Learn Hardcore German: Alle Geräte sind vor dem Feierabend auszuschalten. - All devices are to be switched off before the end of the workday.

It’s the sein + zu + infinitive construction. It expresses an instruction/requirement: the devices are to be switched off (i.e., must be switched off). It’s common in written rules and sounds impersonal and formal.

Is this the passive voice?

Not the usual one. The regular passive is werden + Partizip II, e.g., Alle Geräte werden vor dem Feierabend ausgeschaltet (they are being/are switched off). Sein + zu + Infinitiv instead encodes a general rule or necessity, not an ongoing action.

Can I rewrite it with müssen?

Yes: Alle Geräte müssen vor dem Feierabend ausgeschaltet werden. This is functionally equivalent and a bit more direct. Sein + zu + Infinitiv sounds more formal/regulatory.

Why is it auszuschalten with zu in the middle?

Because ausschalten is a separable-prefix verb. With separable verbs, zu goes between the prefix and the stem:

ausschalten → auszuschalten
einkaufen → einzukaufen
abgeben → abzugeben

Why is it vor dem Feierabend (dative)? Which case does vor take here?

Vor is a two-way preposition. With time points or static location, it takes the dative: vor dem Feierabend, vor dem Haus. With movement toward a place, it takes the accusative: Er stellt das Auto vor das Haus. For time, you use the dative.

Can I drop the article and say vor Feierabend?

Yes. With certain temporal nouns, the article is often omitted: vor Feierabend, nach Feierabend, vor Mitternacht. Both vor dem Feierabend and vor Feierabend are fine; the articleless version is very idiomatic.

What’s the difference between vor dem Feierabend and bis (zum) Feierabend?

vor (dem) Feierabend = before that moment; the action happens earlier than the end of the workday.
bis (zum) Feierabend = by/until that time; any time up to that deadline is okay, but not later. In practice, both work in rules, but bis (zum) frames it as a deadline, while vor stresses being earlier than that point.

Why sind and not ist or werden?

The subject Alle Geräte is plural, so the finite verb is sind (3rd person plural). Ist would be singular. Werden would form the passive or future, which is not the construction used here.

Why Geräte and not Gerät or Geräten?

The subject is plural nominative: die Geräte. Singular is das Gerät; plural is die Geräte (with Umlaut + -e). Geräten would be dative plural, which is not needed here.

Does alle need an article here?

No. Alle is used without an article before a plural noun for general reference: alle Geräte. You’d use a determiner only when pointing to a specific set: alle diese Geräte, sometimes alle die Geräte (colloquial, when previously specified).

Can I change the word order?

Yes. Valid options include:

Alle Geräte sind vor dem Feierabend auszuschalten.
Vor dem Feierabend sind alle Geräte auszuschalten. (fronted for emphasis on time) You might hear Alle Geräte sind auszuschalten vor dem Feierabend, but placing the time phrase earlier is more idiomatic.

Could I express this with an imperative?

Yes:

Formal: Schalten Sie alle Geräte vor Feierabend aus.
Informal singular: Schalte alle Geräte vor Feierabend aus.
Informal plural: Schaltet alle Geräte vor Feierabend aus. Imperatives sound more direct; sein + zu + Infinitiv sounds impersonal and rule-like.

Are there synonyms for ausschalten? Any differences?

abschalten: technical/register-neutral, often for machinery or systems.
ausmachen: more colloquial, very common for lights and simple devices.
deaktivieren: disable/deactivate (often software/settings rather than power). All can overlap, but ausschalten is the default for turning devices off.

Does sein + zu + infinitive always mean obligation, or can it mean possibility?

It can express both. In rules and instructions (like here), it implies obligation. With adverbs, it often indicates possibility/difficulty:

Die Geräte sind leicht auszuschalten. (They can be switched off easily.)
Die Geräte sind kaum auszuschalten. (They are hardly switch-off-able.)