How I Open Apartment 5 and Solve the First Fuse Box

Quick Answer

The Apartment 5 safe code is 1908.

The radio-shop letter says the shop opened 21 years ago, and the game is set in 1929:

1929 - 21 = 1908

For the floodgate:

go to the radio shop → collect the 4 electrical fuses → return to the Fuse Box → connect wires of the same color → rotate each fuse before placing it → Validate

Once the board validates, power returns and I can open the floodgate toward Miskatonic University.

The first floodgate looks like it should take a minute.

Instead, it sends me through one small loop:

floodgate switchboard

→ Apartment 5

→ radio shop

→ Apartment 5 safe

→ Fuse Box

Once I understand that those rooms belong to the same problem, I stop searching the whole residential building for separate solutions.

Read the Floodgate Note First

I start at the dead switchboard beside the gate.

The clue there gives me the most important direction immediately:

the panel uses radio-shop fuses, and spare fuses are available across the way.

That means I already know where this route is eventually going.

I do not need to search every apartment hoping a random fuse is hidden upstairs.

My destination is the radio shop.

Before I get there, though, Apartment 5 gives me another blocker worth remembering.

Apartment 5 Safe Looks Solvable Before It Actually Is

Inside Apartment 5 I find a wall safe and the note addressed To Martin.

The note implies that the number should be tied to an important moment in Martin’s life.

That tells me the answer means something.

It does not give me enough information to calculate it yet.

The tempting mistake is to start testing whatever numbers are visible in the apartment.

I tried treating the clock as the answer.

It was not.

Once that obvious guess fails, I stop entering random combinations.

The missing information is elsewhere in the same opening route.

Go to the Radio Shop for the Missing Safe Clue

I continue down to the radio shop.

This is the important stop because it solves both unfinished problems:

• the floodgate needs the electrical fuses found here;
• the Apartment 5 safe needs a clue found here.

The letter From A Sister says the shop opened 21 years ago.

The current year is 1929.

So:

1929 - 21 = 1908

Apartment 5 safe code: 1908

That is the number I take back upstairs.

Enter 1908 in the Apartment 5 Safe

I return to Apartment 5 and enter:

1908

The safe opens.

Doing this also unlocks The Inheritance, which is tied to investigating the wall safe.

I prefer finishing it during this same radio-shop loop because I already have the answer and I am still inside the residential building.

There is no reason to carry this four-digit problem into the next district.

Once the safe is done, I turn my attention back to the real progression blocker:

the floodgate.

Pick Up the Four Electrical Fuses in the Radio Shop

The radio shop contains the 4 electrical fuses required for the switchboard.

Once I have them, I do not keep searching the radio shop for another electrical component.

The four fuses are the puzzle pieces.

The next step is to return to the floodgate switchboard.

Fuse Box Rule: Connect Matching Wire Colors

The Fuse Box looks more complicated than its actual rule.

I am not trying to make a symmetrical circuit.

I am not matching the fuses by their physical shape.

The goal is:

connect wires of the same color.

Each fuse acts as a connector between the colored wire segments.

So I trace each color from one side of the board and ask:

Where does this line need to continue?

Then I place the fuse whose connection pattern completes that path.

One of the pieces supports more than a simple straight-line connection, so I pay attention to where the board needs a branch rather than forcing every fuse into a horizontal or vertical line.

Rotate Each Fuse Before Placing It

This is the interaction detail that made the board feel broken the first time.

I placed a fuse, realized it was facing the wrong way, and tried to correct it after placement.

The clean way to solve it is:

select the fuse

→ rotate it first

→ place it

→ check the colored connection

Then I move to the next fuse.

If the layout looks almost correct but the game refuses to accept it, I check orientation before assuming I missed another item.

All four required fuses are already here.

The problem is usually how one of them is facing.

Validate the Fuse Box

When every colored route is connected, I use:

Validate

I wait for the board to accept the arrangement.

That confirmation matters.

A panel that merely looks close is not finished.

Once validation succeeds, power returns to the gate controls.

I activate the floodgate and the route through the water opens.

At that point this opening residential puzzle chain is complete.

What I Finish Before Taking the Boat

Before I leave this area, my checklist is short:

Apartment 5 safe opened with 1908

The Inheritance unlocked

4 electrical fuses collected

matching wire colors connected

Fuse Box validated

floodgate powered and opened

Once all of those are done, I stop searching the residential building.

The next real destination is the Miskatonic Library Annex.

If I am continuing the campaign rather than solving only this opening blocker, I pick up the route from the full The Sinking City 2 walkthrough.