1 

Overview of NIOSH LED Cap Lamps

The NIOSH Office of Mine Safety and Health Research (OMSHR) 

is conducting mine illumination research to address the visual needs

of the aging miner workforce and to improve miner safety by

reducing glare and improving a miner’s ability to see mine hazards 

associated with slip/trip/fall accidents and moving machinery 

accidents. This research enables improvements in mine lighting so 

that miners can better see hazards; thus, the research will enable a 

reduction of accidents. The result of this research is an MSHAapproved, light-emitting diode (LED) cap lamp model called the 

GEN 4. Also developed were similar models—the GEN 5, the GEN

4E, and the GEN 5E—with other features as described below.

The company LED Specialists designed and built the printed circuit board (PCB) for all models of the 

cap lamp according to NIOSH specifications. This company also programmed the PCBs for models 

GEN4 and GEN 5. OMSHR researchers modified this software for the models GEN 4E and GEN 5E. 

NIOSH also created a documentation package for each model of cap lamp. The files created by NIOSH 

and by LED Specialists are in their respective folders of the documentation package, available for 

download from the NIOSH Mining website at www.cdc.gov/niosh/mining. 

NIOSH-developed LED cap 

lamp GEN 4 model.

GEN 4 Model

NIOSH developed the GEN 4 for use in underground coal mines. The GEN 4 uses the battery, battery 

cable, and headpiece of an existing MSHA-approved cap lamp that is commercially available. 

Researchers retrofitted this existing cap lamp with new optics, three LEDs, an LED mounting plate, a 

printed circuit board (PCB) that provides programmable functional control of the cap lamp, and a single

integrated circuit (IC) driver with three constant current sources for the LEDs. NIOSH research was the 

basis for the retrofit of all components and associated software. The GEN 4 model is MSHA-approved 

for use in underground mines. 

GEN 5 Model

A second LED cap lamp, model GEN 5, was developed by NIOSH to better suit the visual tasks 

performed in underground metal/nonmetal mines. The primary difference from the GEN 4 is that a more 

intense spot beam is available for illuminating objects or mine areas that are 40 feet or greater from the 

cap lamp. NIOSH achieved this with a change in the LED and optic used for the spot beam as well as 

modifying the PCB to have dual IC drivers that enable the spot beam to operate at a greater range of 

current. The GEN 5 model is not MSHA-approved for use in underground mines. 

GEN 4E and GEN 5E Models

The next cap lamps NIOSH developed—models GEN 4E and GEN 5E—were reduced-power versions 

of the GEN 4 and GEN 5 with both hardware and software changes. These reduced-power models can 

operate using a single lithium-ion battery cell. Both the GEN4E and GEN 5E can provide at least 11 

hours of operation at the highest cap lamp intensity. The GEN 4E and GEN 5 models are not MSHAapproved for use in underground mines. 
2 

GEN 4 Cap Lamp Overview

Intended for Coal Mining

1.1. Temperature range: 

1.1.1. Operational ambient temperature is 0° C to 40° C. 

1.2. Functional requirements: 

1.2.1. The GEN 4 cap lamp uses three LEDs. The LED drive currents, in milliamps (ma),

depend on the external switch and battery condition as listed by Table 1. 

Table 1 - The GEN 4 cap lamp functions

Condition Comments

Off --

1st switch press Initial 2-3 sec. self-test then normal mode low

intensity

2nd switch press normal mode medium intensity

3rd switch press normal mode high intensity

4th switch press off mode

Low battery low battery on when battery = 3.5 Vdc

Low battery 1st switch press low battery off

Low battery 2nd switch press low battery on

1.3. Battery pack: 

1.3.1. The cap lamp is powered by a 8-cell lithium-ion battery 

1.3.2. Vout battery for normal operation: 3.5 Vdc to 4.2 Vdc

1.3.3. Vout for low battery conditions: 3.5 Vdc

1.3.4. Capacity: 17.6 amp hours 

1.3.5. The battery pack contains a shutdown circuit that prevents the battery from discharging 

below 3.0 Vdc. 

1.4. Operating power for normal mode high intensity at 25° C ambient at 4.0 Vdc: 

1.4.1. normal mode low intensity; 84 ma; 0.336 watts 

1.4.2. normal mode medium intensity; 248 ma; 0.992 watts 

1.4.3. spot mode high intensity; 374 ma; 1.50 watts 

1.5. Circuit board (single driver) PCB0120-01 Rev PR2 

1.6. Maximum LED currents (ma): LED1 = 120; LED2 = 160; LED3 = 80 

NOTE: File NCL-T-001-rev 5.xls lists the primary files for GEN4
3 

GEN 5 Cap Lamp Overview

Intended for Metal/Nonmetal Mining

1.1. Temperature range: 

1.1.1. Operational ambient temperature is 0° C to 40° C. 

1.2. Functional requirements: 

1.2.1. The GEN 5 cap lamp uses three LEDs. The LED drive currents, in milliamps (ma), 

depend on the external switch and battery condition as listed in Table 2. 

Table 2 - The GEN 5 cap lamp functions

Condition Comments

Off --

1st switch press Initial 2-3 sec. self-test then normal mode low

intensity

2nd switch press normal mode high intensity

3rd switch press spot mode high intensity

4th switch press off mode

Low battery low battery on when battery = 3.5 Vdc

Low battery 1st switch press low battery off

Low battery 2nd switch press low battery on

1.3. Battery pack: 

1.3.1. The cap lamp is powered by a 8-cell lithium-ion battery 

1.3.2. Vout battery for normal operation: 3.5 Vdc to 4.2 Vdc

1.3.3. Vout for low battery conditions: 3.5 Vdc

1.3.4. Capacity: 17.6 amp hours 

1.3.5. The battery pack contains a shutdown circuit that prevents the battery from discharging 

below 3.0 Vdc. 

1.4. Operating power for normal mode high intensity at 25° C ambient and 4.0 Vdc: 

1.4.1. normal mode low intensity; 64 ma; 0.256 watts 

1.4.2. normal mode high intensity; 373 ma; 1.49 watts

1.4.3. spot mode high intensity; 375 ma; 1.50 watts 

1.5. Circuit board (dual driver) PCB 0137-01 REV A 

1.6. Maximum LED currents (ma): LED1 = 360; LED2 = 240; LED3 = 120 

NOTE: File NCL5-T-001-rev 1.xls lists the primary files for GEN 5
4 

GEN 4E Cap Lamp Overview

Intended for Coal or Metal/Nonmetal Mining

1.1. Temperature range: 

1.1.1. Operational ambient temperature is 0° C. to 40° C. 

1.2. Functional requirements: 

1.2.1. The GEN 4E cap lamp uses three LEDs. The LED drive currents, in milliamps (ma), 

depend on the external switch and battery condition as listed by Table 3. 

Table 3 - The GEN 4E cap lamp functions

Condition Comments

Off --

1st switch press Initial 2-3 sec. self-test then normal mode low

intensity

2nd switch press normal mode high intensity

3rd switch press spot mode high intensity

4th switch press off mode

Low battery low battery on when battery = 2.95 Vdc

Low battery 1st switch press low battery off

Low battery 2nd switch press low battery on

1.3. Battery: 

1.3.1. The cap lamp is powered by a K2 #26650EV lithium cell 

1.3.2. Vout battery for normal operation: 3.2 Vdc

1.3.3. Vout for low battery conditions: 2.95 Vdc

1.3.4. Capacity: 3.2 amp hours. 

1.4. Operating power 25° C ambient and Vin = 3.2 Vdc: 

1.4.1. normal mode low intensity; 62 ma; 0.198 watts

1.4.2. normal mode high intensity; 282 ma; 0.902 watts

1.4.3. spot mode high intensity; 183 ma; 0.586 watts 

1.5. Circuit board (dual driver) PCB 0137-01 REV A 

1.6. Maximum LED currents (ma): LED1 = 360; LED2 = 240; LED3 = 120 

NOTE: File NCL4E-T-001-rev0.xls lists the primary files for GEN4E
5 

GEN 5E Cap Lamp Overview

Intended for Coal or Metal/Nonmetal Mining

1.1. Temperature range: 

1.1.1. Operational ambient temperature is 0° C. to 40° C. 

1.2. Functional requirements: 

1.2.1. The GEN 5E cap lamp uses three LEDs. The drive currents in milliamps (ma) depend on 

the external switch and battery condition as listed by Table 4. 

Table 4 - The GEN 4E cap lamp functions

Condition Comments

Off --

1st switch press Initial 2-3 sec. self-test then low mode low intensity

2nd switch press high mode intensity

3rd switch press spot only mode high intensity

4th switch press off mode

Low battery low battery on when battery = 2.95 Vdc

Low battery 1st switch press low battery off

Low battery 2nd switch press low battery on

1.3. Battery: 

1.6.1. The cap lamp is powered by a K2 #26650EV lithium-ion cell

1.3.1. Vout battery for normal operation: 3.2 Vdc to 3.3 Vdc 

1.3.2. Vout for low battery conditions: 2.95 Vdc 

1.3.3. Capacity: 3.2 amp hours 

1.4. Operating power at 25° C ambient at Vin = 3.2 Vdc: 

1.4.1. normal mode low intensity; 62 ma; 0.198 watts 

1.4.2. normal mode high intensity; 282 ma; 0.902 watts 

1.4.3. spot mode high intensity; 183 ma; 0.586 watts 

1.5. Circuit board (dual driver) PCB 0137-01 REV A 

1.6. Maximum LED currents (ma): LED1 = 360; LED2 = 240; LED3 = 120 

NOTE: File NCL5E-T-001-rev 1.xls lists the primary files for GEN5E