Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
Switch always installed in
Phase wire
Earth wire
Neutral wire
Any of above
Phase wire
In electrical domestic wiring, a switch must always be connected in the phase (live) wire to ensure the circuit is de-energized when the switch is in the 'OFF' position. Connecting the switch to the phase wire ensures that the appliance or load terminal is electrically isolated from the high-potential supply when turned off, preventing accidental electric shocks during maintenance.
In electrical domestic wiring, a switch must always be connected in the phase (live) wire to ensure the circuit is de-energized when the switch is in the 'OFF' position. Connecting the switch to the phase wire ensures that the appliance or load terminal is electrically isolated from the high-potential supply when turned off, preventing accidental electric shocks during maintenance.
VloadтАЛ=VsourceтАЛ├Ч(1тИТS) тАФ where S=1 (switch open) results in 0V across load
The phase wire carries the potential difference relative to the earth. When a switch is placed in series with the load on the phase side, opening the switch creates an open-circuit path, effectively cutting off the flow of current and ensuring no voltage potential exists across the appliance. If placed on the neutral side, the load remains energized at the phase potential even if the switch is off, creating a severe safety hazard.
Switching the phase wire ensures safety by isolating the device from line potential.
The neutral wire should never be switched, as it maintains potential reference but does not control power flow.
Correct wiring practice prevents the 'hot' chassis hazard where appliance metal casings might become live.
Adheres to NEC and BIS wiring regulations for domestic installations.
Ensures zero potential at load when switch is OFF
Prevents accidental shock during lamp or element replacement
Domestic lighting circuits
Power outlets (Socket boards)
Industrial control panels
| Feature | Recommended | Dangerous |
|---|---|---|
Switch Location | Phase Wire | Neutral Wire |
Placing a switch in the neutral wire leaves the appliance at full phase potential even when switched off, posing a risk of electrocution if a user touches the live terminal.
Earth wire should NEVER be switched; it must provide a continuous path for fault current.
A is correct тАФ Switches are always installed in the phase wire to isolate the appliance from the source voltage.
Always verify polarity with a neon tester or multimeter before performing maintenance; never assume the switch position indicates the absence of potential if wired incorrectly.