1225 Long-Run Neon: 12×25mm, 12W/m, Deep-Body Fixing

The body twists in the slot before it ever fails electrically. A 12 × 25 mm section is 25 mm deep and only 12 mm wide, so a clip that bears on one face holds it like a cantilever. Under thermal cycling the free side walks, the diffuser turns a few degrees off the wall, and the line that was straight at handover reads as a wave from the other side of the street.

A 12 × 25 mm profile is the deepest body in the Long Run range. It is built for large-scale outlines — bridge parapets, tower edges, long façade bands — where the body must hold a straight line over tens of metres and survive weather. The depth is a structural advantage only if the fixing engages the full section.

1. Where a deep, narrow body goes wrong

All four are fixing problems. The body is not too deep; the detail was designed for a shallower profile.

2. Optical: a 12 mm face with 25 mm of depth behind it

120 × SMD 2835 per metre at 8.33 mm pitch behind a 12 mm diffused face gives a continuous line from about 150 mm outward — the same optical behaviour as the 12 × 12 and 12 × 20 bodies.

What changes is the aperture. With 25 mm of depth, the emitting face sits further back from the opening. In a reveal:

• Flush or near-flush: the line reads normally, with a soft edge.
• Set back more than 15 mm: the side walls begin to cut the beam; the line narrows and the surface beside it falls into shadow.
• Seen at an angle: the deep body shows a visible side wall, which reads as a dark band beside the lit face.

That side wall is the reason this body belongs on a large-scale outline, not in a 15 mm interior reveal. At 30 m, the side wall is invisible. At 300 mm, it is the detail.

Colour range 1800 / 2700 / 3000 / 4000 / 6000 K, CRI >90.

3. The fixing detail that holds a 25 mm section

The clip must engage both side walls of the body, not one. Three rules:

1. Two-sided clips, sized to the 12 × 25 section. A 12 × 12 clip will close on the face and leave the depth unsupported.

2. Clip spacing 200 mm on straights, 150 mm on exposed elevations, plus a clip at every tangent. The cantilever length between clips is what allows the wave.

3. Continuous channel, not intermittent blocks. The channel takes the straight line; the clips hold the body in the channel.

Where the body runs vertically on a façade, add a retainer at the base and at every third clip. A 25 mm body carries more wind moment than a 12 mm body, and the clips see it as a peel load.

4. Electrical: 12 W/m, 24 V and 36 V

The electrical rules are the same as any 24 V long run: 5 m per feed as the default, 0.75 mm² conductor as the floor, driver at total wattage plus 20–25 % headroom. The 36 V option reduces current by one third and extends the practical interval; confirm the exact model before designing around it.

Cut at marked points: 50 mm, six LEDs.

Feed drop at the segment current (5 m out + 5 m back):

Use 0.75 mm² as the floor; step up to 1.00 mm² where the driver sits more than 5 m from the first tap.

5. Thermal: the best perimeter in the range

A 12 × 25 section has 74 mm of perimeter, the highest in the Long Run range at 12 W/m. Expect roughly 9–13 K rise above ambient in free air, lower against a metal channel.

The deep body is also the easiest to ventilate: there is room behind it for an air gap, and room at the ends for convection. Use that. A deep body packed into a sealed slot gives away its thermal advantage.

6. Bending and sealing a deep section

• Bend radius: the neutral axis of a 25 mm deep section sits further from the emitting face than a 12 mm body. The minimum radius is correspondingly larger. Do not template a 1225 corner from a 1212 detail.
• Bend plane: form in the designed plane on a jig; the depth makes a twist failure much more likely.
• Sealing: moulded cap sized for the section, potted joint, joint on a vertical face and at the high end of the run.
• Movement: leave an expansion allowance at both ends of a long channel run; do not pin the body at both ends.

7. Commissioning checks

8. Engineering FAQ

What is the difference between the 1220 and the 1225?

Both are 12 mm face, 12 W/m deep bodies. The 1225 is 25 mm deep against 20 mm, with more perimeter and a larger minimum bend radius. Choose the 1225 where the body must hold a straight line over a long span or carry more wind; choose the 1220 where the reveal is tighter.

Can I use a 12 × 12 clip on this body?

No. A clip sized for 12 × 12 closes on the face and leaves the 25 mm depth unsupported, which is exactly how a cantilever wave starts. Use a two-sided clip sized for the section.

Is a deep body suitable for a tight architectural reveal?

No. At 25 mm depth, the body needs an opening that lets the face sit near the surface. In a 15 mm reveal it reads as a recessed slot with a dark side wall. Use the 1212 or 1220 for tighter details.

9. Specification summary

Running a large-scale outline? Send the span, the exposure, and the reveal section. We will return a two-sided clip schedule and a bend radius that suits the depth.