Learn Hardcore Korean: eeokeon jeonwon seuwichiga byeoge seolchidwae isseoyo. - The air conditioner’s power switch is installed on the wall.

가/이 marks the grammatical subject and often introduces new or specific information. Here, you’re simply stating where the switch is.
은/는 makes something the topic or adds contrast. 스위치는 벽에… would mean “As for the switch (as opposed to something else), it’s on the wall,” implying contrast or that the listener already knows about the switch.

Why use 에 after 벽 and not 에서?

에 marks a static location (“at/on”), which fits a state like “is installed.”
에서 marks the place where an action occurs. You’d use 에서 with active verbs (e.g., “We worked at the wall”), but with “be installed,” the location is marked by 에: 벽에 설치돼 있어요.

What exactly does 설치돼 있어요 convey?

It’s 설치되다 (to be installed, passive) + -어 있다 (resulting state).
Together, it means “it is in the state of having been installed” (not the act of installing, but the condition that results from it).

How is 설치돼 있어요 different from 설치돼요?

설치돼요 describes an event or general fact (“gets installed,” “is being installed,” “is installed” in a neutral, event-like sense).
설치돼 있어요 focuses on the current state/result (“is installed and remains so”).
Examples:
- 오늘 스위치가 설치돼요. = “The switch is (getting) installed today.”
- 스위치가 설치돼 있어요. = “The switch is installed (it’s there).”

Why is it spelled 돼 and not 되 here?

돼 is the contracted form of 되어 (from 되다
- -어). So 설치되어 있어요 → 설치돼 있어요.
Quick check: if you can expand it to 되어, you should write 돼. Don’t write non-standard forms like 됬어요 (should be 됐어요).

Should it be written 돼 있어요 or 돼있어요?

Standard spacing is separate: 돼 있어요. The pattern -어/아 있다 is written with a space before 있다.
You’ll see 돼있어요 informally, but it’s non-standard.

Could I just say 벽에 있어요 instead of 벽에 설치돼 있어요?

벽에 있어요 only states location (“it’s on the wall”) and doesn’t say it’s an installed fixture.
벽에 설치돼 있어요 adds the nuance that it’s a properly installed/mounted device. Use this when that nuance matters.

Do I need 의 between 에어컨 and 전원 스위치?

No. Stacking nouns is very common: 에어컨 전원 스위치 is natural and concise.
에어컨의 전원 스위치 is also correct, but it can sound a bit more formal or explanatory. Both are fine here.

Can the word order change? For example, can 벽에 move?

Yes. 벽에 에어컨 전원 스위치가 설치돼 있어요 is also fine and puts extra emphasis on the location.
Korean allows some flexibility, but the given order is a neutral, natural default.

What politeness level is -어요 here, and how can I change it?

Can I drop the subject marker 가?

In casual speech, particles like 가/이/은/는 are often omitted when context is clear. You might hear something like: 에어컨 전원 스위치 벽에 설치돼 있어요.
For learners and in careful writing, keep 가 for clarity: 에어컨 전원 스위치가….

Why use the passive 설치되다 instead of the active 설치하다?

The subject is the switch, and you’re describing its state. Passive 설치되다 fits that.
If you focus on the installer’s action, use the active: 에어컨 전원 스위치를 벽에 설치했어요 or …설치해 놨어요 (“installed and left it there”).

How would I talk about time, like past state?

Any quick pronunciation tips?

벽에 sounds like “byeoge” (the ㄱ becomes a softer g before a vowel).
돼 있어요 flows as one phrase: “dwae i-sseo-yo” (many say it quickly like “dwae-sseo-yo”).
Overall: “e-eo-kon jeon-won seu-wi-chi-ga byeoge seol-chi-dwae i-sseo-yo.”

Are there near-synonyms for 설치돼 있다?