In the US, ATC should not "normally" vector you below the ILS FAF altitude. AIM 5-4-3.c:
The pilot is not expected to turn inbound on the final approach course unless an approach clearance has been issued. This clearance will normally be issued with the final vector for interception of the final approach course, and the vector will be such as to enable the pilot to establish the aircraft on the final approach course prior to reaching the final approach fix.
HOWEVER, it IS allowed per the definition of the FAF in the Pilot/Controller Glossary:
FINAL APPROACH FIX− The fix from which the final approach (IFR) to an airport is executed and which identifies the beginning of the final approach segment. It is designated on Government charts by the Maltese Cross symbol for nonprecision approaches and the lightning bolt symbol for precision approaches; or when ATC directs lower-than-published glideslope/path intercept altitude, it is the resultant actual point of the glideslope/path intercept.