Double Insulation Basics

Steps:

• Double insulation uses two layers of non-conductive material to separate live parts from the user, eliminating the need for an earth wire (P correct).
• This dual insulation prevents electric current from reaching the user if one layer fails, protecting against shocks (Q correct).
• Fuses remain essential in these circuits to protect against overcurrent and fire hazards, regardless of insulation (R incorrect).
• Thus, only P and Q are accurate, corresponding to option B.

Why B is correct:

• Double insulation is defined as two independent insulating barriers that provide equivalent safety to earthing, per electrical standards like IEC 60335, while fuses handle overloads separately.

Why the others are wrong:

• A includes R, but fuses are still required for circuit protection.
• C excludes Q, but double insulation inherently prevents shocks.
• D excludes P, but the dual layers replace the need for earthing.

Final answer: B