Junction Box

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Last updated for version v0.14.6.0
The current game version is v0.17.15.0

Junction Box
Junction Box.png

Category Electrical Installation
Repair Requirements
Electrical Repairs
Electrical Engineering 55
Items Needed Screwdriver

The Junction Box is an installation which serves as a hub for power distribution and relaying signals between devices. For this reason, it is usually a crucial part of the submarine's wiring.


The Junction Box distributes Electricity and Signals through its connected wires. Like all other wireable installations, every pin can have up to five connected wires.

Junction boxes deteriorate over time while powered, when overloaded with power beyond their overload threshold, when powered and in water, and when on fire. The overload threshold for damage on most vanilla Submarine's junction boxes is 1.7.

Overvoltage / Undervoltage

The Junction Boxes require as much power as the current sum of the ships powered electrical devices. If this value of what the systems of the submarine changes rapidly, your junction boxes will either light up with Overvoltage or Undervoltage.

  • Example Undervoltage: Your submarine is not moving, engine iis off. The reactor is not producing a lot of heat. You then give the order on the navigation terminal to maximize speed (click far away from the submarine in the nav terminal, resulting in a long arrow on the nav terminal. A longer arrow, more engine activity). Now, a reactor on automatic control will crank up the reactor heat as quickly as it can to meet this new demand. While the reactor struggles to meet your required amount of power, you will get Undervoltage. This will result in brownouts. Stuff not working, not enough power to go around. The Junction Box Undervoltage light will be lit. It has no other effects, and the brownouts will cease when reactor has reached the threshold required by the engine activity.
  • Example Overvoltage: Your submarine is moving at full speed. You reduce your forward speed to 0 by clicking on the submarine in your nav terminal. (click on the submarine or close to it in the nav terminal, resulting in a short arrow or no arrow on the nav terminal. A shorter arrow, less engine activity). Now, a reactor on automatic control will lower the reactor heat as quickly as it can to meet this new demand. BUT the reactor may take some time to adjust to this. It may still pump out lots of heat. Heat that is now not used by your engine. So the excess heat goes into your wire system and your junction boxes Overvoltage Lights will be lit. The Junction Box will suffer deterioration and will eventually fail and burn, unless the reactor is able to reduce its heat output to match the level required by the engine activity.

Without doing a lot of wiring you can do two easy things to mitigate overvoltage:

  • You can buy submarine upgrades to lower the junction box damage from overvoltage
  • You can avoid going from engine activity = max to engine activity = none. Slowly reduce speed and thus allow your reactor heat to adjust to your changing engine activity.


In order to edit the connections on a junction box, a screwdriver must be equipped in one of the two hand slots, and then the Junction Box Left left-clicked when highlighted. To add a wire to a connection, a wire must be equipped in the other hand, either before or after the Junction Box has been left-clicked.

Damage Values

Unsuccessfully attempting to repair a Junction Box damages the user.

Attack Damage
Kinetic Force
Unsuccessful Repair
Affliction Burn.png Burn : 5

Affliction Stun.png Stun : 5


Junction Boxes take damage while in water, and if they are overvolted beyond their overvolt protection limit:

Cause Damage rate
Submerged in water 0.25/second
Overvolted beyond limit 10.0/second

Connection Panel

Connection panel for Junction Box
Hover over pins to see their descriptions.
Connection Port.png
Connection Port.png
Connection Port.png
Connection Port.png
Connection Port.png
Any devices that are wired to this output will draw their power from the reactor or batteries through the junction box.
Devices wired between this will send signal from one to each other.
Devices wired between this will send signal from one to each other.
Devices wired between this will send signal from one to each other.
Devices wired between this will send signal from one to each other.
Connection Port.png
Outputs the Junction Box's current condition. (0-100)


Submarine Weapons