For a fire department connection sign, what does 'engraved letters' imply?

The term 'engraved letters' refers to letters that are physically carved or etched into a material. This method of creating letters ensures durability, as the letters become a permanent part of the surface and are less likely to wear off or fade over time. This is particularly important for fire department connection signs, as they need to be easily identifiable and legible in various conditions, especially during emergencies.

Engraved letters maintain their visibility without depending on external conditions like lighting or power sources, unlike illuminated letters, which require a power source to function effectively. Additionally, engraved letters can't be easily removed or replaced, ensuring consistency in identification. This permanence is vital for first responders who need to locate fire department connections quickly and accurately.