What kind of grmmar is "ためにと"?

Question

俺以外の奴がいると出ないってことなのか、　あるいは何かあったときのためにと　電気をつけっぱなしでいるのが悪いのか。

Context: The main character told one of his roommates that a ghost has been appearing in his room. So now they are sitting in his room together, but the ghost/weird stuff are not happening.

I understand:

俺以外の奴がいると出ないってことなのか、

Is akin to "one of the possibilities is that it's because there is someone other than me in the room"

あるいは何かあったときのためにと　電気をつけっぱなしでいるのが悪いのか。

However, I'm struggling to parse the second sentence.

電気をつけっぱなしでいるのが悪いのか。

Seem to be "The fault may lie in the fact that the lights are left on"

But then, how is あるいは何かあったときのためにと acting in this sentence?

Particularly I'm stuck with the nuance of ためにと. I think ために is "Because of..." but how is the と here used? I far I understand, the first part "あるいは何かあった" is "Or else something happened".

Answer 1

あるいは何かあったときのためにと　電気をつけっぱなしでいるのが悪いのか。

Your translation of the latter half is correct ("The fault may lie in the fact that the lights are left on" or "maybe the ghost doesn't come out because the lights are left on").

何かあったときのためにと explains why the character has left the lights on. The structure is:

(あるいは (何かあったときのためにと (電気をつけっぱなしでいるのが悪いのか)))

So あるいは affects the whole sentence.

These translation would hopefully help:

電気をつけっぱなしでいるのが悪いのか: The fault may lie in the fact that the lights are left on

何かあったときのためにと 電気をつけっぱなしでいるのが悪いのか: The fault may lie in the fact that the lights are left on, which I have left on in case something happens

あるいは 何かあったときのためにと 電気をつけっぱなしでいるのが悪いのか): Or possibly, the fault may lie in the fact that the lights are left on, which I have left on in case something happens

More literally, XとYいる means something like "I'm in situation Y in the hopes of X". Other examples are: "もっと早く乾けばと、ドライヤーを当てている"、"力になれればと、寄付させていただいている"、"明日も歩けるようにと、休んでいる"