diff --git a/google/cloud/bigquery/table.py b/google/cloud/bigquery/table.py
index cbd0d2ee6..8e349cc0e 100644
--- a/google/cloud/bigquery/table.py
+++ b/google/cloud/bigquery/table.py
@@ -2128,9 +2128,11 @@ def to_api_repr(self):
         return self._properties
 
     def _key(self):
+        # because we are only "renaming" top level keys shallow copy is sufficient here.
         properties = self._properties.copy()
         if "type" in properties.keys():
-            properties["type_"] = properties.pop("type")
+            # calling repr for non built-in type objects.
+            properties["type_"] = repr(properties.pop("type"))
         if "requirePartitionFilter" in properties.keys():
             properties["require_partition_filter"] = properties.pop("requirePartitionFilter")
         if "expirationMs" in properties.keys():
@@ -2149,7 +2151,7 @@ def __hash__(self):
         return hash(self._key())
 
     def __repr__(self):
-        key_vals = ["{}={}".format(key, repr(val)) for key, val in self._key()]
+        key_vals = ["{}={}".format(key, val) for key, val in self._key()]
         return "TimePartitioning({})".format(",".join(key_vals))