Selecting Effective Lighting Control White Paper – Rockwell Automation, WHITE PAPER Selecting Effective Lighting Control, Bulletin 500 Lighting Contactors This paper examines different types of lighting controls and home automation, X-10, Insteon, Z-Wave, UPB, RadioRA 2. Provides guidelines that may help in selecting the controls to suit individual needs with particular emphasis on lighting contactors.

Bulletin 500 Lighting Contactors

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Bulletin 500 Lighting Contactors

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Table of

Contents

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Categories of Lighting Contactors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Feeder Disconnect Type and Combination Lighting Contactors . . . . . . . . . . . . . . . . . . 5

Multi-Pole Lighting Contactors for Branch Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Low-Voltage Relays for Selective Lighting Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Application Considerations for UL 67 Listed Panelboards and UL 508 . . . . . . . . . 10

Lighting Control Methods and Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Control Modules. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Two-Wire Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Three-Wire Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Start-Stop Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Control Line Runs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Timing Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Sensors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Industrial Computer/Programmable Controller Based Control Systems. . . . . . . . 18

Level Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Selection Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Size of Individual Lighting Area . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Facility Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Existing Facilities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

European Common Market. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Conclusion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Bulletin 500 Lighting Contactors

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Introduction In the past decade, there have been many improvements in the control of lighting, for

residential, commercial, institutional, and industrial facilities. This has resulted in more

efficient use of electricity, greater utilization of daylight, and more versatile, automated,

and convenient controls. Such control devices include contactors, relays, timers, sensors,

operator interface graphic terminals, programmable controllers, and industrial computerbased

control systems that may be utilized in diverse on-off and variable level control

schemes. This white paper discusses different types of lighting controls and provides

guidelines that may help in selecting the controls to suit individual needs, with particular

emphasis on lighting contactors.

Categories of

Lighting

Contactors

In its simplest form, on-off lighting control can be a manually operated switch located on a

wall, a timer, a relay mounted in a lighting fixture, separately mounted lighting contactors,

or panelboards containing lighting contactors. Manually operated switches are often used

in residential, commercial, and institutional facilities. However, the trend is toward the use

of remote electrically-operated lighting contactors, programmable controllers, and wall

mounted operator interface graphic terminals (e.g., Allen-Bradley PanelView™) to facilitate

better energy management and supervisory control. To enhance ease of field conversions

and servicing, many lighting contactors are designed to a modular platform with

interchangeable contact blocks and coils.

Lighting contactors can be divided into three general categories: feeder disconnect type

2-, 3-, and 4-pole lighting contactors rated up to 2250 A to control large blocks of load,

multi-pole lighting contactors with as many as 12 poles rated 20…30 A for multi-branch

circuit control, and industrial relays rated 20…35 A with low-voltage control for individual

branch circuit or luminaire control. Lighting contactors are typically electrically held,

mechanically held, or permanent magnet latch type, thus lending themselves to many

forms of automatic control.

PanelView is a trademark of Rockwell Automation, Inc.

Bulletin 500 Lighting Contactors

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Feeder Disconnect Type and Combination Lighting Contactors

Feeder disconnect type lighting contactors are used for turning large blocks of lights on and off.

They are available in both NEMA and Definite Purpose type designs. Though available in sizes

up to 2250 A, the more popular sizes range from 30…225 A because the trend has been to use

them to control full-bus and split-bus lighting panelboards. See Figure 1.

Figure 1. Allen-Bradley Bulletin 500L (10…2250 A top wiring electrically-held),

500FL (20…300 A feed-through wiring electrically-held), 500LP (20…300 A top

wiring permanent magnet latching), and 400 Definite Purpose Contactor

Whenever lighting is being distributed over a wide area, two-pole, three-pole, and four-pole

lighting contactors can help provide safety, economy, and convenience. Since small conductors

can be used for control stations, and an almost unlimited number of stations can be used to

control each lighting contactor, the electrical designer can be liberal with the number of

multiple control stations used.

Shown in Figure 2 is a typical illustration of a three-wire control installation. In this instance a

three-pole Lighting Contactor is being controlled from three (3) remotely located (three-position,

momentary center off) control stations. Typically applied for switching large blocks of lights at

the panelboard these types of lighting contactors can have ratings from 30…225 A.

Figure 2. Typical Illustration of a Three-Wire Control Installation

Bulletin 500L

Bulletin 500FL

Bulletin 500LP

Bulletin 400-DP

Bulletin 500 Lighting Contactors

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Typical of the previous installation in Figure 2, feeder disconnect type lighting contactors

might be a large high-rise office building. As an example, four 225 A lighting contactors

could provide on-off switching of the four zones of lighting on each floor of a high-rise

building. The lighting contactors could, in turn, be controlled by one or more master

controllers. Feeder disconnect type lighting contactors can be provided as open type or

enclosed.

Combination lighting contactors are available for applications that require combining

switching and overcurrent protection in the same enclosure. Combination lighting

contactors may be applied for industrial, highway and area lighting applications or where a

lighting circuit may have to be disconnected for periodic maintenance. See Figure 3.

Figure 3. Allen-Bradley Bulletin 502L (with disconnect switch) &

503L (with circuit breaker) Combination Lighting Contactors

Bulletin 502L Bulletin 503L

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Multi-Pole Lighting Contactors for Branch Circuits

Today’s compact, multi-pole, lighting contactors are available up to 12 poles, with contacts

rated at 20…30 A for branch circuits. See Figure 4.

Figure 4. Allen-Bradley Bulletin 500LG Lighting Contactor (electrically held), 500LC Lighting

Contactor (mechanically held), and 100L Lighting Contactor (electrically held)

The compact multi-pole lighting contactors that are electrically held require a continuous

control voltage to maintain their position. Electrically held lighting contactors change position

and disconnect power to lights and/or general loads during sustained reduction or complete

loss of control voltage. This change of state during loss of power is critical for applications or

processes that require inspection prior to start up. Thus, electrically held lighting contactors are

well suited where protection is needed against automatic restart after a power failure or where

reliability to a control function is critical to safety.

The compact multi-pole lighting contactors that are mechanically held require only a

momentarily applied current to either close or open. This enables the lighting contactor to be

controlled by:

1. Manually operated, three-position, momentary contact switches with the center off

positions.

2. Auxiliary relays or solid-state modules that operate as a function of photoelectric and

occupancy sensors.

3. Timers with a single-pole, double-throw contact. Single-throw contacts can be utilized if a

two-wire control module is furnished.

4. Energy management systems.

Mechanically held lighting contactors do not change position and disconnect the lights during a

momentary drop, sustained reduction or complete loss of control voltage. Such contactors do

not require a continuous control voltage to maintain their position. Because the operating coil is

not continuously energized, coil hum and continuous coil power consumption are eliminated,

thus avoiding background noise and saving energy at the same time.

Bulletin 500LG Bulletin 500LC Bulletin 100L

Bulletin 500 Lighting Contactors

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Magnetically held, 20 A, multi-pole, lighting contactors are also used for lighting control.

To provide fail-safe lighting in the event of loss of control power, Form C relays with

normally closed contacts that carry the lighting load can be used. However, contact

configuration and reduced contact pressure of normally closed contacts often limit the

ability to carry fault currents or meet UL requirements.

Multi-pole, double-throw, lighting contactors are also available. These can be used to

select either of two lighting levels, e.g., day lighting or night lighting, from a common

power source.

From an energy conservation point-of-view, controlling a specific number of branch circuits

or luminaires (2…12) rather than large blocks of lighting allows more design flexibility and

customizing for the application. The latest multi-pole lighting contactors are available with

optional solid-state control modules that provide convenient interfacing with various

control systems. These will be discussed later.

Today’s multi-pole lighting contactors are of shallow construction to accommodate

mounting in panelboards or separate mounting in 4-inch stud-construction walls. They can

be designed to withstand fault currents up to 22,000 A, symmetrical rms.

Bulletin 500 Lighting Contactors

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Low-Voltage Relays for Selective Lighting Control

Low-voltage relays are usually single pole and used for individual branch circuit or luminaire

control. These single-pole low-voltage relays are available with contacts rated for 20 A at

120 and 277V AC. They are typically mechanically latched, requiring only a momentary

24V rectified AC switch circuit pulse to either open or close the load contacts. However, it

should be noted that an open or failed unlatch control circuit will fail to unlatch the relay. For

this reason, a mechanical latch unit should not be used where protection is needed against

automatic restart after a power failure or where reliability to a control function is critical to

safety.

There are also low-voltage industrial relays (containing no mechanical latch) available. These

1-…12-pole low-voltage industrial relays are available with contacts rated for 20…35 A for

tungsten lamp loads to 480V AC. These industrial relays are modular and generally contain

contacts that can easily be replaced or converted from normally open to normally closed (and

visa versa) in the field. See Figure 5.

A step-down transformer is required to provide low-voltage control power for relay actuation.

One transformer can typically supply power for up to 15 relays, provided properly sized wiring

and transformer is used. Low-voltage control wiring must be segregated from other lighting

circuit conductors. See Figure 5.

Figure 5. Allen-Bradley Bulletin 700-PK Relay, 700-PH Relay, and 1497 Control Transformer

Low-voltage relays are most often used in installations where a very high degree of selective

lighting control is desired as they can control individual lighting fixtures.

Bulletin 700-PK Bulletin 1497

Bulletin 700-PH

Bulletin 500 Lighting Contactors

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Application

Considerations

for UL 67 Listed

Panelboards

and UL 508

When applying a lighting contactor to a UL 67 listed panelboard, the mechanically held

type has certain advantages. The fact that the mechanically held version can be supplied

with a single pulse-operated coil assures greater contact pressure, essential for

withstanding short circuit fault currents. For example, a typical mechanically held, 20 A

lighting contactor can withstand an available 22,000 A fault current when used with a 30 A

molded case circuit breaker. Thus, they are satisfactory for use with UL 67 listed

panelboards.

In addition to withstand current rating, consideration should be given to the type of lighting

load. UL lists lighting contactors for general use loads, ballast (fluorescent) loads and

tungsten (incandescent) loads. UL 508 requirements for ballast loads are more stringent

than those for a general-use load, because UL requires ballast testing at a lower power

factor and twice the nominal current rating. The requirements for a tungsten load are more

stringent because they have to be tested for high inrush currents. A UL listed lighting

contactor suitable for all three classes of load will have its nameplate so marked. The

number of poles required for single-phase and three-phase applications also have a

bearing on the continuous duty rating. Typical ratings for a small AC lighting contactor are

shown in Tables 1 and 2.

The Allen-Bradley Bulletin 500LC mechanically held lighting contactor is suited for UL 67

listed panelboards; however, it should be noted that many motor starter contactors,

general-purpose relays, electrically operated circuit breakers, and some lighting contactors

are not suited for UL 67 listed panelboards. Furthermore, they are not usually rated as per

above nor listed per UL 508 requirements. Furthermore, use of a circuit breaker with trip

elements for repetitive switching can alter the breaker’s ability as an overcurrent protective

device. Manufacturers’ catalogs and technical literature should be consulted to ensure that

the equipment is properly rated for the application.

Table 1 Continuous Duty Rating

Load

Type

Amperes

Continuous

Pole to Load

1 for 1ø 2 for 1ø

3 for 3ø

Tungsten 20 250V AC 250V AC

Ballast 20 277VAC 480VAC

General 30 347V AC 600V AC

Table 2 Available Symmetrical

Amperes RMS

Service

Voltage

When Used with Molded

Case Circuit Breakers

Withstand

Current

Rating (Amps)

Max.

Breaker

Size (Amps)

250V AC 22,000

480V AC 14,000 30

600V AC 10,000

Bulletin 500 Lighting Contactors

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UL 508 requires:

Tungsten Loads

Endurance: 6,000 cycles of operation of tungsten filament lamps at rated current (20 A),

250V AC at a duty cycle of one second on, 59 seconds off. This duty cycle allows enough off

time for the tungsten filament to cool so that the next time that is energized, the switch must

close on approximately 20 times rated current for up to 14 cycles which is characteristic of

tungsten loads. This duty cycle assures the worst test conditions.

Overload: 50 cycles of operation at 1.5 times rated current (30 A), 0.75…0.80 power factor,

600V AC.

Ballast (electric discharge lamps)

Endurance: 6,000 cycles of operation at two times rated current (40 A), 0.4…0.5 power factor,

480V AC.

Overload: 50 cycles of operation at three times rated current (60 A), 0.4…0.5 power factor,

480V AC.

General Use

Endurance: 6,000 cycles of operation at rated current (20 A), 0.75…0.80 power factor, 600V AC.

Overload: 50 cycles of operation at 1.5 times rated current (30 A), 0.75…0.80 power factor,

600V AC.

Power Factor Corrected Ballast ➊

The Allen-Bradley Bulletin 500LC Lighting Contactor is suitable for power factor corrected

ballast far in excess of 6,000 cycles of operation.

➊ Important: UL does not test for this requirement. However, we believe that this additional

endurance test is a valuable, and unique, feature that illustrates the lighting contactors high

reliability.

Bulletin 500 Lighting Contactors

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Lighting Control

Methods and

Sensors

Control Modules

The versatility of controlling lighting contactors is illustrated by the availability of optimal

control accessories that can be provided to interface with various control schemes such as

energy management systems, microprocessors, photoelectric cells and timers. These

accessories may be in the form of discrete auxiliary relays or combined with solid-state

modules, with the trend towards the latter. Three control methods are two-wire control,

three-wire control, and start-stop control.

Figure 6 shows a typical wiring diagram of a 20 A multi-pole lighting contactor being

controlled from two (2) remotely located (three-position, momentary, center off) control

stations. The control stations in this figure are shown with signal lamps to indicate open or

closed status of the lighting contactors’ main contacts. Lighting contactors of this type

typically can control from two to twelve 20 A branch lighting circuits.

Figure 6. Typical Wiring Diagram

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Two-Wire Control

If the lighting contactor is being operated from a programmable source, logic controller, or any

control device providing control voltage to the lighting contactor by closing a set of single-pole

maintained contacts, it would be necessary to provide an intermediate control device or a twowire

control module. Solid-state control modules provide control voltage to the contactor by

responding to the opening and the closing single-pole single-throw (SPST) maintained output

contacts in the primary control device. Therefore, different control voltages can be applied to

operate the lighting contactor (i.e., 12V AC/DC, 24V AC/DC, 120V AC, 240V AC, 277 V AC).

When utilizing a mechanically held design (e.g., the Allen-Bradley 500LC Lighting Contactor),

such lighting contactors only require a momentary pulse of current to operate, the maintained

current from the primary control device is converted to a momentary on/off pulse to the coil.

Therefore, the coil only experiences a momentary pulse of current to open and close the lighting

contactor’s main contacts. See Figure 7.

Figure 7. Two-Wire Control

Bulletin 500 Lighting Contactors

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Three-Wire Control

The three-wire control method permits extended control line runs. It provides three-wire

control of the lighting contactor whereby one circuit is energized to close the lighting

contactor and another is energized to open the lighting contactor. If neither or both circuits

are energized, no operation will occur. Therefore, a single-pole, three-positioned

(maintained off-momentary on position) type control station as shown in Figure 7, or two

interlocked normally open push buttons, can be used with the accessory to operate the

contactor. See Figure 8.

Figure 8. Three-Wire Control

Start-Stop Control

This control method provides start-stop (on/off) control of the lighting contactor. The

accessory is energized to close the lighting contactor and de-energized to open the lighting

contactor. Therefore, one normally closed and one normally open control station can be

used with the accessory to operate the lighting contactor. See Figure 9.

Figure 9. Stop-Start Control

Bulletin 500 Lighting Contactors

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Optional control accessories can be applied at various control voltages such as 24V DC, 24V AC,

120V AC, and 277V AC. The solid-state versions are compact and can often be mounted directly

on the contactor. Their power consumption is extremely low (less than 1.0 VA), thereby making

them particularly suitable for energy management systems and long control wire runs. See

Figure 10.

Figure 10. Bulletin 500LC Mechanically Held Lighting Contactor with Form C Start-Stop

Control Module

Control Line Runs

Consideration should be given to control line runs when selecting lighting contactors and to the

size of control wire between the lighting contactor and control station. The longer the line run,

the larger the required wire size. Manufacturers provide line run data for lighting contactors

using various wire sizes. When more than one lighting contactor is connected to the same

control conductors, the data can be used in terms of “contactor feet.” The allowable run for a

group of lighting contactors is equal to the listed values divided by the number of lighting

contactors. For example, if one lighting contactor has an allowable run of 1000 feet with

#12 wire, 4 lighting contactors will be limited to 250 feet if they are operated simultaneously.

Auxiliary relays and solid-state modules, as previously discussed, are often used where long

control runs are required and it is desirable to limit the wire size.

Bulletin 500 Lighting Contactors