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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 Mar 10 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 Mar 10 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 Mar 11 at 0:09
    
@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 Mar 11 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 Mar 11 at 11:15
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4 Answers 4

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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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Thank you. I missed this in the instructions. –  Speedy Petey Mar 11 at 11:33
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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 Mar 11 at 10:44
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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 Mar 11 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 Mar 11 at 11:21
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