Sign cabinets are typically larger than channel letters.
Planning for success
Regardless of which particular system is selected for a retrofit, it is important for the installation process to be cost-effective and seamless. With this in mind, there are a few factors to consider beforehand to help make sure the project is successful.
First, due diligence must be taken to determine the exact dimensions, depth and face material of the sign that is to be retrofitted, as this information will affect the choice of the right product. When choosing an LED system that will be plugged into the existing sockets, for example, signmakers should check the distance from the LEDs to the sign face will allow for even lighting, based on the spacing of those sockets.
Deeper sign cabinets may require a more specifically directional LED system, like those that provide a 120-degree Lambertian (i.e. ideally diffused) beam pattern. Shallower cabinets, meanwhile, may need an LED system with specialized batwing-type optics, which are designed to spread the light more laterally.
Most LED suppliers provide depth and on-centre spacing charts. These recommend the maximum spacing between the LEDs’ centres for a given depth of sign cabinet.
Many LED manufacturers also provide layout and estimating services, which can help recommend the right option based on the sign and the site survey. There are online product selector tools with layout capabilities, allowing signmakers to plan how they can best populate a cabinet with LEDs.
Accommodating face changes
It is also important to keep in mind the total depth includes not just the sign cabinet’s own extrusion profile, but also the depth of the sign face. Formed faces, especially, will increase the overall depth noticeably.
There have been situations where a sign retrofit involves changing from a formed face to a flat one, leading to lighting problems. In these cases, the LEDs may need to be placed on closer centres than suggested by the original socket spacing. Many vendors offer special brackets to accommodate these changes. Ultra-wide optics are often a better option for accommodating a shallower profile, however, because they allow the existing sockets to still be used and they help keep costs down by not having to add any extra material.
Another concern is how to optimize LED illumination in a larger sign with a flexible face material. When the wind blows, the flex face can easily be pushed off-centre, leading to spottiness and striping in the lighting. It may be impossible to optimize the placement of the LEDs inside the cabinet to avoid this problem, so instead, a better option is to tie a clear nylon line across the sign to hold the face flat.
