Final answer:
It is false that a flexible cord or cable should be run through a hole in the ceiling to be concealed behind ceiling tiles as it may not comply with safety codes. High-voltage transmission lines are not insulated, and wood can conduct electricity in the form of lightning due to moisture and sap.
Step-by-step explanation:
Running a flexible cord or cable through a hole in the ceiling instead of through a doorway with the intent of concealing it behind ceiling tiles is false. This method may violate building codes and can pose fire and safety hazards. It is essential to follow local codes and best practices for electrical installations. Cables and cords should be run through appropriate conduits or raceways and installed in compliance with the National Electrical Code (NEC).
Concerning the other questions for reference: High-voltage wires that are connected to metal-frame towers are indeed held aloft by insulating connectors, but it is false that these wires are wrapped in an insulating material. They are typically bare since insulation is not practical for high-voltage transmission lines due to the sheer size and heat generation.
As for wood and lightning, it is true that while wood is an insulator, lightning can travel through a tree to reach Earth. Trees contain moisture and sap, which can conduct electricity, causing lightning to pass through them to the ground.
Last but not least, the statement about tension is true. Tension is a force that acts along the length of a flexible connector such as a rope or cable and pulls equally on the connecting points or loads.