Older homes are where this question comes up most. The Inquirer notes that much of Philadelphia's housing was built before 1950 and that older homes often have fewer outlets than people need today, which is exactly what tempts people toward power strips and shared circuits.
Plug it into the wall, and give it the circuit to itself
The Consumer Product Safety Commission says to plug a space heater directly into a wall outlet, never into an extension cord or power strip. The U.S. Fire Administration's heater card goes further: do not plug anything else into the same circuit while the heater runs, because that can cause overheating.
An empty second socket on the same outlet does not mean the circuit is free. Other outlets, and sometimes lights, in the same room or the next one can share that breaker. If you don't know what a circuit serves, find out before winter, and label the breakers once you do, as the Electrical Safety Foundation International (ESFI) suggests. Never run two heaters on one circuit.
Warning signs that mean stop, not reset
ESFI and its older-adults toolkit list the signs that call for a licensed electrician:
- Breakers that trip often, or fuses that blow
- Lights that flicker or dim when the heater or another appliance turns on
- Outlets or switches that feel warm, look discolored, or crackle, sizzle or buzz
- A tingling feeling when you touch an appliance or switch
Don't keep resetting a breaker to get the heater running again, and don't swap in a bigger breaker or fuse. ESFI says breakers and fuses must be the correct size for the circuit. A warm cover plate is covered in more detail in our guide on warm outlets and switches, and ungrounded outlets in our two-prong outlet guide.
Before each use, check the unplugged heater for a cracked or broken plug or loose connections, as the ESFI toolkit advises. Don't use a damaged heater.
When to have the circuit checked
ESFI recommends an electrical inspection for any home more than 40 years old, and again after adding a major appliance. It also recommends having an electrician add new circuits for high-energy devices rather than overloading existing ones. If a heater is going to be your main heat in a room every winter, ask whether a dedicated circuit makes sense.
Useful questions for the electrician: Which outlets and lights share this circuit? Can it carry this heater per the label rating and the manual? Are the outlet and its connections sound? Is a repair enough, or does it need a new circuit?
What Philadelphia requires for the electrical work
In Philadelphia, L&I's Electrical Permit page says a licensed electrical contractor must perform all electrical work, and the owner or the owner's agent hires a licensed electrical inspection agency for inspections. The permit fee is $25 per $1,000 of estimated cost, with a $63 minimum.
The same page treats some work as minor repair that does not need a permit, including replacing circuit breakers, fuses, switches and receptacles. That still means an electrician does it, not the homeowner. A new circuit for a heater is new installation work, so expect a permit. Our Philadelphia electrical permit guide covers which jobs fall where.
Fire safety after the circuit checks out
A sound circuit handles only the electrical side. The CPSC and the U.S. Fire Administration both say to keep heaters at least 3 feet from anything that can burn, set them on a solid, flat surface away from doorways and walkways, choose one tested by a recognized lab with automatic tip-over shutoff, and turn it off when you leave the room or go to bed. The CPSC counts about 1,600 portable heater fires a year from 2020 to 2022, and it suggests checking cpsc.gov/recalls before using an older heater.
Keep smoke alarms on every level and in each bedroom, and test them monthly. Philadelphia residents can request smoke alarms through Philly 311, according to the city's Office of Emergency Management. Our smoke alarm replacement guide explains when an old alarm should go.