Final answer:
Outdoor spa or hot tubs that are GFCI-protected may be cord and plug connected up to a certain length as per NEC codes. The plastic insulation on wires prevents both shock and thermal hazards, while GFCIs protect specifically against shock by detecting current imbalance. Ordinary breakers and fuses do not prevent shocks as they are designed to guard against overcurrent, not leakage currents.
Step-by-step explanation:
According to the National Electrical Code, packaged spa or hot tubs installed outdoors that are GFCI protected may be permitted to be cord and plug connected, with the provision that the length of such cord should not exceed a specific measurement for safety reasons. While this question does not specify the exact length allowed by the code, it is crucial to refer to the latest edition of the NEC or local building codes for this detail as it can vary depending on the regulations in place at the time of installation.
Plastic insulation on live/hot wires is designed to prevent both shock and thermal hazards. It impedes the flow of electricity, which reduces the chance of an electric shock and prevents the wire from overheating due to electrical current passing through it. However, GFCI (Ground Fault Circuit Interrupter) is specifically designed to protect against shock hazards by measuring the current balance between the live/hot and neutral wires. If there is a difference, such as if one wire is significantly longer than the other, it may cause the GFCI device to trip as a precaution because it suspects a ground fault, even when no hazardous condition exists. Ordinary circuit breakers and fuses are ineffective in preventing shocks because they are designed to protect against overcurrent situations which may result in overheating and fire hazards, not against leakage currents that might lead to electric shocks. GFCI devices fill this gap in protection by actively monitoring for any loss of current to ground that could pose a shock risk.