TOPIC:

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Code Requirements (NFPA 101)

7.9.2.3

I. CODE

The Emergency Lighting System Shall Be Arranged To Provide the Requited Illumination Automatically In the Event Of Any Interruption Of Normal Lighting Due To Any Of the Following:

- Failure Of a Public Utility Or Other Outside Electrical Power Supply

- Opening Of a Circuit Breaker Or Fuse

- Manual Act(s), Including Accidental Opening Of a Switch Controlling

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Normal Lighting Facilities

Code Interpretation

Considerations

I. CODE

Emergency Systems Must Respond To LOCAL Failures

- This Electrical Circuit Breaker

- More Nuanced Than Just Utility Power

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This Also Included Some Requirements About Local Fire Alarm Interfaces

This Has Ramifications On Architecture For Emergency Lighting Control Devices

The Architecture That Works...

II. CONTROL TOPOLOGIES

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Breaker Panel

Inverter

Lighting Control

ELCD

ELCD

Lighting Control

Non-Critical

Critical

Non-Critical

Critical

Why It Works

Capable Of Dealing With Localized Events:

- Local Circuit Breaker

- Local Fire Alarm

- Local Emergency

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Now Let's Explore Some Problematic Architectures...

II. CONTROL TOPOLOGIES

DALI/EcoSystem

Typically Implemented

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Loss Of Digital Bus Forces Light To Emergency Levels

II. CONTROL TOPOLOGIES

Non-Critical

Critical

Non-Critical

Critical

Notes:

Breaker Panel

Inverter

DALI/EcoSystem Controller

ELCD

Centralized Relay/0-10V Control With Phase Loss

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II. CONTROL TOPOLOGIES

Breaker Panel

Inverter

Phase Loss Sensor

Lighting Control Panel (Feed Through)

Non-Critical

Critical

Non-Critical

Critical

Override Signal

DALI/EcoSystem/Centralized Systems

The Problem

The Fixtures Will ONLY Ever Go Into Emergency Mode When There Is a Utility Failure

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The Fixtures Will Be Ignorant Of a Localized Emergency, Local Circuit Breaker Trips

The Solution Is To Have One UL 924 ELCD On Each Branch Circuit Breaker, Not Just the One Feeding the Controller

II. CONTROL TOPOLOGIES

Power Packs With UL 924 Functionality

Particularly Ones That Do Not Have a Dedicated Utility Sense Line

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Most Manufacturers Have Some Version Which Looks For a Power Outage Then Ignores Commands For 90 Minutes

These Devices Require a Loss In Power, Which Can Be Problematic For Very Fast Inverter Transfers

- Or Until They Hear a Known-To-Be-On-Utility Device

II. CONTROL TOPOLOGIES

What the Power Pack "Sees"

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Notes:

This Transfer To Emergency Power Is So Fast, the Device Can Not Really Notice That It's Happened

II. CONTROL TOPOLOGIES

The Solution Is To Use "Delayed Transfer" Options On Inverters

<2ms

What the Power Pack "Sees" Now

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Notes:

This Period Of Downtime Is Enough For the Lighting Controls To See the Power Loss Changeover

II. CONTROL TOPOLOGIES

>50ms

Notes On Phase Control & ELCDs

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II. CONTROL TOPOLOGIES

UL 1008

Lighting Control

FIRE ALARM INTERFACE

UTILITY POWER

EM POWER

SENSE

Non-Critical Loads

Critical Loads

Notes On Phase Control & ELCDs

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II. CONTROL TOPOLOGIES

UL 1008 ELCDs Are Expensive

Depending On the Breakdown You Might Be Able To Get Away With Having Everything On the Emergency System

- If It's Less Than ~75W Of Non-Critical Load, It's Probably Less Expensive To Back It All Up

Critical Loads

Critical Loads

Lighting Control

UL 924

SENSE

EM POWER

SWITCHED INPUT