Question

The reverse side of a three-pin plug with incorrect connection of wires is shown in the diagram below.
(a) Identify the fault in the above connection.
(b) Mention a risk factor involved, if the user operates the appliance with correcting it.
(c) Will the appliance function in the present situation? (Yes or No)

Hint:

Always remember the wiring code: Live on the right (fused pin), Neutral on the left, and Earth at the top. Incorrect wiring is a serious safety hazard.

Answer 1

Step 1: Understanding the Concept: 
Standard color coding and positioning for a three-pin plug (viewed from the back): 
- Top pin: Earth (Green/Yellow) 
- Right pin: Neutral (Blue/Black) 
- Left pin: Live (Red/Brown) 
Note: When viewed from the front, L is right and N is left. From the back, it is mirrored.
Step 2: Detailed Explanation: 
In the diagram provided: 
1. The Earth pin (top) is connected correctly (green). 
2. However, looking at the two lower pins from the reverse side, the Red wire (Live) should be on the left and the Blue wire (Neutral) should be on the right. 
The diagram shows the Red wire on the right and the Blue wire on the left. They are incorrectly swapped. 
Step 3: Final Answer: 
The fault is that the Live wire (Red) and Neutral wire (Blue) are connected to the wrong pins (swapped). 
(b)
Step 1: Understanding the Concept: 
Safety devices like switches and fuses are always connected in the Live wire. 
Step 2: Detailed Explanation: 
If the wires are swapped, the switch of the appliance will now be in the Neutral line. 
When the switch is turned 'OFF', the circuit is broken, but the appliance remains connected to the high voltage through the Live wire (which is now connected where the Neutral should be). 
A user touching the internal parts of the "OFF" appliance could receive a fatal electric shock. 
Step 3: Final Answer: 
The main risk is that the appliance remains at a high potential even when switched off, leading to a risk of electric shock. 
(c)
Step 1: Understanding the Concept: 
Most AC appliances require a complete path for current to flow, regardless of the polarity (for simple resistive loads). 
Step 2: Detailed Explanation: 
The appliance requires a potential difference of 220V between its terminals to operate. 
Even with the wires swapped, a complete path exists from the Live terminal through the appliance to the Neutral terminal. 
The current will still flow, and the appliance will work, although it is highly unsafe. 
Step 3: Final Answer: 
Yes, the appliance will function, but it will be extremely dangerous to use.