A question about electro-shock devices

This is a serious question. Or perhaps a serious set of questions. I'm wondering if someone out there in Blogtopia (a term coined by Skippy) can provide some insight.

Do the staff, or some staff, at psychiatric care facilities have access to disabling devices such as stun-guns, shock wands and stun pencils?

If so, assuming there would be a clear protocol determining the use of such devices, where is the threshold for employment of electrocharged physical disabling devices?

If not, given the touted harmlessness of these devices, is there a reason it is not deployed in facilities where occasional, even rare, events require staff to restrain a patient?

So, if anyone knows the answers, please leave them in "comments". I'm simply curious.

And, I'm not trying to make any point - yet.