Volume 13 Issue 1
July 2015    
ballast - A device required by electric-discharge light sources such as fluorescent or HID lamps to regulate voltage and current supplied to the lamp during start and throughout operation. compatible ballasts - An abbreviated list of common ballasts that will provide the necessary circuitry for a photosensor to operate correctly. Other ballasts may also be compatible; contact the photosensor manufacturer for details. continuous dimming - Control of a light source's intensity to practically any value within a given operating range. capacitor - A device used in electric circuitry to temporarily store electrical charge in the form of an electrostatic field. In lighting, a capacitor is used to smooth out alternating current from the power supply. time delay range - For motion sensors, the range of time that may be set for the interval between the last detected motion and the turning off of the lamps. lamp - A radiant light source. luminaire - A complete lighting unit consisting of a lamp or lamps and the parts designed to distribute the light, to position and protect the lamp(s), and to connect the lamp(s) to the power supply. (Also referred to as fixture.) frequency - The number of cycles completed by a periodic wave in a given unit of time. Frequency is commonly reported in cycles per second, or hertz (Hz). electromagnetic interference (EMI) - The interference of unwanted electromagnetic signals with desirable signals. Electromagnetic interference may be transmitted in two ways: radiated through space or conducted by wiring. The Federal Communications Commission (FCC) sets electromagnetic interference limits on radio frequency (RF) lighting devices in FCC Part 18. electronic ballast - A ballast that uses electronic components instead of a magnetic core and coil to operate fluorescent lamps. Electronic ballasts operate lamps at 20 to 60 kHz, which results in reduced flicker and noise and increased efficacy compared with ballasts that operate lamps at 60 Hz. illuminance - The amount of light (luminous flux) incident on a surface area. Illuminance is measured in footcandles (lumens/square foot) or lux (lumens/square meter). One footcandle equals 10.76 lux, although for convenience 10 lux commonly is used as the equivalent. dimming ballast - A device that provides the ability to adjust light levels by reducing the lamp current. Most dimming ballasts are electronic. power - The power used by a device to produce useful work (also called input power or active power). In lighting, it is the system input power for a lamp and ballast or driver combination. Power is typically reported in the SI units of watts. photosensor - A device used to integrate an electric lighting system with a daylighting system so lights operate only when daylighting is insufficient. lux (lx) - A measure of illuminance in lumens per square meter. One lux equals 0.093 footcandle. nadir - In the lighting discipline, nadir is the angle pointing directly downward from the luminaire, or 0. Nadir is opposite the zenith. driver - For light emitting diodes, a device that regulates the voltage and current powering the source. photovoltaic (PV) - Photovoltaic (PV) cells produce electric current from light energy (photons). PV cells are joined to make PV panels. hysteresis - The dependence of the output of a system not only on its current input, but also on its history of past inputs. The electric light level set by a photosensor with hysteresis, for a certain photocell input signal, depends on whether that photocell signal is increasing or decreasing. Hysteresis provides stable operation in switching photosensors but is undesirable in dimming photosensors.


The National Lighting Product Information Program (NLPIP) investigated the performance of wireless occupancy sensors and photosensors, focusing on control systems designed for a single room in a commercial building such as an office, classroom, or conference room. NLPIP tested wireless and wired control systems from Lutron, Leviton, and WattStopper because these are the brands of controls most frequently selected by specifiers according to an NLPIP survey. The investigation included:

  • Occupancy sensor and photosensor features and performance
  • Wireless communication performance
  • Compatibility with lighting products
  • Energy harvesting and storage capabilities
  • Capital costs of control systems

NLPIP found that:

  • Wireless occupancy sensors from the evaluated brands were available with only passive infrared detection technology. The lack of wireless ultrasonic and dual technology occupancy detectors should be taken into consideration where furniture may block line-of-sight motion detection.
  • The wireless occupancy sensors and photosensors tested had similar performance as equivalent wired sensors from the same manufacturer.
  • NLPIP found little difference in the occupancy sensors’ and photosensors’ performance compared to that seen in previous NLPIP studies of these types of products.
  • The wireless communication was robust in a typical office environment.
  • Operation of electronic ballasts or drivers could be compromised for controllers that don’t make use of a neutral wire and/or are installed in a switchbox without a neutral wire.
  • Photovoltaic energy harvesting by the tested occupancy sensors is likely to be insufficient at some ceiling locations. Installing a battery in the sensor will circumvent this problem. 
  • The tested wireless occupancy sensor systems had 54 to 128% higher capital costs than the equivalent wired systems from the same brand.


Automated lighting controls such as occupancy sensors and photosensors can be an effective way of reducing energy use. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Energy Standard for Buildings 90.1-2010 and the National Energy Code of Canada for Buildings 2011 (NECB) require automated lighting control sensors in more rooms than earlier building codes. Specifiers evaluating lighting control products to meet these needs may consider wireless lighting control options, which are often claimed to reduce installation costs compared with wired options.

The National Lighting Product Information Program (NLPIP) compared the performance and the features of wireless lighting controls with equivalent wired controls, focusing on systems designed for a single room in a commercial building, such as an office, classroom, or conference room. NLPIP did not investigate more complex control systems that store pre-programmed lighting scenes, control a whole building, or communicate with one another on mesh networks.

Figure 1 illustrates the components of wired and wireless control systems for single rooms. Components include a sensor, controller (which may be called an actuator, relay, or power pack), and wall-mounted switch or dimmer. The wireless controller is sometimes integrated with the switch or dimmer into one component that replaces an existing light switch.

The sensor is usually mounted on a ceiling or a luminaire or high on a wall. Because a wireless sensor lacks a wired connection, it must be self-powered with a battery and/or by energy harvesting (by using a photovoltaic module).

In wired systems, the sensor device is physically connected to the controller and light switch. In wireless systems, the controller communicates with the sensor (and possibly the light switch) via radio frequency (RF) signals. Because the controller is always connected by wires, an electrician is needed for installation, whether it uses wired or wireless communication.

Figure 1. Wiring schematic diagrams. (a.) shows the lighting system without automated controls; (b.) shows an example of a wired control system, representative of the wired control systems tested by NLPIP; (c.) shows an example of a wireless control system with the manual switch and controller integrated into one device, representative of the Leviton and WattStopper systems tested by NLPIP; (d.) shows a wireless control system with a separate manual switch and controller, representative of the Lutron system tested by NLPIP. (The manual switch was not tested.)

Figure 1

NLPIP identified some potential advantages of wireless lighting controls, compared with wired versions:

  • decreased installation labor for wiring
  • increased ability to add controls in spaces that don't have easy access to ceiling or wall cavities and surface conduit isn't desired
  • increased ability to reposition sensors or add more sensors for improved coverage if needed

NLPIP identified some potential disadvantages of wireless lighting controls, compared with wired versions:

  • lack of availability of ultrasound or dual technology occupancy sensors
  • higher capital cost
  • potential for wireless communication problems, such as electromagnetic interference (EMI)
  • potential for sensor to stop operating due to lack of energy

NLPIP first identified manufacturers of wireless lighting controls and found that products were available in the U.S. from more than 40 companies at the time of the study. NLPIP then surveyed lighting specifiers not identified with manufacturers to identify three brands to test. The results showed that the three brands of wireless lighting controls most frequently evaluated or selected by the 152 specifiers who responded were Leviton, Lutron, and WattStopper.

NLPIP then consulted these three brands’ marketing literature and sales representatives to determine the equipment to purchase. NLPIP purchased products suitable for automatically controlling the lighting within a single room in order to meet energy codes. Equipment was not sought to provide whole-building control, programmable scenes, or other features. For each brand, NLPIP attempted to purchase four sets of equipment: wired and wireless occupancy sensors and photosensors. WattStopper did not offer a wireless photosensor at the time of purchasing, so no WattStopper photosensors were tested. Because the wireless occupancy sensors were exclusively passive infrared (PIR) rather than ultrasound or dual technology, NLPIP specified PIR wired sensors for comparison purposes. The products that NLPIP tested are shown in Table 1.

Table 1. Equipment tested by NLPIP (click on photos for larger image).

Brand Sensor Connection Occupancy Sensor Photosensor
Leviton Wired
Sensor: OSC04-RIW

Sensor: ODC0P-00W

Controller: OSP20-ND0

Controller: MZD20-102
Sensor: WSC04-IRW

Sensor: WSCPC-W

Controller: WSS10-GUZ

Controller: RF WST05-10
Lutron Wired
Sensor: LOS-CIR-450-WH

Sensor: EC-DIR-WH

Controller: PP-120H

Controller: QSN-4T16-S
Sensor: LRF2-OCR2B-P-WH

Sensor: LRF2-DCRB-WH

Controller: RMJ-ECO32-DV-B

Controller: RMJ-ECO32-DV-B
WattStopper Wired
Sensor: CI-200-1
WattStopper photosensors were not tested because, at the time of purchase, WattStopper did not sell a wireless photosensor.

Controller: BZ-150
Sensor: EOPC-100

Controller: EOSW-101

NLPIP performed tests to investigate the following characteristics of wireless lighting controls:

The lighting controls were purchased in January and February 2014 and were tested in March through June 2014. NLPIP's results are based on tests of one sample of each product. Variation between samples was not investigated.

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