Learn Hardcore Norwegian: Det er mulig at strømmen er for svak til å skru på ovnen. - It is possible that the power is too weak to turn on the oven.

Det is a dummy subject (an expletive), like English “it” in “It is possible that…”. It doesn’t refer to anything. You can sometimes hear the colloquial shortcut Mulig at strømmen…, but in neutral/standard writing you say Det er mulig at …

Why is the verb er used twice?

There are two clauses, and each clause needs its own verb:

Main clause: Det er mulig …
Subordinate clause (introduced by at): … at strømmen er for svak …

What word order does the at-clause use? Where would I put ikke?

In an at-clause, the order is Subject–Verb–(Adverbs)–Rest:

at strømmen er for svak … If you negate it, ikke comes right after the subject and before the verb:
Det er mulig at strømmen ikke er sterk nok til å skru på ovnen.

Could I say Kanskje instead of Det er mulig at? Does that change word order?

Yes. Det er mulig at strømmen er … ≈ Kanskje (er) strømmen … With kanskje, both orders are used in modern Norwegian:

Kanskje er strømmen for svak …
Kanskje strømmen er for svak … The version with inversion (er in second position) is more formal/written; without inversion is very common in speech.

Why is it svak and not svakt or svake?

Predicative adjectives agree with the subject. Strømmen is masculine singular, so you use svak. Examples:

Lyset (neuter) er svakt.
Lysene (plural) er svake.

What does for mean here?

For means “too” (excessive degree). For svak = “too weak.” It’s not the preposition “for” as in “for someone.”

How does the til å + infinitive part work?

The pattern is: for + adjective + til å + infinitive = “too … to …”

for svak til å skru på = “too weak to turn on” You need til å here; you can’t say for svak å …

Can I rephrase it as “not strong enough to …”?

Yes:

Det er mulig at strømmen ikke er sterk nok til å skru på ovnen. This is equivalent in meaning to for svak til å …, just framed as a negation.

Is for svak strøm different from for lite strøm?

Both are possible but slightly different:

for svak strøm focuses on low strength/voltage/current (quality/intensity).
for lite strøm focuses on quantity/amount (not enough power available). In everyday speech they often overlap.

Skru på, slå på, or sette på—what’s best with ovn?

All can occur, but there are tendencies:

skru på ovnen: very common, especially when there’s a knob/dial (stove/oven/heater).
sette på ovnen: also common (“put the oven on”).
slå på ovnen: usable, but more typical for electronics/switches. Note: skru opp means “turn up/increase,” not “turn on.”

Where does the particle på go with objects and pronouns?

With a noun object, both are fine:

skru på ovnen
skru ovnen på With a pronoun, the pronoun normally goes between verb and particle:
skru den på (not usually skru på den)

What exactly does ovn refer to? Oven, stove, or heater?

Ovn is a general “oven/heater” word. Context decides:

stekeovn: the kitchen oven.
komfyr: the stove unit (often with an oven).
varmeovn: space heater. In a kitchen context, ovnen usually means the oven; in a living room, it could be a heater.

Why are strømmen and ovnen in the definite form?

Norwegian typically uses the definite form for specific, known items in the situation:

strømmen = “the power (supply)”
ovnen = “the (already-known) oven” Use the indefinite form when introducing something new (en ovn), but household fixtures are often treated as known and definite.

Do I need a comma before at in this sentence?

No. Norwegian normally does not use a comma before at introducing a content clause: Det er mulig at … is written without a comma.

Could I say Det kan være at … or Det kan hende at … instead?

Yes, both are natural alternatives:

Det kan være at strømmen er …
Det kan hende at strømmen er … They mean roughly the same as Det er mulig at …, with small nuances of style/register. Muligens and Kanskje are adverb alternatives.