kaminari ga nattara, pasokon no dengen wo kiru you ni site imasu.

Not necessarily. In Japanese, the conditional pattern 〜たら is made by attaching ら to the plain past form of a verb.

So:

• 鳴る = to sound
• 鳴った = sounded
• 鳴ったら = if / when it sounds

Even though it uses the past form shape, 〜たら often refers to a future condition. The idea is:

• after thunder sounds / if thunder sounds, then...

So the sentence is not mainly about the past. It is setting up a condition: when that happens, this is what I do.

が marks 雷 as the subject of 鳴る.

• 雷が鳴る = thunder sounds / it thunders

Using が is the most neutral way to describe the event itself.

If you said 雷は鳴ったら, it would sound more contrastive or topical, as if you were talking specifically about thunder in contrast with something else. In this sentence, that is usually unnecessary.

So 雷が鳴ったら is the natural choice for when thunder sounds.

Because Japanese expresses this idea differently from English.

• 鳴る means to ring, sound, resound
• 雷が鳴る literally means thunder sounds

English often says it thunders or thunder rumbles, but Japanese naturally treats thunder as the thing making the sound.

This is just a normal collocation:

• ベルが鳴る = the bell rings
• 電話が鳴る = the phone rings
• 雷が鳴る = thunder sounds

It can suggest either, depending on context.

In this sentence, 鳴ったら can be understood as:

• if it thunders
• when thunder sounds

Because thunder is a realistic situation rather than a purely imaginary one, English often translates this kind of sentence more naturally as when.

A useful way to think about 〜たら is:

• first event happens: thunder sounds
• then second event happens: I turn off the computer

So 〜たら often has the feeling of once that happens, then...

Literally, it means:

• パソコン = computer
• の = of
• 電源 = power
• を切る = turn off / cut off

So:

• パソコンの電源を切る = turn off the computer’s power

This is a very standard Japanese way to say turn off the computer.

You may sometimes hear パソコンを切る in casual speech, but it is less precise. The full expression 電源を切る is clearer and more natural in careful Japanese.

〜ようにしている means something like:

• make a point of doing
• try to do
• make it a habit to do
• be careful to do

So:

• 切るようにしています = I make it a point to turn it off
• I try to turn it off
• I make a habit of turning it off

This is stronger than simply saying I turn it off. It suggests a conscious habit or personal rule.

Because the speaker is describing a habit or rule, not just the bare action.

Compare:

• 切っています = I turn it off / I am turning it off / it is off
  
  • depends on context, but it does not strongly express habitual effort
• 切るようにしています = I try to turn it off / I make sure to turn it off

So ようにしています adds the nuance of:

• deliberate practice
• personal routine
• conscious effort

That nuance is very important in this sentence.

Because the verb before ようにする normally appears in its plain dictionary form.

Pattern:

• Verb dictionary form + ようにする
• Verbない-form + ようにする

Examples:

• 早く寝るようにしています = I try to go to bed early
• 甘いものを食べないようにしています = I try not to eat sweets

So 切るようにしています is grammatically normal. The politeness is shown at the end by しています, not by changing 切る into a polite form.

It is about a repeated habit.

The clue is 〜ようにしています, which usually describes an ongoing custom, effort, or routine.

So the sentence means something like:

• whenever thunder sounds, I try to turn off the computer
• I have a habit of turning off the computer when it thunders

If it were about just one occasion, Japanese would probably use a different structure.

It is omitted, which is very common in Japanese.

The sentence does not explicitly say 私は, but the final part 〜しています makes it clear that the speaker is talking about their own habit.

So Japanese often leaves out subjects when they are obvious from context.

A fully explicit version could be:

• 私は、雷が鳴ったら、パソコンの電源を切るようにしています。

But in natural Japanese, leaving out 私は is very normal.

Yes. Even if the meaning has already been given, the nuance of the sentence strongly suggests a practical reason, such as avoiding damage from lightning or power problems.

That is why ようにしています feels especially natural here: it sounds like a safety habit or precaution.

So the sentence is not just reporting an action. It suggests:

• this is something I intentionally do as a precaution