosing the switch
through a raceway, provided that the raceway is large
enough for all contained conductors, including a grounded conductor [neutral]



(2) Where the box enclosing the switch is accessible for the
installation of an additional or replacement cable without
removing finish materials



(3) Where snap switches with integral enclosures comply with
300.15(E)



(4) Where lighting in the area is controlled by automatic
means



(5) Where a switch controls a receptacle load



The grounded conductor [neutral] shall be extended to any switch
location as necessary and shall be connected to switching devices that require line-to-neutral voltage to operate the electronics of the switch in the standby mode and shall meet the
requirements of 404.22.



Exception: The connection requirement shall become effective on January 1, 2020. It shall not apply to replacement or retrofit switches installed in locations prior to local adoption of 404.2(C) and where the
grounded conductor [neutral] cannot be extended without removing finish materials. The number of electronic lighting control switches on a branch
circuit shall not exceed five, and the number connected to any feeder on
the load side of a system or main bonding jumper shall not exceed 25.
For the purpose of this exception, a neutral busbar, in compliance with
200.2(B) and to which a main or system bonding jumper is connected
shall not be limited as to the number of electronic lighting control
switches connected.



Informational Note: The provision for a (future) grounded
conductor [neutral] is to complete a circuit path for electronic lighting
control devices.




and the 2017 NEC followed up on this with the addition of 404.22, which provides a phase-out for the hack of returning current via ground in lieu of neutral:




404.22 Electronic Lighting Control Switches. Electronic lighting control switches shall be listed. Electronic lighting control
switches shall not introduce current on the equipment grounding conductor [ground] during normal operation. The requirement to
not introduce current on the equipment grounding conductor [ground]
shall take effect on January 1, 2020.



Exception: Electronic lighting control switches that introduce current on the equipment grounding conductor [ground] shall be permitted for applications covered by 404.2(C), Exception. Electronic lighting control switches that introduce current on the equipment grounding conductor [ground] shall be listed and marked for use in replacement or retrofit applications only.







share|improve this answer


















  • 4




    But this use of the 12/3 cable for two switches to power two independent lights is perfectly safe and is "grandfathered", right? The owner is under no obligation to bring the wiring up to current code, at least as far as old fashioned switch loops, right?
    – Jim Stewart
    Nov 26 at 11:40







  • 6




    @JimStewart -- it's safe and is grandfathered for existing installs, as long as you aren't trying to shove a smart switch in there :)
    – ThreePhaseEel
    Nov 26 at 12:35






  • 1




    ThreePhaseEel, I think this comment should be the first sentence in your answer.
    – Jim Stewart
    Nov 26 at 13:04







  • 1




    The question asks about both safety and code-compliance, as individual factors, and this answer only addresses one of them. It implies that this is safe (since it used to be to code and the reason for the code change isn’t stated to have been an increase in safety standards or a discovery of a safety flaw in the approach), but it should be stated explicitly, particularly since your comment implies that in addition to concerns about smart switches, this way is also at least saf-er.
    – KRyan
    Nov 26 at 18:49






  • 1




    @supercat, this is one of those things that we don't have to speculate about. Press the sharp spikes of multimeter leads (in ohm mode) into the heads of the two screws of a switch with a plastic switch plate. I just did and got 1 ohm. This was a grounded switch I put in a few years ago..
    – Jim Stewart
    Nov 27 at 1:13













up vote
17
down vote










up vote
17
down vote









There is one safety issue here



It appears that the original installer took the ground wire from the 12/3 cable, looped it around one switch ground screw, then attached it to the other switch ground screw. This grounds the switch yokes fine, but leaves the (metal) box ungrounded save through screw threads. The solution to this is to cut off the existing ground wire with some slack left, then nut it to pigtails to the switch ground screws and a ground screw (10-32) into the provided hole in the back of the box.



While you're at it, you should wrap the white wire with black tape to make it crystal clear to the next bloke looking inside the box that it's hot and not neutral.



As to Code...this used to be OK, but not any longer



Back before the 2011 NEC, an "old style" switch loop like this was permitted by the Code -- a single pole switch only needs always-hot and switched-hot, so a 12/2 cable could be used for a single switch or a 12/3 for a pair of switches sharing a hot feed, as you see here.



However, due to the increasing prevalence of remote-controlled switches, motion sensors, timers, and advanced dimmers, all of which benefit from having a neutral at the switch box to provide power to the electronics inside, the 2011 NEC added 404.2(C) to ensure that the neutral was available for such devices, in lieu of them powering themselves via a hack such as using the ground wire as the return path or trickling their operating current through the load (quoted from the 2017 NEC, save for vernacular terms in [square brackets]):




(C) Switches Controlling Lighting Loads. The grounded
circuit conductor [neutral] for the controlled lighting circuit shall be
installed at the location where switches control lighting loads
that are supplied by a grounded general-purpose branch circuit
serving bathrooms, hallways, stairways, or rooms suitable for
human habitation or occupancy as defined in the applicable
building code. Where multiple switch locations control the
same lighting load such that the entire floor area of the room
or space is visible from the single or combined switch locations,
the grounded circuit conductor [neutral] shall only be required at one
location. A grounded conductor [neutral] shall not be required to be
installed at lighting switch locations under any of the following
conditions:



(1) Where conductors enter the box enclosing the switch
through a raceway, provided that the raceway is large
enough for all contained conductors, including a grounded conductor [neutral]



(2) Where the box enclosing the switch is accessible for the
installation of an additional or replacement cable without
removing finish materials



(3) Where snap switches with integral enclosures comply with
300.15(E)



(4) Where lighting in the area is controlled by automatic
means



(5) Where a switch controls a receptacle load



The grounded conductor [neutral] shall be extended to any switch
location as necessary and shall be connected to switching devices that require line-to-neutral voltage to operate the electronics of the switch in the standby mode and shall meet the
requirements of 404.22.



Exception: The connection requirement shall become effective on January 1, 2020. It shall not apply to replacement or retrofit switches installed in locations prior to local adoption of 404.2(C) and where the
grounded conductor [neutral] cannot be extended without removing finish materials. The number of electronic lighting control switches on a branch
circuit shall not exceed five, and the number connected to any feeder on
the load side of a system or main bonding jumper shall not exceed 25.
For the purpose of this exception, a neutral busbar, in compliance with
200.2(B) and to which a main or system bonding jumper is connected
shall not be limited as to the number of electronic lighting control
switches connected.



Informational Note: The provision for a (future) grounded
conductor [neutral] is to complete a circuit path for electronic lighting
control devices.




and the 2017 NEC followed up on this with the addition of 404.22, which provides a phase-out for the hack of returning current via ground in lieu of neutral:




404.22 Electronic Lighting Control Switches. Electronic lighting control switches shall be listed. Electronic lighting control
switches shall not introduce current on the equipment grounding conductor [ground] during normal operation. The requirement to
not introduce current on the equipment grounding conductor [ground]
shall take effect on January 1, 2020.



Exception: Electronic lighting control switches that introduce current on the equipment grounding conductor [ground] shall be permitted for applications covered by 404.2(C), Exception. Electronic lighting control switches that introduce current on the equipment grounding conductor [ground] shall be listed and marked for use in replacement or retrofit applications only.







share|improve this answer














There is one safety issue here



It appears that the original installer took the ground wire from the 12/3 cable, looped it around one switch ground screw, then attached it to the other switch ground screw. This grounds the switch yokes fine, but leaves the (metal) box ungrounded save through screw threads. The solution to this is to cut off the existing ground wire with some slack left, then nut it to pigtails to the switch ground screws and a ground screw (10-32) into the provided hole in the back of the box.



While you're at it, you should wrap the white wire with black tape to make it crystal clear to the next bloke looking inside the box that it's hot and not neutral.



As to Code...this used to be OK, but not any longer



Back before the 2011 NEC, an "old style" switch loop like this was permitted by the Code -- a single pole switch only needs always-hot and switched-hot, so a 12/2 cable could be used for a single switch or a 12/3 for a pair of switches sharing a hot feed, as you see here.



However, due to the increasing prevalence of remote-controlled switches, motion sensors, timers, and advanced dimmers, all of which benefit from having a neutral at the switch box to provide power to the electronics inside, the 2011 NEC added 404.2(C) to ensure that the neutral was available for such devices, in lieu of them powering themselves via a hack such as using the ground wire as the return path or trickling their operating current through the load (quoted from the 2017 NEC, save for vernacular terms in [square brackets]):




(C) Switches Controlling Lighting Loads. The grounded
circuit conductor [neutral] for the controlled lighting circuit shall be
installed at the location where switches control lighting loads
that are supplied by a grounded general-purpose branch circuit
serving bathrooms, hallways, stairways, or rooms suitable for
human habitation or occupancy as defined in the applicable
building code. Where multiple switch locations control the
same lighting load such that the entire floor area of the room
or space is visible from the single or combined switch locations,
the grounded circuit conductor [neutral] shall only be required at one
location. A grounded conductor [neutral] shall not be required to be
installed at lighting switch locations under any of the following
conditions:



(1) Where conductors enter the box enclosing the switch
through a raceway, provided that the raceway is large
enough for all contained conductors, including a grounded conductor [neutral]



(2) Where the box enclosing the switch is accessible for the
installation of an additional or replacement cable without
removing finish materials



(3) Where snap switches with integral enclosures comply with
300.15(E)



(4) Where lighting in the area is controlled by automatic
means



(5) Where a switch controls a receptacle load



The grounded conductor [neutral] shall be extended to any switch
location as necessary and shall be connected to switching devices that require line-to-neutral voltage to operate the electronics of the switch in the standby mode and shall meet the
requirements of 404.22.



Exception: The connection requirement shall become effective on January 1, 2020. It shall not apply to replacement or retrofit switches installed in locations prior to local adoption of 404.2(C) and where the
grounded conductor [neutral] cannot be extended without removing finish materials. The number of electronic lighting control switches on a branch
circuit shall not exceed five, and the number connected to any feeder on
the load side of a system or main bonding jumper shall not exceed 25.
For the purpose of this exception, a neutral busbar, in compliance with
200.2(B) and to which a main or system bonding jumper is connected
shall not be limited as to the number of electronic lighting control
switches connected.



Informational Note: The provision for a (future) grounded
conductor [neutral] is to complete a circuit path for electronic lighting
control devices.




and the 2017 NEC followed up on this with the addition of 404.22, which provides a phase-out for the hack of returning current via ground in lieu of neutral:




404.22 Electronic Lighting Control Switches. Electronic lighting control switches shall be listed. Electronic lighting control
switches shall not introduce current on the equipment grounding conductor [ground] during normal operation. The requirement to
not introduce current on the equipment grounding conductor [ground]
shall take effect on January 1, 2020.



Exception: Electronic lighting control switches that introduce current on the equipment grounding conductor [ground] shall be permitted for applications covered by 404.2(C), Exception. Electronic lighting control switches that introduce current on the equipment grounding conductor [ground] shall be listed and marked for use in replacement or retrofit applications only.








share|improve this answer














share|improve this answer



share|improve this answer








edited Nov 26 at 23:16

























answered Nov 26 at 4:49









ThreePhaseEel

29.3k104490




29.3k104490







  • 4




    But this use of the 12/3 cable for two switches to power two independent lights is perfectly safe and is "grandfathered", right? The owner is under no obligation to bring the wiring up to current code, at least as far as old fashioned switch loops, right?
    – Jim Stewart
    Nov 26 at 11:40







  • 6




    @JimStewart -- it's safe and is grandfathered for existing installs, as long as you aren't trying to shove a smart switch in there :)
    – ThreePhaseEel
    Nov 26 at 12:35






  • 1




    ThreePhaseEel, I think this comment should be the first sentence in your answer.
    – Jim Stewart
    Nov 26 at 13:04







  • 1




    The question asks about both safety and code-compliance, as individual factors, and this answer only addresses one of them. It implies that this is safe (since it used to be to code and the reason for the code change isn’t stated to have been an increase in safety standards or a discovery of a safety flaw in the approach), but it should be stated explicitly, particularly since your comment implies that in addition to concerns about smart switches, this way is also at least saf-er.
    – KRyan
    Nov 26 at 18:49






  • 1




    @supercat, this is one of those things that we don't have to speculate about. Press the sharp spikes of multimeter leads (in ohm mode) into the heads of the two screws of a switch with a plastic switch plate. I just did and got 1 ohm. This was a grounded switch I put in a few years ago..
    – Jim Stewart
    Nov 27 at 1:13













  • 4




    But this use of the 12/3 cable for two switches to power two independent lights is perfectly safe and is "grandfathered", right? The owner is under no obligation to bring the wiring up to current code, at least as far as old fashioned switch loops, right?
    – Jim Stewart
    Nov 26 at 11:40







  • 6




    @JimStewart -- it's safe and is grandfathered for existing installs, as long as you aren't trying to shove a smart switch in there :)
    – ThreePhaseEel
    Nov 26 at 12:35






  • 1




    ThreePhaseEel, I think this comment should be the first sentence in your answer.
    – Jim Stewart
    Nov 26 at 13:04







  • 1




    The question asks about both safety and code-compliance, as individual factors, and this answer only addresses one of them. It implies that this is safe (since it used to be to code and the reason for the code change isn’t stated to have been an increase in safety standards or a discovery of a safety flaw in the approach), but it should be stated explicitly, particularly since your comment implies that in addition to concerns about smart switches, this way is also at least saf-er.
    – KRyan
    Nov 26 at 18:49






  • 1




    @supercat, this is one of those things that we don't have to speculate about. Press the sharp spikes of multimeter leads (in ohm mode) into the heads of the two screws of a switch with a plastic switch plate. I just did and got 1 ohm. This was a grounded switch I put in a few years ago..
    – Jim Stewart
    Nov 27 at 1:13








4




4




But this use of the 12/3 cable for two switches to power two independent lights is perfectly safe and is "grandfathered", right? The owner is under no obligation to bring the wiring up to current code, at least as far as old fashioned switch loops, right?
– Jim Stewart
Nov 26 at 11:40





But this use of the 12/3 cable for two switches to power two independent lights is perfectly safe and is "grandfathered", right? The owner is under no obligation to bring the wiring up to current code, at least as far as old fashioned switch loops, right?
– Jim Stewart
Nov 26 at 11:40





6




6




@JimStewart -- it's safe and is grandfathered for existing installs, as long as you aren't trying to shove a smart switch in there :)
– ThreePhaseEel
Nov 26 at 12:35




@JimStewart -- it's safe and is grandfathered for existing installs, as long as you aren't trying to shove a smart switch in there :)
– ThreePhaseEel
Nov 26 at 12:35




1




1




ThreePhaseEel, I think this comment should be the first sentence in your answer.
– Jim Stewart
Nov 26 at 13:04





ThreePhaseEel, I think this comment should be the first sentence in your answer.
– Jim Stewart
Nov 26 at 13:04





1




1




The question asks about both safety and code-compliance, as individual factors, and this answer only addresses one of them. It implies that this is safe (since it used to be to code and the reason for the code change isn’t stated to have been an increase in safety standards or a discovery of a safety flaw in the approach), but it should be stated explicitly, particularly since your comment implies that in addition to concerns about smart switches, this way is also at least saf-er.
– KRyan
Nov 26 at 18:49




The question asks about both safety and code-compliance, as individual factors, and this answer only addresses one of them. It implies that this is safe (since it used to be to code and the reason for the code change isn’t stated to have been an increase in safety standards or a discovery of a safety flaw in the approach), but it should be stated explicitly, particularly since your comment implies that in addition to concerns about smart switches, this way is also at least saf-er.
– KRyan
Nov 26 at 18:49




1




1




@supercat, this is one of those things that we don't have to speculate about. Press the sharp spikes of multimeter leads (in ohm mode) into the heads of the two screws of a switch with a plastic switch plate. I just did and got 1 ohm. This was a grounded switch I put in a few years ago..
– Jim Stewart
Nov 27 at 1:13





@supercat, this is one of those things that we don't have to speculate about. Press the sharp spikes of multimeter leads (in ohm mode) into the heads of the two screws of a switch with a plastic switch plate. I just did and got 1 ohm. This was a grounded switch I put in a few years ago..
– Jim Stewart
Nov 27 at 1:13


















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