How many lamps are in the 7-meter long hallway?

Hello forum,
my house under construction has a hallway with a total length of 7m (length of the living room + stairs upstairs + WC). The electrician planned 2 lights. That seems too few to me.
I intend to illuminate the stairs indirectly through the hallway lighting. Turn on the light downstairs, go upstairs in the light of the hallway, and turn off the light upstairs again.

Edit: the hallway has no windows and is about 150cm wide. The classic narrow hallway.

How many light points should I plan for the hallway?

It's not that simple. It depends on various things:
- area
- height
- desired brightness
- lamp brightness
- lamp beam angle
- reflection behavior of walls and floors
etc.
But two pieces also seem quite few to me. More like 3-5 depending on the points mentioned above.

oh, this is going to get complicated. I don't know anything measurable about the emission behavior of the floor (medium gray tiles) and I also don't know the power of the lamps. I don't even know which lamps will be used yet. 3-5 lamps also seem appropriate to me. With 3 lamps, each lamp has to provide light about 120cm all around, with 5 only about 70cm.

Since you don't know the points, you can only estimate. If you make the lamps dimmable, it will be a bit easier.

I have exactly 4 pieces at 7m. It really bangs at 4000K and a 120°C beam angle.

This is about as helpful as: "My car has standard equipment. I'm always blown away by the six-cylinder engine and automatic transmission."

As rick2018 already wrote:

- Area
- Height
- Desired brightness
- Lamp brightness
- Lamp beam angle
- Emission behavior of walls and floors

Where the emission behavior of the floor has the least influence, since it is usually about 2.5 m away from the light source. What is important, however, is how the walls (and ceilings) look, whether smooth or textured, what color they have, etc.

Example: If I plan four luminaires for 7 x 1.5 = 10.5 m², then at an assumed 100 lux I need about 250 lumens per luminaire (with ideal illumination), which most cheap LEDs can achieve. For public buildings, however, hallways are assumed to have 200 lux (which is already extremely bright at home), but if my luminaires each deliver 1000 lumens, the two planned by the electrician are sufficient, provided we are talking about white walls that help distribute the light evenly. You see, it is an equation with many variables, which fortunately are not unknown.