SCP-520

Link to article: SCP-520.
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= **SCP-520** - Knife Switch by [[*user Photosynthetic]]

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**[http://www.scpwiki.com/photosynthetics-personnel-file More by this author]**
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[[include component:acs-peppo-lite

|item-number= 520
|clearance= 2
|container-class= safe
|secondary-class= none
|disruption-class= keneq
|risk-class= notice

]]

**Special Containment Procedures:** SCP-520-1 and -2 are to be stored in an inanimate-item containment locker with standard positive-action defenses. Each object's handle is to remain perpendicular to its base. The handles and contacts must be secured with sturdy clamps made of insulating material.

PoI-520-A and PoI-520-B are to remain in Foundation custody; as long as they do so voluntarily, they are to be accommodated comfortably without communications access. All electrical devices in each PoI's suite should be checked weekly for damage or modification. Should PoI-520-A and PoI-520-B agree to meet, they are permitted one hour of face-to-face or videoconference time per week.

--Tests of SCP-520-2 should be conducted using the smallest possible active-zone setting. Both SCP-520-1 and SCP-520-2 must only be allowed to affect Foundation assets slated for disposal.-- Testing is currently suspended. See Incident 520-16.

**Description:** SCP-520-1 and SCP-520-2 are large quadruple knife switches constructed from wood, ceramic, and copper. A single unlabeled dial is mounted in SCP-520-2's base and a 48-character LED display is connected across its input contacts with insulated alligator clips.

When connected to an electrical circuit, SCP-520-1 does not function normally to break or complete the circuit to which it is connected. Instead, it splices itself, briefly and remotely, into the primary power circuit of one randomly-selected electrical device within ten meters. Moving the handle from the ON to the OFF position breaks the power circuit, while moving it from OFF to ON completes the circuit, regardless of any other switches or current interruptors. Interruption or completion of the circuit is permanent: wires are physically broken, fuses bypassed, and switches shorted out. The surface of metal connections formed or broken by SCP-520-1 bears signs of extreme oxidation, often to a chemically implausible extent.

SCP-520-2 functions like SCP-520-1, but its targets are selected randomly only from electronic devices inside its active zone that are members of its current selection class. The active zone's current radius is displayed on the left side of the LED display; it may be set to any value between between 5 m and 2,500 km using the dial in the object's base.

The selection class is a subset of electrical devices specified by a brief English phrase (see Addendum 520-6 for examples). The active selection class appears in the center of SCP-520-1's LED display, with a counter of remaining activations on the right. Each class is applied to exactly ten operations before a new one is chosen at random. If there are no members of the selection class inside the active zone, the counter does not decrement until a suitable device can be affected.

Over 680 pages of assorted hard-copy documentation were recovered with SCP-520. They included eight technical papers on anomalous electrical engineering topics; two complete sets of construction diagrams for SCP-520-1, one annotated by hand to roughly resemble SCP-520-2; a set of meticulous step-by-step instructions for building a copy of SCP-520-1, written in the second person and sprinkled with personal and cultural references; and extensive handwritten notes on the process of constructing and modifying an SCP-520 instance.

The retrieved notes end abruptly partway through debugging an attempt to add programmable target-type specificity. Most handwriting in the documentation belongs to PoI-520-B, with occasional notes in PoI-520-A's hand. Many of the notes refer to an ongoing correspondence by phone and e-mail, records of which have not yet been retrieved.

**Addendum 520-1B:** SCP-520-Related Persons of Interest

PoI-520-A is Sylvia Lin, a 23-year-old human female formerly living in Syracuse, NY. She holds a recent B.Eng. in electrical engineering and claims proficiency in electronics manufacture, including certain anomalous techniques. She claims to have built SCP-520-2 with assistance from PoI-520-B, and professes considerable concern for PoI-520-B as a friend and mentor. She is largely cooperative with Foundation requests but remains reluctant to attempt to build new anomalous devices.

PoI-520-B is Ester Pochazka, a 77-year-old human female born in Prague, Czech Republic and formerly living in Utica, NY. She is a retired electrical engineer with an established history of building anomalous electrical devices. She claims to have designed SCP-520-1, written the manuals and diagrams retrieved with the object, and provided the designs and documentation to PoI-520-A as part of a long-distance mentor-student relationship. Since containment, she has expressed no desire to contact PoI-520-A.

Shortly before being contained by the Foundation, PoI-520-B suffered minor ischemic brain damage as a result of pacemaker failure, with symptoms including partial retrograde amnesia. By studying her and PoI-520-A's notes since their containment, she has largely recovered her skills in electrical engineering. However, she claims confusion at the anomalous portions of the SCP-520 documentation, including her own writing, and is sharply skeptical of the basic principles described therein.

**Addendum 520-6:** Sample Selection Classes

The following device selection classes, in reverse chronological order, have been observed since SCP-520 came into Foundation custody.

* FLUORESCENT CEILING LIGHT
* DOORBELL 
* HONDA ACCORD POWER STEERING
* LIBRARY FIRE ALARM
* NEONATAL VENTILATOR
* SYNCHROTRON
* SAFETY CONTROL ROD ACTIVATION MECHANISM
* PACEMAKER

**Incident 520-16:**

On 05/14/2016, researchers conducting routine experiments activated SCP-520-2 eleven times. The first ten activations affected Foundation-owned fluorescent lamps without incident; the tenth activation also changed the selection class to "BOEING 747 AILERON ACTUATOR". Since no aircraft were present in the effect radius, researchers took the opportunity to test SCP-520-2's function in the absence of suitable targets.

When the switch was activated for the eleventh time, however, researchers noted only slight stiffness in the handle. Later examination showed that the force applied to move SCP-520-2's handle was first diverted to adjust its effect-radius selection dial and enlarge the active zone.

Simultaneously, Qantas flight [REDACTED] was lost near Perth with all 532 passengers and crew. Foundation assets embedded with crash investigators successfully retrieved the airplane's relevant hydraulic flight control systems and confirmed all four aileron actuators to have been disabled by SCP-520.

All testing with SCP-520 has been suspended pending development of an alternate method of changing the object's selection class.

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SCP-520

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