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My house was built in early 1950's and all electrical switches do not have a ground. This was found out with an electrician when I asked them to install Lutron Maestro, but it would not power on since there was no ground to connect it to.

His suggestion was to find a motion sensing light switch that did not need ground, but he could not make a recommendation off-hand.

Do motion sensing light switches that do not require ground exist? Or do I have to build/rig them somehow. Unfortunately, due to cost, I cannot afford to add ground wires to the areas of the house that I need these at.

EDIT The electrician connected the Meastro unit then attempted to turn it on. Pressing the button or moving in front of the sensor did not turn it on. He also attempted to connect the unit's ground to either neutral or hot, but did not work either (I can't recall which). Guess I have to spend the loot and run ground wire :(

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    An equipment ground has nothing to do with the functionality of switches and devices. It is a safety backup (for lack of a better term). Switches, receptacles, even GFIs will function fine without a ground. That said, a proper ground adds substantially to the safety of an electrical system. For replacement purposes though you can replace switches even without a ground. For something like an occupancy sensor or motions detector if the manufacturer's instructions say it must be grounded then it must be grounded.
    – Speedy Petey
    Commented Mar 10, 2014 at 22:00
  • I am not sure what your electrician did or found that caused him to say the ground was the reason it was not working.
    – Speedy Petey
    Commented Mar 10, 2014 at 22:01
  • WOW!! (after reading the edit) If this clown attached the ground to either the neutral or the hot(!!!) he was NO electrician. I can assure you that. I can almost guaranty you he killed the device by doing this. Please, before you go any further, find someone who knows what they are doing to look at this.
    – Speedy Petey
    Commented Mar 11, 2014 at 0:09
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    @SpeedyPetey Some devices such as timers, dimmers, etc. require power to operate. In most cases a neutral is not present in a switch box, but one is required by the device. The geniuses that manufacture these devices have found a solution for this problem, and actually use the grounding conductor as a way to power the device. If a device like this does not have a grounding conductor attached, it will not operate.
    – Tester101
    Commented Mar 11, 2014 at 10:41
  • @SpeedyPetey I agree that the equipment grounding conductor should never carry current, however, device manufacturers don't have the same views. See my answer below, with wiring diagrams.
    – Tester101
    Commented Mar 11, 2014 at 11:15

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Occupancy sensors, timers, dimmers, and other "smart" switches often are required to be independently powered. If you look at this diagram from the devices documentation (PDF), you'll see that there are three ways this requirement is achieved.

Selection Matrix

Neutral Wire Required

The first method, is to simply require a neural wire. In this configuration, the device draws power using the ungrounded (hot) conductor and grounded (neutral) conductor. It also has a separate switched conductor, that it uses to control the load.

This setup would be wired like this...

Neutral Wire Required Wiring

Minimum Load Required

This method draws power using the ungrounded (hot) conductor, and the switched conductor. So the device is actually in line with the load.

This setup is wired like this...

Load Required Wiring

Ground Wire Required

This method draws power using the ungrounded (hot) conductor, and the grounding conductor. It's wired similar to the Neutral Required devices, however, it uses the grounding conductor instead of the grounded conductor. This means that there will be a small amount of current on the grounding conductor, and that the grounding conductor is required for the device to operate.

This setup would be wired like this...

Ground Required Wiring

Notice there's a bare, and green wire connected to ground in this diagram.

tl;dr

Your device

The device you're using (MS-OPS5M-XX) requires a ground to operate, according to the documentation.

Solutions

Install grounding conductors

One solution, would be to install a grounding conductor with this circuit. This will likely require quite a bit of work, and might be quite costly.

Install a grounded conductor

It may be possible to extend a grounded (neutral) conductor from the light to the switch box, which could then be used to power the device. In this case you'd have to purchase a different device (one that requires a neutral rather than a ground).

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    Dumb question: If I understood this correctly, a switch that requires neutral will have a small amount of current (enough to power motion sensor) from hot to neutral. A switch that requires ground will have a small amount of current from hot to ground. So what's the harm in connecting the switch's neutral to ground in the former? Load is still going to its neutral which is separate. Wouldn't that have a similar amount of current (i.e. non life-threatening) going to ground like the latter? I'm probably misunderstanding something...
    – Nelson Rothermel
    Commented Oct 15, 2015 at 22:57
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    @NelsonRothermel Because you're not supposed to have any current on the grounding conductor. I'm not sure how the manufacturer gets away with it.
    – Tester101
    Commented Oct 15, 2015 at 23:45
  • Agreed, the grounding conductor shouldn't have any current, but if that's what the manufacturer is doing then it sounds like they're just connecting neutral to ground internally and then just exposing the one wire. That didn't seem right to me, so I just needed a sanity check. The only other thing I can think of is they have a capacitor/battery that charges when there is load. Of course if the switch is off for a long time it would discharge, so they could have a SPNC switch to auto-charge (and as a side effect turn on the light). Trying to reason this out, otherwise it seems wrong.
    – Nelson Rothermel
    Commented Oct 16, 2015 at 0:39
  • @NelsonRothermel They could be trickling a small current through the load, which wouldn't be enough to turn on incandescent bulbs.
    – Tester101
    Commented Oct 16, 2015 at 1:07
  • I have seen switches that are compatible with CFLs even, so it seems they are using ground. Funny how they don't mention there is a safety issue and may not be code compliant. Here's an interesting article from 2008 which is very informative: wattstopper.com/~/media/8B8F29033C374742B933AB9668DB15D2.ashx "certain products that leak current to ground are considered to be code-compliant.... these small amounts of current add up and can become significant." NEC also usually requires a neutral conductor since 2011: sensorswitch.com/Literature/WP_WSD_NGX.pdf
    – Nelson Rothermel
    Commented Oct 16, 2015 at 12:44
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I think you probably mean the switch didn't have a neutral (which is connected to ground but not the same thing as "ground").

Standard light switches are either open or closed, and so they only have the incoming hot wire and the outgoing hot wire that are either connected ("on") or disconnected ("off").

If you have a switch with additional features that need electricity there are two options:

  1. Add a neutral wire to the switch so that the switch can consume some extra current from the incoming hot and return it via neutral.
  2. Draw a very small amount of current inline with the main light. This means that the light is always on, just very dim when the switch is in the "off" position. This is an older technique that eliminates the requirement for a neutral, however A) It does not work with fluorescent or LED bulbs, B) there is constantly electricity flowing through the light, and C) there is a limit to how much electricity can be used by the device.

Sounds like your chosen motion sensor is of the first type, i.e. it requires a neutral. Your electrician is suggesting the second type. There may or may not be such a sensor.

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    Some devices actually use the grounding conductor as a grounded conductor, meaning they leak current to ground in order to power themselves. I'm guessing this is one of those devices, in which case it will not operate without a ground connected.
    – Tester101
    Commented Mar 11, 2014 at 10:44
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Can you take the cover off a switch and take a photo to show us?

I rewired my 1959 house in 2011. Although the switches and receptables were not grounded, there was a ground in every box. (Although electrical code can vary by jurisdiction, I would be surprised if your electrical boxes were not grounded.)

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You need a ground. Neutrals aren't always in a switch box (depends on how the wires are ran). You might be able to run a 14/2 from the switch box to the nearest receptacle box and splice the ground connection in the receptacle to your switch. Cap off the white an black in that 14/2. As long as the ground going to the receptacle is on the same system that is providing power to switch your good. Might not be pretty but it will work.

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Looking at the instructions for this unit I see no reason it cannot be used in a replacement application where no ground is present.

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    I didn't down vote you, but check the wiring diagrams for the model the OP is using (MS-OPS5M-XX). It shows both a bare and green wire connected to ground.
    – Tester101
    Commented Mar 11, 2014 at 11:17
  • The OP said "He also attempted to connect the unit's ground to either neutral or hot... (I can't recall which)". This to me means the OP isn't exactly clear what the Electrician did, not that there's a neutral present. I'm guessing the Electrician connected the green wire to the load wire, but who knows.
    – Tester101
    Commented Mar 11, 2014 at 11:21
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Using the green wire which comes out of the switch, attached to the neutral is an acceptable method to get this type of switch to function. Honestly, if anybody has violated safety rules, it's the manufacturer of the switch. As a current carrying conductor, this should be a neutral connection, and a white wire respectively. Green/ground connections should only be intended for a safety current path, not for the operation of the switch. Since there is no exposed ground or neutral with this switch, there is no risk of contact to a live conductor when installed. I don't see how this switch would pass leakage current testing with UL or any other testing organization.

For those saying "Your license should be revoked, and you should be thrown out of school.", get your panties out of a twist, he's right, the manufacturer is the guilty party here.

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  • Installing equipment that you know to be defective and/or dangerous, is called negligence. You can blame the manufacturer all you want, but at the end of the day, you have to take responsibility for your actions.
    – Tester101
    Commented Mar 21, 2016 at 14:31
  • @Tester101 Yes, correct but then the right option seems to be not to use those switches at all which are utilizing the safety ground for their functional currents?
    – curious_cat
    Commented Jul 27, 2016 at 15:24
  • @curious_cat Yes, the best option is to avoid those types of devices.
    – Tester101
    Commented Jul 27, 2016 at 15:29
  • @Tester101 But given a device with a ground wire what would be a good way for a consumer to know whether the device is truly using the ground connection as intended i.e. only as a safety ground or whether it abuses the ground by misusing it for a operational ground? Is there a black-box way to determine this? Or only by using a circuit diagram?
    – curious_cat
    Commented Jul 27, 2016 at 15:35
  • @curious_cat If you have an ammeter that's sensitive enough, you should be able to measure the current on the "ground".
    – Tester101
    Commented Jul 27, 2016 at 15:55
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More than likely there is a ground wire or neutral at least "passing" threw that switch box. Probably wire nutted and tucked away in the back. I have an occupancy sensor that requires a neutral, my old house only has the ground and hit in the swotch box. I'm a licensed electrician and major in electrical engineering. Think about it. The neutrals and grounds are all tied down at the same buss in the panel. So I tied my neutral of the switch to the ground in back of box and wham its on working fine.

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  • Electrically the device will function the same if you connect it to a ground wire or a neutral. However, using the ground in situations where you need a neutral runs the risk of electrocuting someone if there's ever an open neutral and you become the path between the grounded body of an appliance and a true ground.
    – BMitch
    Commented Jul 8, 2015 at 0:23
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    Your license should be revoked, and you should be thrown out of school. By using the grounding conductor as a "neutral", you've made the grounding conductor a current carrying conductor. There's now current flowing through all the metal objects that the conductor is in contact with, including boxes, frames, etc.
    – Tester101
    Commented Jul 8, 2015 at 11:40
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People in here are talking about these electronic switches and the grounds that are on them as though the ground is a current-carrying conductor when that is definitely not the case. The reason there is a ground in many electronic circuits is that it is used as a zero reference point for the operation of electronic components that I will not get into discussing. Many electronic circuits do not behave correctly without the ground connection. These are not simple electric switches, there are some complicated electronics involved that require the ground point.

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    You're conflating the electronics definition of "ground" as a zero reference point with what US electricians call "ground" (really, a protective earth)
    – ThreePhaseEel
    Commented Nov 18, 2021 at 4:54
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The neutral is required to power the motion sensor and solid state timer. It cannot function without at least 1 hot and one neutral. Since all neutrals should be joined in the breaker box to one terminal block, any neutral in the house will work. Also (while not recommended, by the NEC you could wire neutral to anything in the house that's grounded, plumbing, electrical box itself, although being the house was built in the fifties the NEC wasn't as strict so finding a bonded/grounded surface may be difficult. But you have to provide a path for the neutral wire in the switch to get back to the neutral/ground terminal in the breaker box, one way or another to get it to be functional.

Small print is, (The NEC requires that no ground wire, may be used as a current carrying conductor.) Although the ground wire ultimately meet the neutral wires they shouldn't have any current. But on the other end probably most of the stuff in your house doesn't comply with modern NEC anyway...

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    Connecting a "neutral" conductor to the grounding conductor or any other grounded item in the house is not safe, as it will allow current to flow through the conductor. It is also not safe to use a "neutral" from a different circuit, as this can lead to an overloaded conductor.
    – Tester101
    Commented Oct 1, 2014 at 10:04

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