Question : DW & level of normalization

Is 2NF the standard for DW design?
is there any circumstance where 3NF may be applicable?

Answer : DW & level of normalization

it depends 2NF is common, however various parts of the Data warehouse could be in other normalised formats...
 
i seen several cases where a Subject area / schema is in 3NF (typically to support
the ETL  processing and loading of the database)