ie wo deru toki ha, denki wo tukeppanasi ni sinaide kudasai.

In this sentence, 家を出る means to leave the house.

Even though を often marks a direct object, with some movement verbs it marks the place that you move away from, pass through, or leave.

So:

• 家を出る = leave the house
• 部屋を出る = leave the room
• 道を歩く = walk along the road
• 公園を通る = go through the park

So here, 家 is not the thing being “done to” in the English sense. It is the place being left.

出る means to go out, to leave, or to exit.

Here it appears in dictionary form because it comes before とき, which often takes:

• the dictionary form if the action is ongoing or still to happen at that time
• the past form if the action is already completed by that time

So:

• 家を出るとき = when you are about to leave / when you leave home
• 家を出たとき = when you had left / when you left and that action was completed

In this sentence, the focus is on the time of leaving, so 出るとき is natural.

とき means time or when.

So:

• 家を出るとき = when leaving the house / when you leave home

The は after it marks that whole time phrase as the topic:

• 家を出るときは、... = As for when you leave the house, ...

This adds a slight sense of general instruction or as for that situation.

Without は, the sentence would still make sense:

• 家を出るとき、電気をつけっぱなしにしないでください。

With は, it sounds a bit more like a rule, reminder, or standard advice.

つけっぱなし means left on.

It comes from:

• つける = to turn on
• 〜っぱなし = left in that state; left as is; done and then not changed

So つけっぱなし means something was turned on and then left on.

Examples:

• テレビをつけっぱなしにする = leave the TV on
• ドアを開けっぱなしにする = leave the door open
• 水を出しっぱなしにする = leave the water running

This pattern is very common in Japanese.

The pattern here is:

• 〜っぱなしにする = to leave something in that state

So:

• 電気をつけっぱなしにする = to leave the lights on

The にする part means to make it into that state or to keep it that way.

So the structure is:

• 電気を = the lights
• つけっぱなしにする = leave on

Then it becomes negative:

• つけっぱなしにしないでください = please do not leave them on

Both are natural, but they are slightly different in focus.

• 消してください = Please turn off the lights.
• つけっぱなしにしないでください = Please do not leave the lights on.

The first tells you the action to do. The second warns against the unwanted state.

So this sentence emphasizes:

• Don’t leave them on when you go out

rather than simply:

• Turn them off

In many real situations, these are almost equivalent, but the nuance is a little different.

Here 電気 means the lights or the electrical lights/appliances being on, depending on context.

Japanese often does not mark singular vs. plural clearly, so 電気 can be understood from context.

In this sentence, the most natural English meaning is:

• the lights

Even though 電気 literally relates to electricity, in everyday usage:

• 電気をつける = turn on the light(s)
• 電気を消す = turn off the light(s)

So this is a very common expression.

Japanese often leaves the subject unstated when it is obvious from context.

Because this sentence ends with ください, it is a request or instruction directed at the listener. So the understood subject is:

• you

So the sentence means something like:

• When you leave the house, please do not leave the lights on.

Not saying あなたは is completely normal. In fact, explicitly saying you would often sound unnecessary.

〜ないでください is a polite and standard way to say please do not do ...

So:

• つけっぱなしにしないでください = Please do not leave it on.

It is polite enough for:

• signs
• notices
• workplace instructions
• speaking respectfully to someone

It is not extremely formal, but it is very normal and appropriate.

Related forms:

• しないで = don’t do it / please don’t do it (less polite, casual)
• しないでくださいませんか = would you please not do it? (more formal / softer)
• しないようにしてください = please make sure not to do it (slightly more indirect)

Yes. A very similar sentence would be:

• 家を出るときは、電気をつけたままにしないでください。

This also means Please don’t leave the lights on when you leave the house.

Difference in nuance:

• つけたまま = left on / remaining on
• つけっぱなし = left on, often with a stronger sense of carelessly or without changing it

So つけっぱなし can sound slightly more critical or more like left on and neglected.

Both are natural, but つけっぱなし is especially common in warnings and reminders.

Japanese often puts information in this order:

1. time or situation
2. object
3. state/action
4. main verb at the end

So this sentence is structured like:

• 家を出るときは = when leaving the house
• 電気を = the lights
• つけっぱなしに = in the state of being left on
• しないでください = please do not do that

A more literal breakdown is:

• As for when you leave the house, please do not make the lights be left on.

That sounds unnatural in English, but it shows how the Japanese grammar is built.

Yes. In this sentence, 家 can naturally be understood as either:

• house
• home

In English, leave home often sounds more natural than leave the house, depending on context.

So both are possible:

• When you leave home, please don’t leave the lights on.
• When you leave the house, please don’t leave the lights on.

The Japanese itself does not strongly force one or the other here.

The sentence is read:

いえ を でる とき は、でんき を つけっぱなし に しないで ください。

More naturally, without the spaces:

いえをでるときは、でんきをつけっぱなしにしないでください。

A few key readings:

• 家 = いえ
• 出る = でる
• 電気 = でんき

It sounds most naturally like a general instruction or habitual reminder:

• Whenever you leave the house, don’t leave the lights on.

That feeling comes from:

• 家を出るとき = when leaving the house
• は = topic marker, often used in general statements
• しないでください = polite request/instruction

So this sounds like something you might see in:

• a notice
• a family reminder
• a workplace rule
• a school instruction