Final answer:
The minimum temperature rating of fixture wires in show window luminaires cannot be determined without the specific local code or T11 document. For other light-related questions, two filaments are required for three power settings on light bulbs, and the operating voltage of series-wired holiday lights depends on the number of functioning bulbs.
Step-by-step explanation:
The minimum temperature rating for fixture wires used in show window luminaires, which are closely spaced and connected together, is specified in the National Electrical Code (NEC). However, as the question may be referring to a local code or a specific set of installation instructions (like T11), without that specific information it's not possible to provide an accurate minimum temperature rating. One must consult the local electrical codes or T11 document directly to determine this. Generally, wire temperature ratings must match or exceed the maximum operating temperature of the fixture, which is often around 90°C, but this can vary based on fixture design and local regulations.
For the other aspects of light-related questions raised here, let's provide a brief overview of a few concepts:
- Light bulbs with multiple power settings require at least two filaments for three power settings. By switching these filaments on or off, or combining them, different power levels can be achieved.
- In the case of series-wired holiday lights, if one bulb designed to behave like an open switch burns out, the entire string of lights will go out because the circuit is interrupted. In such a string with 40 bulbs on a 120 V supply, each bulb would normally operate at 3 V. If a bulb behaves like a closed switch (short circuits) when it burns out, the remaining bulbs will still operate, and the operating voltage for each bulb in a 39-bulb string will slightly increase since the voltage is now divided among fewer bulbs.
- The resistance of filament in a heat lamp can be calculated based on its power rating and the voltage applied, using Ohm's law.