In this article Jim Fleming discusses the best color to use for signs at night. When there is a beige or a light colored background, people often think that black Channel letters will provide maximum visibility at night.
But the truth is the opposite. Black is opaque and restricts any light to go through the face. As a result, lit signs with a black face are least visible. The best color for maximum night visibility is white. White lights up the brightest at night and as mentioned in the article, white reflects all colors of the light spectrum. Another good tip mentioned is to add a secondary color to the white letters. Maybe adding color to the kind of business or in the logo. Here is a night picture of channel letters with white faces.
White may not work for all businesses, but we can definitely find a color that will give your sign high visiblity at night.
Photo courtesy: Directsignwholesale