Emergency Lighting: A Comprehensive Guide to BAES, BAEH, Sizing, and Requirements

Lucas Moreau Electrical Engineer · Low-voltage installation specialist · 15 years of experience

In brief

Emergency lighting is mandatory in public establishments (ERP) hosting 50 people or more, and in professional premises exceeding 300 m² on upper floors (or 100 m² on the ground floor/basement). It consists of two functions: evacuation signage (marking exits and escape routes) and anti-panic ambient lighting (5 lumens/m² minimum). The choice is between self-contained emergency lighting units (BAES) — simple to install, with an individual battery and SATI function — or a central power source suited to large installations. Eaton BAES units (UltraLED and UNILED ranges) are the references at Optim-Elec.

Why is emergency lighting essential?

Emergency lighting is designed to ensure a fast and safe evacuation in the event of a normal power supply failure. It switches on automatically and guides occupants toward emergency exits in complete darkness.

Establishments open to the public (ERP) and professional premises are subject to strict regulatory obligations set out by the French Building and Housing Code, fire safety regulations, and the NF C 71-800 (installation rules) and NF C 71-820 (maintenance) standards.

Key takeaway Emergency lighting is not just backup lighting. It fulfills a precise regulatory mission: enabling the evacuation of people and facilitating emergency response operations. Its absence or malfunction makes the operator criminally liable.

The two functions of emergency lighting

Evacuation signage vs. ambient lighting
Criteria	Evacuation signage	Ambient lighting (anti-panic)
Objective	Mark exits and guide people toward them	Maintain minimal lighting to prevent panic
Requirement	From 50 people accommodated	From 100 people on upper floors or 50 on ground floor/basement
Luminous flux	45 lumens minimum per unit	5 lumens/m² minimum
Spacing	At every change of direction + exits	Maximum 4 × the installation height
Minimum number	1 unit per exit + change of direction	Minimum 2 units per room or hall
Autonomy	1 hour minimum	1 hour minimum
Pictogram	Green signage pictogram (running man)	No specific pictogram

When is emergency lighting mandatory?

1Establishments open to the public (ERP)

All ERPs, regardless of category, must be equipped with emergency lighting. Evacuation signage is mandatory as soon as the capacity reaches 50 people. Ambient lighting is added from 100 people on upper floors or 50 people on the ground floor or basement.

2Professional premises (French Labor Code)

Workplaces require emergency lighting as soon as the floor area exceeds 300 m² on upper floors or 100 m² on the ground floor and basement. This requirement applies regardless of the number of occupants.

3Collective residential buildings

The common areas of collective residential buildings must be equipped with BAEH (Self-Contained Residential Lighting Units). These are specific units, different from BAES, with a 5-hour autonomy and a minimum luminous flux of 8 lumens.

BAES or central source: how to choose?

BAES vs. central source comparison
Criteria	BAES (Self-Contained Unit)	Central source
Principle	Each unit has its own battery	A single central battery powers all the light fixtures
Installation	Simple — one unit = one light point	Complex — specific secured wiring (CR1)
Maintenance	Built-in SATI function (automatic self-test)	Centralized maintenance at the control panel
Initial cost	Low to moderate	High (control panel + secured wiring)
Suited for	Small and medium installations, common ERPs	Large installations, hospitals, shopping centers
Replacement	Unit by unit, with no impact on the rest	Central battery to be replaced periodically

Key takeaway For the vast majority of installations (ERP categories 2 to 5, professional premises), BAES units are the simplest and most economical solution. A central source is mainly justified in very large-capacity establishments or when the architecture requires discreet recessed light fixtures.

BAES vs. BAEH: what's the difference?

BAES (Self-Contained Emergency Lighting Unit): intended for ERPs and professional premises. Provides evacuation signage (45 lumens, 1-hour autonomy) and/or ambient lighting. Equipped with the SATI function (Integrated Automatic Test System).
BAEH (Self-Contained Residential Lighting Unit): intended for the common areas of collective residential buildings. Minimum flux of 8 lumens, 5-hour autonomy. No evacuation pictogram.

The two types are not interchangeable: a BAEH cannot replace a BAES in an ERP, and vice versa.

How to size your installation?

Evacuation signage

Place an evacuation unit:

Above each emergency exit and exit door.
At every change of direction in circulation areas.
At every change of level (stairs, landings).
At every corridor intersection.
At obstacles and dead ends.

The unit must be visible from every point along the evacuation route. The maximum distance between two signage units must not exceed 15 meters.

Ambient lighting

The minimum intensity is 5 lumens/m² of floor area. The maximum spacing between units is 4 times the installation height (e.g., 3 m height → 12 m max spacing). Each room or hall must have at least 2 units to avoid complete darkness if one unit fails.

The SATI function: automatic self-test

The SATI function (Integrated Automatic Test System) has been mandatory on BAES units since 2014. It automates verification operations:

Automatic lamp test every 2 weeks (checking that the LED lights up).
Automatic battery test (autonomy) every 6 months (simulating a mains power failure).
Fault signaling via a visible LED indicator (green = OK, red = fault).
Test report viewable via the BAES remote control (Eaton TLU2 or TL 500).

The SATI function considerably reduces the maintenance workload while guaranteeing the installation's ongoing compliance.

Discover our emergency lighting units

→ All BAES and BAEH units → Eaton BAES units and remote controls

Frequently Asked Questions — Emergency Lighting

How does a BAES work?

A BAES (Self-Contained Emergency Lighting Unit) is equipped with a built-in battery that allows it to switch on automatically in the event of a normal power supply failure. It lights emergency exits and evacuation routes for a minimum of 1 hour with a flux of 45 lumens. The built-in SATI function performs automatic self-tests of the lamp (every 2 weeks) and the battery (every 6 months).

When is BAES installation mandatory?

BAES units are mandatory in ERPs as soon as the capacity reaches 50 people (evacuation signage) or 100 people on upper floors / 50 on the ground floor-basement (ambient lighting). In professional premises, the requirement applies as soon as the floor area exceeds 300 m² on upper floors or 100 m² on the ground floor and basement, regardless of the number of occupants.

What is the difference between a BAES and a BAEH?

The BAES is intended for ERPs and professional premises for evacuation signage (45 lumens, 1-hour autonomy, green pictogram). The BAEH is designed for the common areas of collective residential buildings (8 lumens minimum, 5-hour autonomy, no pictogram). The two are not interchangeable.

BAES or central source: which to choose?

BAES units are the simplest and most economical solution for most installations (ERP categories 2 to 5, professional premises). Each unit has its own battery and the SATI function automates maintenance. A central source is justified in very large installations (hospitals, shopping centers) where centralized management and discreet recessed light fixtures are needed.

What is the SATI function on a BAES?

The SATI function (Integrated Automatic Test System) has been mandatory since 2014 on all BAES units. It automates the lamp test every 2 weeks and the battery test every 6 months. An LED indicator signals faults (green = OK, red = fault). Results can be viewed via the BAES remote control.

How do you size the number of emergency lighting units?

For evacuation signage: one unit at each exit, change of direction, change of level, and intersection, with a maximum spacing of 15 m. For ambient lighting: 5 lumens/m² minimum, maximum spacing of 4 times the installation height, and at least 2 units per room or hall.

Which BAES brands are available at Optim-Elec?

Optim-Elec distributes Eaton BAES units, the benchmark brand in the French emergency lighting market. The range includes UltraLED units (45 lumens, SATI, 1 hour), UNILED units (high-performing entry-level range), as well as TLU2 remote controls (visibility+ and anti-panic function) and TL 500 (management of up to 500 units).

Need help sizing your emergency lighting?

Our technical team can help you choose and size your BAES and BAEH units.

Contact our technical team

By phone: 01 43 44 60 00 · By email: [email protected]

Key points to remember

Emergency lighting includes two functions: evacuation signage (from 50 people) and ambient lighting (from 100 people on upper floors).
BAES units are the standard solution: individual battery, built-in SATI, 45 lumens, 1-hour autonomy.
BAEH units are reserved for collective residential buildings (8 lumens, 5-hour autonomy).
A central source is only justified for very large installations.
The SATI function (mandatory since 2014) automates lamp and battery tests.
Sizing: 15 m max between signage units, 5 lm/m² for ambient lighting, minimum 2 units per room.
Optim-Elec distributes Eaton BAES units (UltraLED, UNILED) and TLU2 / TL 500 remote controls.