Camondo House - Paris

If you mean the Nissim Camondo museum, allow about 2 hours.

I agree with Norma, 2 hrs is good. I loved the Nissim de Camondo and I recommend it highly.

a heartbreaking family story -- the house is lovely. I who have never cared much for accumulating possessions really really want the set of dinner ware painting with birds on display there.

A couple of hours is enough but there is also a really nice park very close by which may be worth a stop (maybe lunch in the park); it is called Park Monceau (google map it)
I agree with the fact that it is a very sad family history but the home is magnificent - not in a royal Versailles way but in a real lived-in by real (rich) people way.