psynursing

Hello, I am a psychiatric nurse that is the only nurse on a team of mental health case managers/clinicians (all of whom have backgrounds in social work). This team treats patients in their homes and goes out to provide mental health support and do a LOT of "social worky" stuff (taking care of finances, transportation, payeeship, housing, funding etc). My job is to take care of the medical/nursing needs - coordinating psychiatrist visits and medications and such. My supervisor (who is also a social worker) wants to train me to 'go on crisis.' This is when a patient is having a mental health crisis after work hours, and needs a crisis assessment at the ER. The clinician doing the crisis then has to find placement for the patient if needed at a mental health facility, and basically be their case manager for the evening. This is basically like being on-call, and whoever is 'on crisis' that day has to go out and do this. My problem is, to be honest, that I really don't want to do this! I have a lot of things going on at home that I don't want to be spending hours on after work if a crisis should happen and I'm on call (plus, the training is all after hours and unpaid). Not only that, as the only nurse I'm kept pretty busy during working hours as it is. So: is this outside the scope of nursing? IS this a social worker's job, not a nurse's? At my previous employment, they had crisis counselors, and none of them were nurses. It seemed the norm for it to be reserved for those with social work backgrounds. Can I rightfully say, "Hey, I don't want to do this, and not only that, I have grounds NOT to based on my profession?" Chime in with your thoughts, please!