THE PROBLEM

Lighting fixtures are traditionally switched ON and OFF through the power circuit by a mechanical switch requiring the full current of the lighting load to be carried by the switch. If a mechanical switch is remote and distant from a lighting fixture, wiring between the fixture and switch also must accommodate full current of the lighting load. This leads to resistive voltage drops and an undesirable loss of power. The problem is further aggravated for low voltage lighting, since the power loss incurred from resistive voltage drops becomes a higher proportion of the power consumed by the lighting.

Power losses from resistive voltage drops are conventionally reduced by using electro-mechanical relay interfaces. Electro-mechanical relay power switching systems minimize high power losses, but increase the complexity and cost of lighting systems. Even with electro-mechanical relay interfaces, mechanical on/off switches do not integrate well with automated remote functions desirable for energy conservation, such as occupancy sensing and programmed control. Adding such automated remote functions to to electro-mechanical relay power switching systems further increases the complexity and cost by requiring extra hardware and costly electricians' time to alter "hard-wire" switching arrangements.

THE NEXTEK SOLUTION

Nextek lighting ballast include a built in all-electronic switching interface with optical isolation from the load power electronics in the ballast. The Nextek solution is a functional replacement for an electro-mechanical relay, but is more reliable, more efficient, and less expensive.

Mechanical switches or transistor-interfaces external to and remote from Nextek ballast switch the ballast on and off. No external power supply is required, the signal current of only 0.0025 ampere can be derived from the ballast without significant power loss (0.1 watt per ballast). Alternatively, an external low current signal source may be used to effect ON/OFF operation. Both methods are compliant with motion sensors, timer circuits and automated electronic control. As many as 32 Nextek ballast and corresponding fixtures can be switched with the same current required to energize one low voltage remote mechanical relay (24VDC/0.80 ampere).

The combination of low voltage/low current switching with optical isolation permits the use of telephone-type wiring and connectors. This is consistent with the requirements applied to cabling and saves money both by lowering the costs of parts and installation.

The following diagrams detail typical materials specifications and hook-up recommendations.

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