Making and Designing an Internally Illuminated 4×8 Sign
Question: Our church is requesting that some of us “handymen” construct a double-sided internally illuminated sign for the church. Are you able to help us design and build a 4’ x 8’ sign like this?
Answer: That is a loaded question. First, if you are in the US, Canada, or most Western European countries, labels are required on your sign requiring it to be listed with a government agency that has approved you to produce an electrical sign. If you are in a developing nation, it is unlikely that this type of labeling is required, but then, it is also likely that the sign may catch fire and burn up itself and anything it is close to as well.
I can and will, though, tell you how these signs are built in the US, as they are really quite simple.
First, a steel or aluminum frame, typically using angle iron (steel) or aluminum are welded into the shape of a sign. For a 4’ x 8’ sign, for instance, the depth of the sign cabinet should be about 18”, so as to avoid “hot spots” when viewing the sign at night. Hot spots are when you can see the fluorescent light tubes through the opaque plastic as bright spots. If the lamps are eight or so inches away from the opaque plastic, and it is a good material such as polycarbonate or impact resistant acrylic, then you won’t typically see these hot spots.
For the internal part of the cabinet, there may also be a cross member or two added for strength, to keep the sign from twisting in high winds. Usually across the top/bottom or sides of the sign, depending on the orientation of the lamps, sheet metal fabricated tracks will be added with the fluorescent lighting ballasts and sockets for the fluorescent lamps. For a 4’ x 8’ sign that will be mounted on a pole, it would be most likely that 36 inch vertically oriented lamps would be used, in order to allow a pole to be inserted vertically through the cabinet for mounting.
Typically, where a vertical pole will be used, a short piece of steel tubing, maybe 5 or 6 inches in diameter and six inches taller than the cabinet (it will stub out of the bottom of the cabinet to be welded to the main pole later), will be inserted through the cabinet and welded to a bracket at the top and bottom of the cabinet added for attaching the pole by welding.
Now, a “galvaneal” steel sheet metal is typically either spot welded or riveted to the main frame, then a rolled steel sheet metal strip bracket is screwed or riveted to the top and bottom of the cabinet as a retainer for the sign plastic or whatever material will be used (usually high impact acrylic or polycarbonate plastic, especially if the sign will be illuminated from the inside as I have described here.
The electrical wiring will be run into a switch box (waterproof for exterior usage) or to an electronic light sensor that will tell the sign when to come on at dusk and when to shut off at dusk. Most signs that use the light sensor will also have a shut-off switch, but signs that have only the shutoff switch are normally controlled from the electrical panel in the store and are manually lit or shut off.
As stated previously, in the US, you will need to have an Underwriter’s Laboratory label on all electrical signs, and in Canada, a CSA label. Most European countries have similar labeling standards and requirements for electrical items such as internally illuminated exterior and interior signage.
To see more of the other various graphic signs, check in here: http://www.visigraph.com/signs-letters/