# Switchroom normal-lighting control branch

Canonical URL: https://eloragrid.ai/symbols/switchroom-normal-lighting-control-branch
Publisher: Elora Grid
Updated: 2026-11-03
Lookup label: SNCB
Drawing use: Schematic
Reference families: Manufacturer

Representation: Functional block
Installation focus: switchrooms
Input: Local lighting command
Output: Normal lighting switched supply

Identifies the control path switching the assigned normal room-lighting circuit.

## In plain English

### What this block does

Identifies the control path switching the assigned normal room-lighting circuit.

### A simple example

In a switchroom, a normal lighting branch may be switched locally while the specified emergency luminaires remain connected to their own backed-up or integral supply. For this reference, the drawing identifies “Local lighting command” at the input and “Normal lighting switched supply” at the output. Emergency lighting can have a separate unswitched supply.

### What the drawings help you do

Start at the named input: Local lighting command. Identify its source device or document and the state represented on the drawing. Follow the named output: Normal lighting switched supply. Cross-reference its destination and separate the command from confirmation that the equipment responded.

### Terms

- Input: Local lighting command
- Output: Normal lighting switched supply
- Application reference: An explanation of a named drawing function or circuit relationship; the project documents define the equipment and its connections.

Concept diagram: Local lighting command → SNCB → Normal lighting switched supply
A reading guide. The entry's original illustration and input/output facts describe this application.

- [Indoor substation: lighting, fire and auxiliary services](https://www.electrical-installation.org/enwiki/Indoor_substation)


## What it represents

Identifies the control path switching the assigned normal room-lighting circuit. Lighting and access interfaces coordinate the electrical-room service circuits and their supervision. Normal lighting, emergency illumination and access indication have different power sources and purposes.
In a switchroom, a normal lighting branch may be switched locally while the specified emergency luminaires remain connected to their own backed-up or integral supply. For this reference, the drawing identifies “Local lighting command” at the input and “Normal lighting switched supply” at the output. Emergency lighting can have a separate unswitched supply.
Identify the lighting supply type, controlled circuit and the meaning of any test or failure output. A drawing symbol does not establish illumination levels, emergency duration or an approved egress arrangement. The functional block is an independent explanation of this named application. Equipment-specific ratings, terminal connections and operating conditions must be established in the project documentation.

## How to read it

- Start at the named input: Local lighting command. Identify its source device or document and the state represented on the drawing.
- Follow the named output: Normal lighting switched supply. Cross-reference its destination and separate the command from confirmation that the equipment responded.
- Emergency lighting can have a separate unswitched supply.
- Identify the lighting supply type, controlled circuit and the meaning of any test or failure output. A drawing symbol does not establish illumination levels, emergency duration or an approved egress arrangement.

## Information to show or reference

- Label the source and connection reference for local lighting command.
- Identify the destination and defined state of normal lighting switched supply.
- Record the equipment or control-document revision supporting this functional block.
- Check this application limit in the project design: Emergency lighting can have a separate unswitched supply.

## Important distinction

Emergency lighting can have a separate unswitched supply. This reference describes the named application; it does not establish a new IEC graphical symbol, an ANSI device-function number or an exact manufacturer connection diagram.

## Facts

- Representation: Functional block
- Installation focus: Switchrooms
- Input / boundary: Local lighting command
- Output / connection: Normal lighting switched supply
- Lookup label: SNCB is a library lookup label, not a standard device designation.

## Public references

- [Indoor substation: lighting, fire and auxiliary services](https://www.electrical-installation.org/enwiki/Indoor_substation) — Schneider Electric. Public technical context for switchroom lighting and access interfaces. Lighting, emergency lighting, fire provisions and substation auxiliary services. Original cause-and-effect examples require project design. The application text and educational graphic are independently authored; the publisher does not certify this representation.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.