DASMA TDS 364 - Photoelectric Sensor Placement Height for Residential Garage Doors

Most garage door problems blamed on "sensors" are actually sensor height or alignment problems. DASMA TDS 364 establishes the correct installation height for photoelectric sensors and explains why that specific height is required by UL 325.

What this data sheet says

DASMA TDS 364 specifies that photoelectric sensor pairs on residential garage door operators must be mounted with the beam no more than 6 inches above the finished floor, with 4 to 6 inches being the standard recommended range. This requirement comes from UL 325, the safety standard for door operators, and is also reflected in 16 CFR § 1211.11, the federal consumer product safety regulation.

"Photoelectric sensors shall be installed so that the beam is no more than 6 inches above the floor surface to ensure detection of a small child."

The height limit is a safety calculation. A beam set at 6 inches or lower will detect a small child who has crawled or fallen into the door opening before the descending door makes contact. A beam set higher than 6 inches creates a gap between the floor and the beam where a very small child could be struck by the closing door without triggering the sensor.

TDS 364 also notes:

• Sensors must be installed on both sides of the door opening, with one unit transmitting and the other receiving.
• The sensor brackets must be attached securely to the door jamb, track, or a rigid mounting bracket so that alignment is maintained during door operation.
• Sensors should be positioned so that the beam path does not intersect the door panel track, which would cause constant beam interruption.

When it applies

The 6-inch maximum height applies to all residential garage door operators covered by UL 325. This includes operators installed in single-family homes, townhomes, condominiums with attached garages, and any other residential dwelling unit with an automatic garage door.

Improperly placed sensors are a common finding when a technician troubleshoots a door that refuses to close or reverses unexpectedly. In some cases, sensors were mounted too high (sometimes above 12 inches) because the installer placed them at a convenient bracket height rather than measuring from the floor. A door with sensors at the wrong height is not compliant with UL 325 and 16 CFR § 1211.11.

On the Front Range, sensor adjustment is also a common seasonal issue. Frost heave in concrete garage floors can slightly raise the floor surface near the sensor brackets after winter, effectively lowering the beam height relative to the floor and causing intermittent false triggers.

What this means for you

Measure your sensor height. Find the center of the sending and receiving sensor lenses and measure straight down to the floor. The beam should be 4 to 6 inches above the floor. If it is above 6 inches, the sensors need to be repositioned.

After any concrete work or floor leveling near the garage, re-check sensor height. Any change to the floor surface near the sensors affects the effective beam height.

Test the beam interruption response after any sensor adjustment. Once sensors are repositioned, run the door down and interrupt the beam with a 2-by-4 laid flat on the floor. The door should stop and reverse immediately.

G Brothers checks sensor height and alignment as part of every service call and during any opener installation across the Denver metro area and Front Range.

Full text and source

Download DASMA TDS 364 from the official TDS index at https://www.dasma.com/technical-data-sheets/.

This entry covers photoelectric sensor placement height for residential garage door operators under UL 325. Commercial door operators and gate operators have separate sensor placement requirements and are not covered by TDS 364.