An electronic message center (EMC) is a sign whose text or images change electronically, like an LED reader board. The International Sign Association defines the equipment. Whether your district allows one, and how it may behave, is a separate question the local code answers.
How one real code handles it
Richmond Heights, Ohio gives EMCs their own section, 1179.065. The timing rule is specific:
“Each message shall remain fixed for a minimum of ten (10) seconds, and individual messages shall be separated by a three (3) second pause, during which pause a still image or blank screen shall be shown.”
The same section adds more that belongs in a spec:
- EMCs are allowed only as ground signs, one per parcel, and the whole message must change at once. No flashing, scrolling or animation.
- They must be at least 200 feet from any residential district. Inside a residential district, such as on a church or school parcel, they must also be 200 feet from any lot line between a residential use and a nonresidential one. Between 100 and 200 feet is allowed only if the sign is lit no longer than 6:00 a.m. to 10:00 p.m.
- The owner must be able to dim the display manually and automatically, and it must adjust to ambient light.
- The brightness cap is 0.3 foot candles above ambient, measured at the distances the ISA recommends for the display size. The manufacturer must certify the sign won't exceed the permitted values before the permit is issued.
One detail worth catching: the ordinance calls the cap a “maximum luminance level” but states it in foot candles. Foot candles measure light landing on a surface, not light coming off the sign face. Write the unit and the measuring method into the spec, not just the word. (Ord. 23-2014, passed May 13, 2014. We read it on September 28, 2026.)
What to settle before choosing hardware
- Hold time: how long each message stays still.
- Transition: how one message changes to the next, including any required pause.
- Motion: whether anything may move within a message.
- Light output: the unit, the measuring distance, dimming controls and test conditions.
A report field left empty for electronic signs does not mean the code is silent or that a display is allowed. Use the digital-display checklist and the brightness guide.