easyMultiple ChoiceObjective-mapped
How to Safely Discharge Residual Power in a Desktop PC
A technician is installing a new power supply in a desktop computer. After unplugging the system, what should the technician do before touching any internal components?
Quick Answer
The correct step is to press and hold the power button for 10 seconds after unplugging the system, then wear an ESD strap. This action safely discharges residual power stored in the power supply’s capacitors and other components, eliminating the risk of electric shock or accidental short circuits when you touch internal hardware. On the CompTIA A+ Core 2 220-1202 exam, this question tests your understanding of proper power-down procedures and electrostatic discharge prevention—a common trap is thinking that simply unplugging the PC makes it safe, but capacitors can hold a dangerous charge for minutes. Remember the memory tip: “Unplug, then press—drain the stress; strap your wrist, avoid the twist.” This sequence ensures you discharge residual power before touching components, protecting both you and the sensitive electronics.
⚠ Common exam trap
CompTIA often tests the misconception that simply unplugging the system makes it safe to work inside, or that removing the CMOS battery is the correct way to eliminate all power, when in fact the primary danger is the residual charge in the power supply capacitors.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Press and hold the power button for 10 seconds to drain residual charge, then wear an ESD strap.
Pressing and holding the power button for 10 seconds after unplugging the system discharges the remaining charge in the power supply capacitors and other components, reducing the risk of electric shock or damage. Wearing an ESD strap then provides a path to ground for static electricity, protecting sensitive internal components from electrostatic discharge.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Wear a grounding strap and immediately open the case.
Why it's wrong here
While a grounding strap is good, the technician should first discharge residual power by pressing the power button.
- ✓
Press and hold the power button for 10 seconds to drain residual charge, then wear an ESD strap.
Why this is correct
This discharges the capacitors and reduces shock risk; the ESD strap then prevents static damage.
- ✗
Spray the interior with compressed air to remove dust before touching anything.
Why it's wrong here
Compressed air is for cleaning, not for safety; it does not discharge capacitors and could blow dust into sensitive areas.
- ✗
Remove the CMOS battery first to ensure no power remains.
Why it's wrong here
Removing the CMOS battery does not discharge the main capacitors in the power supply; pressing the power button is the standard method.
Go deeper
Related to this question
Learn chapter
Remote Desktop Protocol (RDP)
Key term
Electrostatic discharge
Electrostatic discharge (ESD) is the sudden flow of electricity between two objects with different electrical charges, often caused by built-up static electricity, which can damage sensitive electronic components.
Key term
ESD
Electrostatic Discharge is the sudden flow of electricity between two electrically charged objects caused by contact or an electrical short, which can damage sensitive electronic components.
About these practice questions
Courseiva writes every 220-1202 question from scratch — 495 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way this is tested on 220-1202
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A technician is replacing a power supply in a desktop computer. After unplugging the unit, what additional step should be taken to ensure personal safety before touching internal components?
medium- A.Wear an anti-static wrist strap.
- ✓ B.Press and hold the power button for 10 seconds.
- C.Remove the CMOS battery.
- D.Unplug all peripheral cables.
Why B: After unplugging the power supply, pressing and holding the power button for 10 seconds discharges residual electrical charge stored in the system's capacitors (especially in the power supply and motherboard). This step, often called a 'parasitic drain,' ensures that no stored voltage remains that could cause an electric shock or damage components when touched. It is a standard safety practice before working inside a desktop computer.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1202 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1202 exam.