In a recent production involving a bar as a set piece, the lighting designer wished to place small lamps in a false ceiling. MR16 lamps were chosen because of their small size and low price. Since budget was a major constraint, purchasing lamp holders was out of the question. After pondering the problem, this solution was developed.

FIGURE 1: THE ASSEMBLED MR16 LAMP HOLDER

CONSTRUCTION SEQUENCE

1. Adjust the centering bit in the hole saw so that the blade protrudes farther than the bit.

2. Turn one soda can upside down and center the hole saw over the can’s stacking ring. Gently drill out the bottom of the can. Repeat this step on the second can. Lacking a drill press, the drilling can be done by hand since the saw tends to center itself on the can.

3. Smooth the edges of the drilled-out cans with the round file.

4. With the tin snips, cut halfway down each can from its top. Then cut away the top half of each can, being careful not to leave a jagged edge on the bottom half (the part you want to keep).

5. Place one of the cans, bottom up, on a table. Place the MR16 lamp, base down, on the cutout of the can with the lamp’s flange resting on the can.

6. Using steady and even pressure, carefully push the second can over the first until the lamp’s flange is sandwiched between the two cans.

7. Connect the MR16 connector to the lamp pins.

MOUNTING

Fastening the completed lamp holders to a set piece depends largely on the piece itself. Hose clamps have been used to attach the lamp holders to dowels mounted in the set piece. Overhead mounting techniques can involve cutting a hole slightly smaller than the diameter of the cans into the set piece. This way the stacking rim protrudes slightly, and the cans rest on the piece itself. Gaffers tape has been used, though the heat of the lamps tends to gum the adhesive fairly quickly. Holes drilled in the cans will allow them to be screwed or bolted to the edge of a set piece.

WIRING NOTES

In our production, 12-volt, 50-watt lamps were used, wired in series to avoid having to use a transformer. Three strings of five lamps each were connected to their own proportionally patched dimmer in order to prevent overpowering them. Wiring five 12-volt lamps in series produced a load of 60 volts. Connecting them to a 120-volt dimmer proportionally patched at 50% insured that they would be powered correctly. If the dimmer allowed the lamps to see a full 120 volts, they would burn out, very quickly.

FIRE SAFETY PRECAUTIONS

MR16 lamps generate a great deal of heat. Users should take care that the lamp holders themselves and the surrounding scenery are designed and treated appropriately. Specifically, in building the lamp holders, cut away as much of the can as possible to minimize the amount of confined space. Use THHN wire rather than zip cord in wiring them. In installing them, do not allow them to be completely enclosed within a set piece. Any surrounding scenery should be designed to promote rather than inhibit the free circulation of air and must be flame-proofed.

FINAL COMMENTS

The major drawback to this design is losing a lamp. If the lamps are wired in a series, all lamps in that string go out if one goes bad. Once the bad lamp has been identified, the entire holder must be removed from the set piece and thrown away since it is next to impossible to disassemble the holder and keep the cans usable. It is recommended that a few spares be made at the time of constructing them in case of emergencies.

As to cost, though building them seems labor-intensive, these lamp holders are obviously cost-effective from a materials standpoint, and some organizations will find them cost-effective in time as well. Drilling the cans takes mere minutes; cutting them around the middle takes a bit longer but is still relatively quick. Assembly takes almost no time at all. Though soda cans tend to crush easily, one learns how to pressure fit the cans quickly after just a little practice. Thus, theatres with limited budgets and inexpensive labor forces will find these lamp holders doubly attractive.