Sign Installations: Fluorescent-to-LED illumination retrofits

15 February 2018


Photo courtesy Vistex Graphics

By J. Bryan Vincent
Ten years ago, the sign industry went through a major conversion cycle in which light-emitting diodes (LEDs) displaced neon as the incumbent technology for illuminating channel letters. Given the relatively high costs of neon, its power requirements, its ongoing service needs and the risk of breakage, the benefits of switching to solid-state, longer-lasting, energy-efficient LEDs were compelling.

As existing signs were converted, the process varied, from (a) removing just the neon lighting itself and applying LED modules within the letters on-site to (b) pulling the letters down completely and replacing or refacing them in a sign shop to (c) replacing the sign outright with a new set of letters.

The choice of approach depended on the location, the size of the sign and other factors. So, a variety of approaches were taken. With larger signs where the letters could not be pulled down cost-effectively, routed sub-panels were often prepopulated with LEDs and then inserted into each letter on-site, to help minimize installation time and costs.

Today, the sign industry is in the early stages of a second wave of the conversion cycle, where T12 high-output (HO) fluorescent lamps in sign cabinets are being replaced with LEDs. In fact, there are already a vast number of systems available in the marketplace for retrofitting single- and double-faced sign cabinets of any depth.

A different equation
Compared to channel letters, retrofitting a cabinet sign is a bit of a different equation. For one thing, the underlying fluorescent illumination source is already much less expensive, lasts longer and is much more efficient than neon. Other than smaller wall signs, cabinets are larger than letters, which may make them impractical or even impossible to take down, suggesting the need for on-site work.

Fortunately, sign cabinets use fixed-length T12 HO lamps. The spacing of these lamps lends itself to the easy installation of low-cost LED products that also take advantage of fixed units of measurement.

Early ‘carpet’ or ‘ladder’ LED systems for sign cabinets were primarily developed for newly constructed signs. While they were relatively fast and easy to install at a sign shop, they proved cumbersome in the field, especially for installers working from a bucket truck. As a result, many signmakers opted instead to simply adhere LED modules to an extrusion and then fix it inside the cabinet.


Today, many sign cabinets’ T12 HO fluorescent lamps are being replaced with LEDs.
Photos courtesy Principal LED

The relamping approach
More recently, retrofits have been migrating toward systems where LEDs can fit directly into double-recessed T12 sockets. These systems typically come in two varieties.

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The first is a self-ballasted LED tube. The power supply is contained inside the LED tube, so the existing ballast is bypassed. The socket is still used to supply primary power.

The second variety is a preassembled ‘stick’ with (a) LEDs that fit directly into the socket and/or (b) an extrusion carrying the LEDs with an end cap that mates to the socket.

As both of these varieties offer the benefit of using the socket as a holder for the LED system, they enable the undertaking of a T12-to-LED retrofit installation that is very similar to a simple relamping.

The first option offers the benefit of no extra wiring. Self-ballasted LED tubes typically integrate low-cost power drivers, however, which can be problematic given the lack of a heat sink (i.e. a passive heat exchanger, which transfers and dissipates the heat away from the device) and the types of components used. The second option does require additional wiring, but uses an external, commercial-grade power supply, which increases the system’s reliability.

It is worth keeping in mind any power supply, due to its complexity and number of components, is much more likely than an LED to fail. So, maintenance is easier if they are kept separate.

Given these factors, the preassembled LED sticks are becoming the preferred option for retrofitting cabinet signs previously illuminated by T12 fluorescent lamps.

“Many signmakers want a simple solution, where retrofitting is just like relamping,” says Daryl Foreman, vice-president (VP) of sales for Principal LED. “LED sticks are available in any standard lamp length, with both single- and double-sided versions.”

Moreover, these systems can be customized to meet any specific requirements in terms of depth, length, colour temperature and beam pattern, overcoming earlier limitations.


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.

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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.


The sign’s dimensions, depth and face material will affect the choice of products to illuminate it.
Photo courtesy Vistex Graphics

The tools for the job
Another important consideration before undertaking a T12-to-LED retrofit is putting together all the required materials in advance of the on-site installation, including tools, wire and wire nuts.

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Some of the aforementioned LED ‘sticks’ come preassembled with wire whips, making it easier to tie them with enough wire back to the power supply. These certainly save time on-site.

When using a ladder or carpet system, on the other hand, where some assembly will be required, it is a good idea to do as much of this work as possible in the shop, before going on-site. Assembly is always easier in the shop than on a truck or out in the elements.

For smaller, single-sided signs, signmakers may well prefer to install separate ‘peel and stick’ LED modules on the back of the existing cabinet, rather than use a preassembled system. In these cases, it is still important to have designed the layout in advance, based on the sign’s dimensions and face material. And choosing higher-power modules, especially those with wide optics, will be beneficial in reducing the sheer amount of on-site peeling and sticking.

“There are now simple LED solutions for single-face cabinets that can light a 6 x 6-m (20 x 20-ft) surface from a depth of 150 mm (5.9 in.) with just one 6-W module,” says Carlos Vilanova, owner of Global-Lux, an LED system provider based in Boucherville, Que.

Another tip before installing any peel-and-stick LED modules is to make sure the surface is free of debris and has been cleaned with a non-oil-based solution. It is also a good idea to attach the LEDs mechanically or with a minimum of silicon to the back of the sign, wherever possible.


A single 6-W module can now light a 6 x 6-m sign face from a depth of 150 mm.
Photo courtesy Global Lux

Calculating value
Many LED vendors can also equip signmakers with the tools to help sell retrofit jobs to their customers. The more understanding there is of the value a conversion can bring, the better the chance of closing the sale.

In addition to outlining some of the obvious benefits of LEDs, it is a good idea to calculate the overall return on investment (ROI). Online tools allow users to input the number of LEDs, the hours of illumination per day and local electricity prices, then produce a summary of the relevant energy and maintenance savings. They can also help when determining the markup of material costs.

There are many fluorescent lamps still illuminating sign cabinets today, which represent a major opportunity to maximize the use of existing assets. And it is certainly more profitable to dedicate service teams to installing entire LED retrofits rather than simply relamping signs with more fluorescent bulbs.

J. Bryan Vincent is a partner at Principal LED, which manufactures LED systems for the sign industry. For more information, visit[6].


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