Intech Blog

Why Is Your Business Sign Flickering or Going Dark?

Published October 9, 2026 · Intech Corporation · Twin Cities, MN

A business sign that flickers, dims, or goes dark in one section is usually telling you something about the power behind it, not just about the LEDs or neon you can see. Sometimes it's a failed driver or a burned-out module inside the sign itself. Other times the real problem is sitting in the wall behind it, in the circuit, the connections, or the disconnect switch that's supposed to protect whoever services it. Figuring out which one you've got determines whether you call a sign company or a licensed electrician.

Twin Cities business owners notice this stuff more in the fall. Days get shorter, daylight saving time ends soon, and a sign that's half-lit or flickering at 5:30 p.m. is suddenly a lot more visible to every car driving past. A pylon sign, a channel letter storefront sign, or an illuminated monument sign are all built around the same basic electrical chain: a power feed, a disconnect, a driver or transformer, and the light source itself. When something in that chain starts failing, the symptom you see on the sign face doesn't always point straight at the cause.

Intech handles the electrical side of commercial signage across the metro, from troubleshooting a pylon sign that's gone dark on one panel to tracing a flicker back to an overloaded circuit in the building. Here's how to tell what you're actually dealing with.

What's actually failing inside the sign

Most sign lighting problems come down to one of a few parts. A single dark letter or dark rectangle on a larger display is often a failed LED module or a bad connector, since LED segments typically run in their own small sub-circuits and one failure doesn't usually take down the whole sign. A whole letter or whole section going completely dark more often points to a failed driver or power supply, a blown fuse, or a broken wire connection feeding that section rather than the diodes themselves.

Flickering is a different animal. It usually means an unstable power source or a loose connection somewhere in the circuit, and a failing driver can cause intermittent output especially right at startup. Moisture getting into the housing is another common culprit, since it can create a short that comes and goes as humidity and temperature change, which is part of why Minnesota's wet, freeze-thaw fall and spring seasons tend to shake loose problems that were marginal all summer.

When the sign isn't the problem, the circuit is

Here's the part a lot of business owners miss. If you've replaced the driver, swapped LED modules, and the flickering comes right back, the issue probably isn't in the sign at all. It's in the wiring and the circuit supplying it. A sign installed years ago for a smaller, lower-wattage display can end up undersized once it's upgraded to a brighter LED retrofit, and nobody goes back and checks whether the circuit feeding it can actually handle the new draw without a voltage drop that shows up as flicker.

This gets more likely if the sign's circuit was ever added onto a panel that was already carrying a full load. If your building has been through electrification upgrades or added equipment over the years, it's worth having someone check whether your panel still has the capacity to run everything on it cleanly, signage included.

The code requirement most business owners don't know about

Electric signs and outline lighting fall under their own section of the National Electrical Code, and one of the core requirements is a dedicated disconnect switch for the sign's circuit. That disconnect has to be externally operable, has to open all the ungrounded conductors at once, and generally needs to be located within sight of the sign, or lockable in the open position if it isn't. The point is simple: whoever services that sign, whether that's a technician swapping a driver or a firefighter responding to a call, needs a fast, obvious way to kill power to it without guessing which breaker in the panel does the job.

A lot of older commercial signs, especially ones that have changed hands or been retrofitted more than once, are missing this or have a disconnect that's been buried, relabeled, or wired incorrectly. That's not something a sign installer typically catches, because it's an electrical code issue, not a signage one.

Sign company or electrician: who actually fixes this

Most sign companies are good at diagnosing and replacing the components inside the sign cabinet itself. Far fewer of them hold an electrical contractor's license, which means once the problem traces back past the sign's power supply into the building's wiring, the breaker, or the disconnect, they're not the ones who can legally or safely fix it.

If you've already had the sign company out, replaced parts, and the flicker or dead section keeps coming back, that's the signal to bring in a licensed electrician who can test the circuit, check load and connections back to the panel, and confirm the disconnect is installed and labeled correctly. It's the same kind of routine check that commercial buildings already do for exit lighting on a testing schedule; signage just doesn't get the same attention until it's already failing.

• Whole letter or section completely dark: usually a driver, fuse, or wiring failure behind that section
• Individual dark or dim LEDs within a letter: usually a failed module, often not urgent but worth tracking
• Flickering that returns after parts are replaced: likely a circuit, voltage, or connection issue upstream of the sign
• No visible, accessible disconnect at the sign: a code and safety gap worth having an electrician address

What a proper electrical check on a sign circuit covers

A real diagnostic goes past just swapping the obvious part. An electrician checks voltage at the sign's power supply under load, inspects the branch circuit and connections back toward the panel, confirms the circuit isn't shared with something else that's dragging it down, and verifies the disconnect is present, accessible, and correctly labeled. For pylon signs especially, that often means checking underground or pole-run wiring too, since those runs take a beating from frost heave and moisture over the years.