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Value of Insulation Resistance should be?
More than 1 Mohm
Less than 1 Mohm
Equal to 1 Mohm
Can't say
More than 1 Mohm
According to the Indian Electricity (IE) Rules and Bureau of Indian Standards (BIS), the insulation resistance of an electrical installation must be maintained at a high value to prevent leakage current and electrical shocks. The minimum safe limit for domestic or industrial electrical wiring is generally specified as 1M╬й to ensure the safety of personnel and equipment.
According to the Indian Electricity (IE) Rules and Bureau of Indian Standards (BIS), the insulation resistance of an electrical installation must be maintained at a high value to prevent leakage current and electrical shocks. The minimum safe limit for domestic or industrial electrical wiring is generally specified as 1M╬й to ensure the safety of personnel and equipment.
RinsulationтАЛ=IleakageтАЛVтАЛ тАФ fundamental relation for insulation resistance
IleakageтАЛтЙд10┬░6VтАЛ тАФ condition for maintaining safe insulation
Insulation resistance acts as a high-impedance barrier between current-carrying conductors and the earth/ground. By Ohm's Law, IleakageтАЛ=RinsulationтАЛVтАЛ. If RinsulationтАЛ is low, the leakage current increases significantly, which can lead to heating, insulation degradation, or hazardous potential on metallic enclosures.
High insulation resistance is mandatory to minimize leakage currents.
The value is tested using a Megger (insulation tester) at a rated DC voltage.
Moisture and aging of cable insulation decrease the resistance value.
IE Rule 48 specifies the requirements for insulation resistance in fixed installations.
Prevents fire hazards due to insulation breakdown
Ensures safety of personnel against electric shocks
Requires periodic maintenance and testing
Sensitive to environmental factors like humidity and temperature
Domestic wiring certification
Industrial machinery safety audits
Cable health monitoring in power systems
In practice, the resistance is calculated based on the number of outlets; however, 1M╬й is the universal benchmark for testing compliance.
Option B (Less than 1 Mohm) indicates a faulty insulation state prone to leakage current.
A is correct тАФ The insulation resistance of an electrical installation should be greater than 1M╬й to ensure electrical safety and minimize leakage.
Always remember that insulation resistance is measured using a DC source (Megger), not AC, to prevent the influence of cable capacitance.