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Motion Sensor Needs Neutral, but none in box

Posted by reastland (My Page) on
Sun, Nov 6, 11 at 17:19

I'm trying install a motion sensing switch in a 3-way configuration. I'm just replacing an existing switch, so the wiring is straightforward. However, the new switch requires a connection to a neutral wire, but there isn't a neutral wire in the box. Just a load, two travelers, and a ground. I don't know how the box was originally wired, but sometimes electricians take shortcuts to save on wire, and this appears to reveal one of those situations.

So, what options do I have? Can I connect the neutral wire on the new switch to the ground wire? There is an outlet (that is wired on a different circuit) nearby. Can I wire into that neutral wire? I don't like either of those options, but they appear to be my only ones, short of taking the three-way configuration down to a single-pole or just giving up on this altogether.

I appreciate any advice, but I respectfully ask that only those who truly know attempt to respond to this.

Thanks.


Follow-Up Postings:

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RE: Motion Sensor Needs Neutral, but none in box

There was most likely no short cut. The codes didn't require neutrals to be run to switches that didn't require it. If you're not using the "three way" aspect of things anymore, you can probably backfeed the neutral through one traveller and use the other one as the switched leg.


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RE: Motion Sensor Needs Neutral, but none in box

Thanks. The reason that I refer to it as a short cut is that, while perfectly appropriate for the switch installed at the time, it is less than ideal for many other applications. It can't be that much more expensive to run a 5-wire cable than it is to run a 4.

What about my idea of jumping a neutral over to the other junction box (on a different circuit)? Is that safe? Code compliant?

You are probably right that single-pole is where I will wind up, but I'm wondering if there are any creative yet safe solutions.

Thanks for your advice.


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RE: Motion Sensor Needs Neutral, but none in box

"It can't be that much more expensive to run a 5-wire cable than it is to run a 4."

Not at all, 14/4 costs about twice what 14/3 costs. It is not uncommon at all to not have a neutral at switch locations. That is until the latest code is followed, not sure if it is in 08 or 11 but switches have to have a neutral wire present. Most people will run power to the 1st switch, 14/3 to the next, and 14/2 to the light rather than bother with 14/4. Switch loops will use 14/3 and cap off the unused white in the box.

And definitely a big no on grabbing a neutral from a random circuit. Someone working on the other circuit with the power off would get a nasty surprise opening the neutral connection on what they think is a dead device. Plus it is prohibited by code for other reasons as well.


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RE: Motion Sensor Needs Neutral, but none in box

Thanks for the advice. That's what I thought would be the answer.


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RE: Motion Sensor Needs Neutral, but none in box

Switch loops (without a neutral) were absolutely standard issue, and still are. They are NOT a "short cut" at all.
Running an extra cable to a 3-way switch loop would NOT enter the mind of anyone running it.
Switches requiring a neutral are a relatively new thing, and 14/4 or 14/2/2 have only been around a few years.

My suggestion is to find a different switch that does not require a neutral.


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RE: Motion Sensor Needs Neutral, but none in box

Unless your installation was convered by NEC 2011. It's now required to provide the neutral switch box. As stated, almost certainly when the house was constructed there was not only no requirement to do so, and common practice was to not do so. It's only the prevalence of smart switches like the poster is now trying to install and other home automation stuff that caused the code to change (or under specific request of the customer such as when I had my house built).


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Required in NEC 2011, not in earlier

Unless your installation was convered by NEC 2011. It's now required to provide the neutral switch box. As stated, almost certainly when the house was constructed there was not only no requirement to do so, and common practice was to not do so. It's only the prevalence of smart switches like the poster is now trying to install and other home automation stuff that caused the code to change (or under specific request of the customer such as when I had my house built).


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RE: Motion Sensor Needs Neutral, but none in box

Some of the earlier devices included in their instructions a description of how to deal with installations that do not prove a neutral. If the device is UL Listed, following the included instructions for that specific device is permissible (Required) under the NEC. I will not elaborate further on the possibilities that might be involved in those instructions. Read the instructions carefully.


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RE: Motion Sensor Needs Neutral, but none in box

The same issue seems to exist for timers etc - the permanent mount ones. They too insist on their own neutral, but I guess that's why the code changed.


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