WiremanWireman · Sparks when plugging in: troubleshooting for electricians · 2023 NEC ·
Sparks when plugging in
A tiny flash can be normal. A pop, soot or sparks while plugged in are not.
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How it works
When a plug meets the contacts while the appliance is drawing current, current jumps the last tiny gap for a split second and makes a small blue flash. Power supplies, TVs, computers and motors draw a burst of current when they first connect, so a small spark is normal for them even when switched off. A loud pop, a big orange flash, soot or a tripped breaker means a short or a failing contact.
Every question and answer in this guide. Tap “Step by step” to walk through it.
- What did the spark look like?
- Tiny blue flash, no soundWas the appliance switched on when it was plugged in?
- Yes, it was onA normal spark from plugging in a running load
- No, it was offDoes it have electronics, a power supply or a motor?
- YesNormal inrush current from electronics
- No, it’s a simple lamp or heaterTest: Inspect the plug and the receptacle
- Plug is pitted, blackened or looseA damaged plug or cord
- Plug looks fine, receptacle is markedA worn or damaged receptacle
- Loud pop, big flash or sootDid a breaker or GFCI trip?
- Yes, something trippedA short in the plug, cord or appliance
- No trip, but there are black marksTest: Inspect the plug and the receptacle
- Plug is pitted, blackened or looseA damaged plug or cord
- Plug looks fine, receptacle is markedA worn or damaged receptacle
- Sparks while it’s plugged in or when the plug wigglesArcing at a loose contact
- Tiny blue flash, no soundWas the appliance switched on when it was plugged in?