Questions about admitting someone to a psych ward?

This might be quite long but I really need to know these things.

Is it possible to admit a family member to a psych ward? Like, can a sister admit a sibling to a ward or is it only possible for doctors or parents?

Also, if you're suicidal that's a reason they could put you in right? And do they ban electronics like phones or anything?

The reason I'm asking is cause I'm worried my brother isn't safe. He's had quite a lot of suicide attempts and I think I might feel better if I knew he was somewhere safe. I have no idea how any of this works and it would be helpful if someone could tell me about some of it.