Bdtyktl

I wish to have a motion sensor on the lights in my garage, but I also want to have an override switch that works normally, and does not require a specific pattern to toggle the override in the sensor.

Is this circuit workable?

                / Wall switch

        +------0   0-----+

        |                |

--Phase-+-----Sensor-----+-------+

               |  |             Lights

--Neutral------+--+--------------+   |

--Earth------------------------------+

The lights are 4x flourescent tubes in two double fittings, but I may add more later. Or may replace with LED fittings if that helps.

Essentially I'm trying to replicate the function of an Occupancy Sensor wall plate, like this:

For some reason these aren't available in New Zealand. Voltage is 230 VAC at 50Hz.

The main reasons for concern are that:

• the sensor will have live voltage on both sides even when the sensor is off.


• the lights will not be isolated from power simply by turning off the wall switch. Adequate labelling at the lights should cover this
  ("WARNING DUAL SUPPLY! Disable sensor AND check for voltage before servicing.")
  
  

Related to but not a dupe of

• How should dual motion sensors be connected?


• multiple motion detectors wired together

As I discuss in the answer you linked, that is fine. There are some minor glitches in your drawing, but nothing worrisome. Try

                / Wall switch

        +------0   0-----+

        |                |

--Phase-+-----Sensor-----+-------+

                 |              Lights

--Neutral--------+---------------+

(ground removed for clarity, actually it's needed at all devices assuming NZ code does not delete this popular requirement). And this is strictly a schematic, the wiring method must be such that currents balance in each cable or conduit.

A quality, modern motion sensor with its own neutral isn't going to have a problem with its LOAD hot being externally hottified by a switch or other motion sensor.

A maintainer, especially one who has looked around the room and observed motion sensors, should be shutting off power at the circuit breaker. I have no sympathy for someone who wants to work the circuit "hot", unless NZ Code has a variation that says I should. For all the servicer knows, it's wired with a switched neutral.

I've done this. Works great. A switch and motion sensor in parallel. It also works with two motion sensors. Only thing is that highest takes precedence, in other words if the motion sensor turns the light on the switch is not able to turn it off. I tolerate this issue.

Works great.

good luck.