1220 Long-Run Neon: 12×20mm, 12W/m, Façade Fixing Detail

At three metres the line looks right. At thirty metres, the same 12 × 20 mm body reads as a heavy band, and the client asks why the "neon" looks like a plastic tube. Nothing changed except the viewing distance: a 20 mm deep section has visible volume, and volume is what the eye reads before it reads brightness.

A 12 × 20 mm profile is the deep-body option in the Long Run range. It is chosen for façades and bridge lines where the body must be seen from a distance and must survive wind. Both of those requirements are structural, not optical, and both are decided by the fixing detail.

1. What the 20 mm depth actually buys

The output is identical at 12 W/m. The difference is presence and structure. If the design calls for a thin line, this is the wrong body; if it calls for a façade element that holds its shape across a long elevation, the extra depth is the reason to specify it.

2. Viewing distance: when a line becomes a band

The emitting face is 12 mm, but the body is 20 mm deep. At a distance, the eye integrates the whole section, not just the lit face.

• Up to 10 m: reads as a line of about 12–14 mm.
• 10–30 m: the depth becomes visible; the line reads as a 20 mm band with a lit face.
• Beyond 30 m: the body reads as a continuous architectural element, and the individual fixing points disappear.

This is useful on a bridge or a tower where a 12 mm body would vanish at distance. It is wrong on a shopfront where the detail is seen from 2 m and the client wants a fine line.

3. Wind load and the fixing schedule

A 20 mm deep body has more sail area than a 12 mm body. On an exposed façade, that load goes straight into the clips.

• Clip spacing: 200 mm on sheltered elevations, 150 mm on exposed façades and anywhere the body runs across the wind.
• Fix at both ends of every straight run, and at every tangent point on a curve.
• Do not rely on the channel alone. The channel locates the body; the clips carry the load. On a high-rise, add a mechanical retainer at every third clip.
• Allow for thermal movement. A long aluminium channel expands; if the body is pinned at both ends with no allowance, the silicone takes the movement as tension.

On a bridge or a tall façade, the body should be detailed with a continuous channel and a clip schedule that assumes gust loading, not just dead weight.

4. Optical and electrical

120 × SMD 2835 per metre at an 8.33 mm pitch behind a 12 mm face: continuous from about 150 mm outward, the most forgiving diffuser in the range. Colour range 1800 / 2700 / 3000 / 4000 / 6000 K, CRI >90.

Electrical is the standard 12 W/m:

For a façade run of 20 m or more, the 36 V option reduces current and extends the feed interval. Use 5 m feeds on 24 V; confirm the 36 V model and driver before committing to a longer interval.

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 heat path in the range

A 12 × 20 section has 64 mm of perimeter — the highest in the Long Run range at 12 W/m. Expect roughly 10–14 K rise above ambient in free air, lower again against a metal channel.

That does not mean the body can be buried. It means a 12 W/m 1220 in a ventilated façade cavity will run cooler than a 1212 in the same cavity. The channel and the cavity ventilation still do the work.

6. Installation sequence for a façade

1. Set out the channel runs and confirm the substrate fixing pattern before any body is cut.

2. Fix the channel continuously, not at intervals; the channel is the thermal and mechanical datum.

3. Clip at 150–200 mm, with a clip at every end and tangent.

4. Cut at marked points, seal every outdoor end with a moulded cap and potted joint, and keep joints off horizontal surfaces.

5. Commission at night, from the design viewing distance, not from the access platform.

7. Commissioning checks

8. Engineering FAQ

Is a 20 mm body brighter than a 12 mm body at the same wattage?

No. Same 12 W/m, same 12 mm face, same flux. It looks more present at distance because of its volume, not because it emits more.

How do I fix a 1220 run on an exposed high-rise façade?

Use a continuous aluminium channel, clips at 150 mm, a mechanical retainer every third clip, and an allowance for thermal movement at the ends. Confirm the wind load with the façade engineer; the clip schedule should be designed, not copied from an interior detail.

Can I use 36 V on a 25 m façade run?

Yes, if the 36 V model is specified and the driver matches. The lower current reduces feed drop and can remove one or two taps. Do not mix 24 V and 36 V on one circuit.

9. Specification summary

Specifying a façade line? Send the elevation, the viewing distance, and the wind zone. We will return a channel and clip schedule sized for the load, not just for the look.