Electromagnetic Interference

Castiel's dramatic entrance causes the lights to go haywire.

Electromagnetic Interference is an ability, or a side effect of a supernatural entity's presence that causes nearby electronics to malfunction.

Species with this ability

• Archangels - Raphael's arrival caused a blackout across the entire Eastern Seaboard, while Lucifer caused the lights to flicker with his mere presence at the Elysian Fields Hotel.
• Angels - Angels' true forms counteract electronics. When Angels first appear in vessels, or sometimes when they're near electronic equipment, they can cause lights to flicker, spark, or explode.
• Banshee - A Banshee's presence will cause lights to flicker, similar to ghosts.
• Demons - Demons, like spirits, often disrupt nearby electronics with their presence. Large numbers of demons can cause thunder storms.
• Ghosts - All ghosts disrupt nearby electronics with their presence.
• Shtriga - When a shtriga entered Michael's room, its presence caused interference in the camera feed Sam and Dean were watching.
• Reapers - The appearance of a Reaper can cause lights in a room to flicker or go out. A Reaper was also able to cause a car to lose power and stop.
• Soul Eaters - A Soul Eater's presence will cause light to flickers, similar to ghosts and banshees

Individuals with this ability

• Dean Winchester (formerly) - While he was a Knight of Hell, Dean's presence caused interference in a gas station's security cameras.
• Asmodeus - Asmodeus' presence caused the lights in the room to flicker.
• Azazel - His presence caused lights to flicker, electronic devices to go haywire and clocks to stop. He could also do this at will, and used this to try and fool Dean into giving him the Colt, by making him think he was coming.
• Dagon - When Dagon killed two angels, a nearby security camera was fried.
• Pestilence - Pestilence's face on a security monitor was always masked by static.
• Famine - His presence caused lights to flicker, but his anger made them explode.
• Hydeker - He caused the camera feed that Sam and Dean were viewing to become static when he entered Michael's room.
• Lucifer - His mere presence causes lights to flicker, like in the Elysian Fields Hotel.
• Raphael - His arrival caused a blackout across the entire Eastern Seaboard.

Places with this property

• Men of Letters bunker - People can recieve and send radio and internet signals from there, but cannot be tracked through them.
• Bermuda Triangle - As mentioned by Sam, the region also has similar properties to the bunker, although presumably not in such a convinient/weaponised fashion.