when you say its fed from a "gfci and through a switch" does it have a step down xfmr? Is this an existing pool light where your adding another light? Is there a panelboard at the site of the pool equipment(if any)? You should definetly see article 680 of the NEC. At present, more information about the conditions are needed. Pool lighting is dangerous business if not installed correctly. If this is a side job you might want to consider passing on it.
