Final answer:
Exposed live/hot and neutral wires must be insulated to prevent shock and thermal hazards. Insulation prevents direct contact with electricity and undesired heating effects. Circuit breakers and fuses interrupt excessive current to prevent fires but do not prevent shock hazards as effectively as GFCIs.
Step-by-step explanation:
Any exposed live/hot wires and neutral wires MUST be insulated to be considered accessible. This is essential because the plastic insulation on these wires is what safeguards against shock hazards and thermal hazards. Shock hazards occur when electric current passes through a person, which can range from being merely painful to potentially lethal. Plastic insulation prevents direct contact with current-carrying wires, thereby protecting against shocks.
Regarding thermal hazards, electric power can cause undesired heating effects, such as fires, when it is converted into thermal energy at a rate faster than it can be dissipated. A common example is a short circuit due to damaged insulation which can quickly elevate the temperature of surrounding materials and pose a fire risk. Therefore, insulation is vital to prevent both of these hazards.
Circuit breakers and fuses are designed to interrupt excessive currents and thus prevent thermal hazards but are not effective in preventing shock hazards because they do not respond quickly enough to the rapid succession of events that constitute a shock. Conversely, a ground fault circuit interrupter (GFCI) is sensitive to imbalances between the live/hot and neutral wires and will trip even if those wires are of significantly different lengths, which could imply a possible path for current leakage that could result in a shock.