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Junction Box

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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 require as much power as the current load (sum) of the ship's powered electrical devices. Junction boxes deteriorate over time while powered, when overloaded with power beyond their overload threshold, when powered and in water, and when on fire. When broken, they can be repaired with a screwdriver. When clicked, the Junction Box presents three lights and two displays, as detailed below.

POWER Display

"How much power is currently being supplied to the electrical grid"

The POWER display on the right provides info on how many kW are received from the Nuclear Reactor. This Power level is the same on all junction boxes. This value is the same as the one found on the Output field on the bottom right of the Reactor.

LOAD display

"How much power is currently being consumed by the devices connected to the electrical grid."

The LOAD display on the right provides info on how many kW the entire subarine electrical system currently needs, including engine activity, pumps and other systems (even those connected to other junction boxes). Note that lights , buttons, buzzers and other small electrical components do not add to the current LOAD of the submarine, nor are they wired to the electrical grid.

Powered Lamp

Shows if the Junction Box is receiving power from the nuclear reactor, and by extension, whether the grid is on. Does not show whether the grid is in a healthy state, only that it is currently operational.

Overvoltage Lamp

When the electrical grid is being supplied more power than what is being consumed, the voltage rises, which may cause damage to electrical devices.

The Overvoltage lamp will light up red if the number in the POWER display is higher than the number in the LOAD display. Besides the obvious waste of fuel that this is, it is also bad due to the deterioration damage all the junction boxes will suffer. The overload threshold for damage on most vanilla Submarine's junction boxes is 1.7. Deterioration from Overvoltage is a problem that must be adressed vigilantly by the crew, as deterioration will eventually lead to the junction boxes catching fire. A few things can be done to mitigate overvoltage, either through skill, upgrades or clever engineering:

  1. As a corner stone of being a capable helmsman, the captain must try to decelerate progressively, by slowly shortening the length of the directional arrow towards the desired position. This will give the reactor time to adjust its power generation.
  2. The crew can buy submarine upgrades to lower the junction box damage from overvoltage.
  3. When manned by a (player-controlled) character, typically an engineer, the the nuclear reactors automatic control can be turned off, and fission rate and turbine output can be set manually, which allows for a faster adjustment. Communication between the captain and the engineer is important as they will need to synchronize properly.
  4. The reactor's automatic control can be made more efficient. Attach certain electrical Wiring Components to the wall next to the reactor and wire their signal_in and signal_out to the reactor. Well thought out automatic reactor controller systems will improve the automatic controls reaction time when adjusting fission rate and turbine output.

Example : The submarine is moving at full speed. The captain suddenly decelerates (by clicking on the submarine or close to it in the nav terminal, resulting in a short or non-existent directional arrow, meaning very little or no engine and/or pumps activity). A reactor on automatic control will lower heat emission as quickly as it can to meet the new power demand, but it takes some time to adjust and while it does, it will still be producing more power than needed. That excess power will cause a Junction Boxes Overvoltage, and the Overvoltage lights will turn on. The Junction Box will deteriorate and eventually fail and catch fire, unless the reactor is able to reduce its heat output to match the level required by the engine activity.

Low Voltage Lamp

when there is not enough power available, the voltage drops, which may cause some devices to shut down The Low Voltage lamp will light up red if the number in the LOAD display is higher than the number in the POWER display.

Example : The submarine is not moving, engine is off, and the reactor is not emitting a lot of heat. The captain suddenly accelerates (by clicking far away from the submarine in the nav terminal, stretching the directional arrow to the maximum, meaning more engine and/or pumps activity). A reactor on automatic control will crank up heat emission as quickly as it can to meet the new power demand. While the reactor struggles to meet the required amount of power, undervoltage happens. This will result in brownouts, where some submarine systems will temporarily cease to function as there is not enough power to go around. The Junction Box Undervoltage light will turn on. It has no other effects, and the brownouts will cease when reactor reaches the total power demand.


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 while powered 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
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.
Outputs the Junction Box's current condition. (0-100)
Outputs the Nuclear Reactor's current Power Output.
Outputs the Ship's current Load.


Submarine Weapons