Jeffrey Cheney

Interest

Lighting controls

A study interest. Not a claim that Jeffrey has commissioned a controls system.

Commercial lighting is rarely a switch and a row of fixtures anymore. Energy codes want the lights off, or at least down, when the room is empty or full of daylight. The electrician installs the line-voltage wiring, the low-voltage control wiring, and often stands there while someone proves the sequence.

Sensors

  • Occupancy sensors can turn lights on and off automatically. Ultrasonic, passive infrared, or dual technology. Mounting and aiming decide whether the sensor sees the room or a hallway walking past the door.
  • Vacancy sensors require a person to turn the lights on. They still turn them off after the room empties. Manual-on is what many energy-code spaces want, so a room does not light up because someone walked by.

Daylight harvesting

A photosensor watches the daylight and tells the fixtures near the glass to dim. The daylit zone has to be controlled separately from the interior, or the whole room dims when only the perimeter needed it. Placement matters: a sensor that looks at a fixture, instead of the task, will chase its own tail.

0–10V and DALI

0–10V is the common analog dimming method on commercial LED drivers. In the usual U.S. wiring, a violet and a gray (or pink) pair carry the signal. Ten volts is full output. Lower voltage dims. The pair is polarity-sensitive. Many drivers still need a line-voltage relay or a switched leg to turn fully off, because a 0–10V signal alone may not open the power to the driver. Class 2 dimming conductors are kept out of the same conduit as line voltage unless the cable and the code section allow it.

DALI (IEC 62386) is a digital bus. Each driver can have an address. Zones are often made in software instead of by pulling a new pair. A classic DALI subnet addresses up to 64 short addresses. The bus is two wires and, unlike 0–10V, polarity is not the thing that makes it work. Drivers, sensors, and the controller still have to speak the same version of the standard. DALI-2 is the certification program for that interoperability.

0-10V lighting control sketch A sensor and a relay panel feed a line-voltage relay and a separate 0-10 volt pair to a fixture. Sensor Relay panel Fixture line 0–10V
Line voltage switches the driver. The 0–10V pair tells it how bright to be.

Relay panels and networked systems

A relay panel puts many line-voltage relays in one can. A low-voltage switch, a time clock, or a network closet tells the relays what to do. Networked systems — product families such as Acuity nLight or Lutron’s room and whole-building systems, among others — add addresses, schedules, and software zoning. The brand is the spec’s choice. The field work is still homeruns, power supplies for the controllers, separation of Class 2 wiring, and a sequence that matches the drawing.

Energy code

ASHRAE/IES 90.1 and the International Energy Conservation Code are the two documents most U.S. cities point at. They are not the NEC. A city adopts a specific year, sometimes with amendments. California uses Title 24 instead. The Lighting Controls Academy’s write-up of the 2024 IECC says daylight-responsive controls are required for primary sidelit and toplit zones over 75 watts of general lighting, and when primary plus secondary sidelit zones together exceed 150 watts, with dimming to 15 percent or less and the ability to turn off. Small enclosed offices can be excepted. Those thresholds are why the article is linked below. The adopted book on the job is the one that counts.

Commissioning

Functional testing is part of the energy code, not a courtesy. Someone aims the sensor, sets the timeout, checks that daylight dimming does not fight the occupancy sensor, and writes down the result. A system that was never programmed is a code failure even if every wire rang out.

What's happening now

The current argument in this part of the trade is the 2024 energy code, which asks for daylight control at lower wattages than the previous IECC.

  • 2024 IECC and Lighting Controls Lighting Controls Academy

    Summarizes the 2024 IECC daylight-zone wattage thresholds, dimming to 15 percent, and the small-office exception.

  • 2024 IECC line card Leviton

    A manufacturer’s checklist of the same 2024 IECC lighting-control sections, useful as a second reading of the wattage triggers.

Code section numbers, energy-code rules, and utility practices change by edition and by city. The authority having jurisdiction, and the employer’s written program, decide what applies on a given job.