(1) Except as otherwise provided in this subsection, externally illuminated signs shall be illuminated only with steady, stationary, fully shielded light sources directed solely onto the sign (but not onto the sign structure, to the extent possible) without causing glare. Light shielding shall ensure that the lamp or light source is not visible beyond the premises and shall further ensure that the light is contained within the sign face.

(2) A light fixture mounted above the sign face may be installed with its bottom opening tilted towards the sign face; provided, that (A) the bottom opening of the light fixture is flat, and (B) the uppermost portion of the fixture's opening is located no higher than the top of the sign face. Light fixtures aimed and installed in this fashion shall be considered fully shielded.

(1) Internally illuminated signs shall be constructed with an opaque background and translucent text and symbols. If the sign owner or owners desire to have the entire sign face visible at night, an external light source may be used to illuminate the sign unless otherwise provided in this chapter.

(2) The difference between the off-message and solid-message measurements using the EMC measurement criteria shall not exceed three-tenths foot-candles at night, utilizing the recommended ISA methodology to determine compliance.

(3) All allowable EMCs shall be equipped with a sensor or other device that automatically determines the ambient illumination and be programmed to automatically dim according to ambient light conditions, or that can be adjusted to comply with the three-tenths foot-candle measurements.