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From time to time (not always but often enough) when I plug my laptop's charger in the wall outlet it makes a spark (even if I use different outlets it's the same).

Why does it do this? Is this a normal behavior? Is it not? Can this damage the charger, laptop or electrical installation? Is it safe?

I'm in Europe. Electrical outlet gives 220V/50Hz (from a pretty old aluminum electrical installation) while the charger is a 65W AC Adapter with 100-240V, 50-60Hz, 1.5A input and a 19.5V, 3.34A output.

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It's just overzealous electrons, that can't wait to get into your laptop. –  Tester101 Oct 18 '13 at 12:15
    
It's because you're in Europe and don't have a switch on your wall outlet ;-) –  RedGrittyBrick Oct 18 '13 at 13:10
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2 Answers

up vote 4 down vote accepted

It can indeed be "normal" for a small brief spark to be seen or heard, when plugging in or removing a plug.

Plugging in.

Electricity desperately wants to get home, and will go to extreme measures to do so. Inside your receptacle electricity waits, patiently biding its time. As you bring the plug closer to the receptacle, the electricity can see a way home and gets really excited. Once the plug gets close enough, the resistance of the air is no longer great enough, and the electricity is able to jump the gap. As the electricity jumps the gap, it shows its excitement by releasing light and sound.

Pulling the plug

Similarly, when something is plugged in, the electricity is running through the circuit on it's way home. As you pull the plug, some of the electricity makes a last-ditch effort to get home. Again it jumps the gap, and releases the familiar excitement light and sound.

Safety

This type of arcing happens; to some extent, in every electrical appliance that connects and disconnects an electrical circuit. The points at which the arc contacts do suffer a small amount of damage, but can typically withstand many arcs without failure. Devices that consistently see larger than normal arcing, typically employ some form of arc suppression or protection. For example, circuit breakers commonly have some form of arc suppression, or protection.

When to worry

  • If the arcing is continuous, even when the plug is inserted fully
  • The arcing occurs when nothing is plugged in, or being plugged in or unplugged.
  • The spark is large (in brightness, sound, duration, and/or length).

Precautions

  • Keep flammable objects away (curtains, furniture, petrol, etc.)

Further reading:

Electric arc
Electrical breakdown

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Why does it do this?

It's because the charger has a low impedance and because the prongs in the plug or the contacts in the outlet are dirty, corroded, worn or loose.

Is this a normal behavior?

No it is not normal, but it isn't especially rare.

Is it not?

Yes it is not.

Can this damage the charger, laptop or electrical installation?

It is unlikely to cause damage to the charger or the laptop. Sparking can erode the contacts (plug pins or outlet contacts) but this is a minor problem if it only happens when you initially push the plug in.

Is it safe?

Nothing in life is safe, there are only degrees of safety. Sparks can set fire to things. Sparks are a possible symptom of a bad contact that may be causing heat that can lead to failure or fire. it is preferable (and safer) to have connectors that don't cause noticeable sparks.

Since you are concerned and outlets and plugs are cheaper than today's lunch, I would replace both.

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