Advertising flood light: aim from the base, level the face
A sign face is a rectangle that has to read evenly from the road, usually lit from the base. Throw distance, aiming points and the brightness of the surroundings decide whether it reads as a sign or as a bright patch.
Specification
What the sheet states for this build, and what is confirmed per project.
| Topic | What the sheet states |
|---|---|
| Throw | Distance from the base to the face, and the angle it sets |
| Uniformity | Across the face, corner to corner |
| Optic | Narrow, matched to the throw distance |
| Aiming points | Two or four, from the base or from a catwalk |
| Spill | Controlled behind the structure |
| Control | Photocell and timer, often with a curfew |
| Housing | Corrosion class for the position |
| Access | Lamp change without closing the site |
| Data sheet | Current revision, naming the delivered model |
The brightness of a lit sign is relative to its surroundings. A sign that measures correct in a dark field can look dull beside a lit shopfront, which is why the site is surveyed at night before the aiming is fixed.
The geometry of a lit rectangle
A sign lit from the base is lit from below, so the bottom edge is close and the top edge is far. Without correction the face reads bright at the bottom and dim at the top, which is the same falloff a facade has, on a surface that people read as an image.
Two aim points at the lower corners, crossing toward the top, are the common answer. Four points give a flatter field on a wide face. Which one is needed depends on the aspect ratio and the throw, and it is worth modelling rather than guessing.
- Face dimensions and the throw distance from the base.
- Two aim points or four, and whether a catwalk exists.
- The night surroundings, photographed.
Spill behind the structure
Billboards stand in fields, on roofs and beside roads, and the light that misses the face lands behind the structure. That spill is a complaint from a neighbour and a planning condition in many places, and it is fixed by the optic and the aim, not by a shield added later.
A narrow optic aimed with a slight upward bias keeps the beam on the face and cuts the overshoot. Where the sign is close to a boundary, a shield or a louvre is the honest answer, and it costs less than a re-aim after the complaint.
- What is behind and beside the structure.
- Whether the optic can be shielded, and at what cost.
- The aiming drawing, with the beam footprint on the ground.
Running cost and the curfew
A lit sign runs every night of the year, so the running cost is a design input rather than an afterthought. Dimming after midnight, or switching off where the local rule allows it, changes the lifetime cost more than the fixture choice does.
The control is usually a photocell with a timer, and the common failure is a photocell looking at its own light or at a street lamp. Position it where it sees the sky, and check it at commissioning.
- The curfew rule, and whether dimming is allowed instead of switching off.
- The photocell position, away from its own installation.
- A maintenance interval, and who does it.
Before the order
- Throw measured on site, not from a drawing, because the base position moves.
- Aiming drawing with the footprint, for the planning file.
- Photocell position, checked at commissioning.
- Build
- Advertising flood light
- Line
- Flood lights
- Ask for
- Specification sheet, photometric file, aiming drawing
Send the space, get the sheet.
Build, specification sheet and the option list for each line item, in one reply.