WiremanWireman · Outlet warm, discolored or smells hot: troubleshooting for electricians · 2023 NEC ·
Outlet warm, discolored or smells hot
Tell normal warmth under a heavy load from a loose or failing connection that can start a fire.
Before you start
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How it works
A plug’s current passes through spring contacts in the receptacle, then through the terminal screws or push-in holes to the circuit wires. A good connection makes very little heat. A loose screw, worn contact or push-in connection adds resistance, and resistance carrying 10 to 15 A makes real heat in a small spot, enough to brown the plastic and eventually start a fire. Receptacles also pass current through to the outlets after them, so one can heat up with nothing plugged in.
Every question and answer in this guide. Tap “Step by step” to walk through it.
- What do you notice?
- Slightly warm with something plugged inWhat’s plugged in?
- A heater, hair dryer or other heat applianceUnplug it. Is the plug hotter than the receptacle face, or the other way around?
- The plug and cord are hotterA worn or damaged appliance plug
- The receptacle is hotterTest: Open the box and inspect the connections
- Wires in push-in (back-stab) holesA failing push-in connection
- A loose or darkened screw terminalA loose screw terminal
- Aluminum wire (dull silver)Aluminum branch wiring on a device not made for it
- Connections tight and cleanWorn receptacle contacts
- Both only slightly warmNormal warmth from a heavy load
- Several things on a power stripToo much plugged into one receptacle
- Something small, like a lamp or chargerTest: Open the box and inspect the connections
- Wires in push-in (back-stab) holesA failing push-in connection
- A loose or darkened screw terminalA loose screw terminal
- Aluminum wire (dull silver)Aluminum branch wiring on a device not made for it
- Connections tight and cleanWorn receptacle contacts
- A heater, hair dryer or other heat applianceUnplug it. Is the plug hotter than the receptacle face, or the other way around?
- Hot, discolored, melted or smellsA failed, overheating receptacle
- Warm with nothing plugged inTest: Open the box and inspect the connections
- Wires in push-in (back-stab) holesA failing push-in connection
- A loose or darkened screw terminalA loose screw terminal
- Aluminum wire (dull silver)Aluminum branch wiring on a device not made for it
- Connections tight and cleanWorn receptacle contacts
- Slightly warm with something plugged inWhat’s plugged in?