Torque gets the attention on a motor spec sheet. Tube diameter decides whether the motor goes in at all. The Somfy LT50 506S2 (1033401) needs a roller tube with a minimum inner diameter of 1.85 in, and it turns a 6 Nm shaft at 38 rpm on 120V house power. Installers reach for this one on exterior solar screens and on interior shades that run from a wall switch.
Start with the tube, then the torque
Somfy builds the 506S2 on the LT50 platform, so the motor body measures 1.97 in across and the external diameter sits at 1.77 in. The unwrapped length runs 20.2 in. Any tube with an inner diameter of 1.85 in or more accepts the motor once you add the matching crown and drive.
Torque sizing follows the fabric. A 6 Nm motor at 38 rpm suits lighter shade assemblies where the roll weight stays modest and the drop runs short to medium. Heavier exterior screens and wide awnings call for the 20 Nm and 30 Nm members of the same wired LT50 line. Buyers who need more lift move up inside the family and keep the same tube hardware.
The 38 rpm figure matters on tall openings. Faster rotation shortens travel time, so a screen on a two story glass wall finishes its run sooner than the same drop on a 14 rpm motor.
Shades this motor drives
Somfy publishes three applications for reference 1033401. Exterior solar screens top the list, and interior window coverings follow. Somfy also names retractable insect screens.
Each of those runs on a wired signal. The 506S2 carries no radio receiver, so a maintained switch, a relay, or a shade control panel drives it. Commercial jobs favor that path. A contractor pulling conduit during framing lands the motor cable at a switch box and hands the room over with no remote to pair and no battery to replace.
Verified specifications
| Specification | Value |
|---|---|
| Somfy reference | 1033401 (506S2 6/38 SJTW 10FT UNIT) |
| Torque | 6 Nm (53 in-lb) |
| Speed | 38 rpm |
| Power supply | 120V AC, 60 Hz (108 to 126 V) |
| Rated current | 0.7 A |
| Power consumption | 80 W in operation, 0 W standby |
| Sound level | 55 dB |
| Head type | Star |
| Limit switch | Mechanical, 46 limit turns, repeatability +/- 5 |
| Minimum tube inner diameter | 1.85 in |
| Motor diameter | 1.97 in (external diameter 1.77 in) |
| Unwrapped length | 20.2 in |
| Cable | SJTW, 4 conductor, white, 9.84 ft, stripped ends, detachable at the head |
| Ingress protection | IP 44, insulation class I |
| Operating temperature | -13 to 158 F (storage -4 to 176 F) |
| Thermal protection | 4 minutes continuous run |
| Applications | Exterior solar screens, interior shades, retractable insect screens |
| Approval and warranty | UR, 5 year Somfy warranty |
Two numbers on that table shape most purchases. The 1.85 in tube minimum sets the hardware list. The 4 minute thermal protection window sets expectations on long runs, since the motor pauses to cool after sustained operation and resumes once it drops back to temperature.
Tube fit and bracket choice
A crown centers the motor inside the tube and a drive transmits rotation to it. Pick the pair that matches your tube profile. The Somfy LT50 2.5 in Round Crown and Drive Set (9012231) handles round tube, and the Somfy Octagonal LT50 70mm Crown and Drive Set (9012234) handles 70mm octagonal tube on exterior shutter and screen work.
Head support comes next. This motor carries a STAR head, so the Somfy LT50 Star Head Motor Bracket (9410651) seats the head and locks it against rotation. The Somfy LT50 Universal Motor Bracket (9410665) gives you another mounting pattern where the pocket geometry rules out the star plate. Measure the pocket depth before you order. The motor adds 20.2 in to the tube assembly, and the bracket plus idler end take their own space.
Wiring and switch control
Somfy terminates this motor with a 9.84 ft SJTW cable in four conductors, stripped at the ends, and the cable detaches at the motor head. That detail saves a trip up the ladder. An electrician can run the cable to the switch box and leave it, and a shade installer can bring the motor up later and connect it at the head.
Four conductors cover the ground and the common plus both directional legs. A maintained rocker or a keyswitch sends power down one leg to raise and down the other to lower. Building automation shops land those legs on a relay card and the shade answers a dry contact command. Insulation class I means the ground conductor does real work, so bond it.
Power draw stays low at 0.7 A and 80 W, and the motor settles to 0 W in standby. A panel feeding a bank of these motors sizes off the simultaneous load rather than the count.
Limit setting and install notes
Mechanical limits run this motor. Two adjustment screws on the head set the upper and lower stop, and the mechanism holds 46 turns of travel. Set the limits with the fabric attached and the tube in the brackets, then cycle the shade twice to confirm the stop lands where you want it. Repeatability sits at +/- 5, which keeps the hem line steady across cycles.
Mount the head so the limit screws stay reachable. Pocket installs punish a motor turned screw side to the wall, and Somfy allows several motorhead orientations on this platform for that reason. The IP 44 rating covers splash exposure under a hood or inside a cassette. Keep the motor out of standing water and out of direct weather.
Sound measures 55 dB. Exterior screens and back of house openings absorb that. Bedrooms and conference rooms deserve a quieter Sonesse motor instead.
The Somfy 506S2 120V 4-Wire Motor (1033401) ships as a motor on its own. Add the crown and drive that match your tube, then the bracket that matches your pocket. A star head bracket and a round crown and drive set cover the most common roller screen build. Keep the Somfy reference number with the job file. Limit settings and replacement cables both start from that number.
Frequently asked questions
What tube size fits the Somfy 506S2 1033401?
Somfy publishes a minimum tube inner diameter of 1.85 in for this motor. The motor body measures 1.97 in across with an external diameter of 1.77 in. Match the crown and drive to your tube profile, round or 70mm octagonal, and the motor centers inside the tube once you seat the drive wheel.
How much weight will 6 Nm lift?
Lift capacity depends on tube diameter, fabric weight, roll build, and drop height, so Somfy rates the motor in torque rather than pounds. A 6 Nm motor suits lighter shade assemblies with short to medium drops. Larger exterior screens move up to the 20 Nm or 30 Nm motors in the same wired LT50 range.
Does this motor work with a Somfy remote?
The 506S2 at reference 1033401 carries no radio receiver, so it answers a wired control only. A maintained switch or a relay output drives it. Somfy offers RTS and Zigbee versions of the LT50 platform for remote and app control, and those motors carry their own reference numbers.
Can an installer replace the power cable?
Yes. Somfy publishes the cable as detachable at the motor head on this reference, and supplies it as a 9.84 ft SJTW cable in four conductors with stripped ends. An installer disconnects at the head, which allows a cable swap or a length change without pulling the motor out of the tube.
Shade Motors Direct is an authorized source for genuine Somfy motorized window shade, blind, and drapery parts.
