diff --git a/etl/epc/property_change_app.py b/etl/epc/property_change_app.py
index a792ae4a..36eb31b6 100644
--- a/etl/epc/property_change_app.py
+++ b/etl/epc/property_change_app.py
@@ -472,7 +472,9 @@ class EPCRecord:
         """
         Validate a string field
         """
-
+        if not isinstance(field_value, str):
+            raise ValueError(f"Field {record_key} has value {field_value} which is not a string")
+        
         if 'function' in validation_config:
             try:
                 validation_config['function'](field_value)
@@ -487,6 +489,8 @@ class EPCRecord:
         """
         Validate a float field
         """
+        if not isinstance(field_value, float):
+            raise ValueError(f"Field {record_key} has value {field_value} which is not a float")
         
         if 'function' in validation_config:
             try: