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Which Electrical Appliances Most Often Cause Fires—and How to Prevent Them


October 22, 2025 | Allstar Electrical Services, LLC

Introduction

Electrical fires remain a serious hazard in residential settings. The U.S. Fire Administration (USFA) estimates 24,200 residential electrical fires occurred in 2021, causing more than $1 billion in property loss.

At Allstar Electrical, we frequently encounter overloaded circuits and wiring that quietly run too hot for safety. The most common offenders are extension cords, space heaters, and increasingly high-powered computer or crypto-mining rigs.

This article explains how these everyday devices create risk—and how a simple act like running a space heater and gaming PC on the same 15 amp circuit can exceed safe limits without ever tripping a breaker.

1. Extension Cords and Power Strips: The “Temporary” Wiring Trap
 

Why They’re Risky

Extension cords are meant for temporary use, yet they’re often used permanently to power appliances. This misuse creates fire hazards:

  • Overloaded cords that overheat and melt insulation.
  • Cords under rugs or furniture that can’t dissipate heat.
  • Daisy-chained power strips that increase resistance and voltage drop.

Even UL-rated power strips can fail when loaded with heaters, microwaves, or multiple computers.

Safer Alternatives

  • Use extension cords only temporarily. They are not a substitute for fixed wiring.
  • Avoid plugging major appliances or heaters into them. High-draw devices should always connect directly to a wall outlet.
  • If you routinely need more outlets, add both new receptacles and circuits. Adding more outlets to an already-loaded circuit doesn’t increase total capacity—it only spreads the load to more connection points.
  • Never “upgrade” a breaker from 15 amps to 20 amps without verifying wire gauge.
    • Most 15 amp household circuits use 14-gauge wire, rated only for 15 amps.
    • Installing a 20 amp breaker on that wiring disables the safety margin—the wire can overheat long before the breaker trips, risking melted insulation, arcing, or fire.
    • To upgrade safely, re-wire the circuit with 12-gauge copper and ensure every device on that line is rated for 20 amps.
    • If lights dim or breakers trip when plugging in devices, call a licensed electrician. Allstar Electrical can add properly sized circuits, balance your load, and verify wiring safety.

2. Space Heaters: Small Size, Big Danger
 

A 1,500 W space heater draws roughly 12.5 amps on 120 V—nearly the entire capacity of a 15 amp line. Add a TV or lamp on the same circuit and you’re above the safe continuous-load limit.

The breaker may not trip, but wiring can still overheat, degrading insulation over time. Space heaters are responsible for over 40% of fatal home heating fires, according to USFA.

Safe Use Tips

  • Plug directly into a wall outlet—never a cord or power strip.
  • Keep 3 feet clear of curtains or furniture.
  • Turn off and unplug when unattended or sleeping.
  • If the plug or outlet feels warm, discontinue use immediately.

 3. High-Powered Computers, AI Workstations, and Mining Rigs
 

A Modern Risk Few Consider

Today’s advanced AI workstations, gaming PCs, and crypto miners often use 1,000–1,600 W power supplies—sometimes with multiple GPUs running 24/7. These are continuous loads that can push household circuits beyond their intended duty cycle.

Hidden Overload

A 1,200 W workstation draws ~10 amps. Add monitors and peripherals, and you can hit 13–14 amps—above the NEC’s 80% continuous-load guideline. The breaker might hold, but wiring and outlets can reach dangerous temperatures.

Best Practices

  • Use a dedicated 20 amp or 240 V circuit for heavy-draw devices.
  • Employ properly rated cords and surge protectors (not cheap power strips).
  • Keep rigs off carpets, allow airflow, and monitor outlet temperature.
  • Have an electrician confirm panel capacity before adding more GPUs or AI servers.

Allstar Electrical can install dedicated circuits and verify that your wiring safely supports today’s high-tech workloads.

4. How a 15 Amp Circuit Can Overheat Without Tripping the Breaker
 

Circuit breakers react to excess current, not wire temperature. If a circuit carries 12–14 amps continuously, the wire may run hotter than intended—especially with aging insulation or long runs.

The 80% Rule: continuous loads (over 3 hours) should not exceed 80% of breaker rating—about 12 amps on a 15 amp circuit.

Never replace a 15 amp breaker with 20 amp unless the wiring and outlets are properly rated. Doing so prevents the breaker from tripping when a wire’s lower rating is exceeded, allowing it to melt or ignite.

 5. Allstar Electrical’s Safety Recommendations
 

  • Have a licensed electrician evaluate your panel and branch loads.
  • Add dedicated circuits for heaters, gaming rigs, or workshops.
  • Upgrade old wiring and outlets showing wear or discoloration.
  • Replace any outlet that feels hot or smells burnt.
  • Stop relying on extension cords or daisy-chained strips.
  • Schedule a residential load analysis—available from Allstar Electrical throughout the Denver metro area.

Categories

Frequently Asked Questions

What appliances cause most electrical fires?

Space heaters, extension cords, and high-draw devices like gaming rigs or mining machines.

Why do space heaters cause so many fires?

They use almost all of a 15 amp circuit’s capacity, and combined loads can overheat wiring before a breaker trips.

Can an overloaded circuit start a fire even if the breaker doesn’t trip?

Yes. Breakers sense current, not heat; wiring can overheat long before the breaker reacts.

Are bitcoin miners, AI rigs, and gaming PCs dangerous?

They can be. Continuous 1,000–1,600 W loads need dedicated circuits and good ventilation.

How can I tell if my wiring is overloaded?

Warm outlets, flickering lights, tripped breakers, or burning odors are warning signs. Stop using the circuit and call an electrician.

What can homeowners do to reduce fire risk?

Avoid overloaded circuits, follow heater safety rules, and ensure all high-power equipment runs on properly rated wiring.

Can high-end gaming PCs or AI workstations overload a home circuit?

Yes. Multi-GPU computers can draw close to a circuit’s limit; combine them with other devices and you may exceed safe levels even if the breaker never trips.