Index: trunk/resources/data/validator/relation.mapcss
===================================================================
--- trunk/resources/data/validator/relation.mapcss	(revision 18369)
+++ trunk/resources/data/validator/relation.mapcss	(revision 19467)
@@ -72,2 +72,11 @@
   group: tr("suspicious tag combination");
 }
+
+/* Power relations, #24456 */
+relation[type=power][!power],
+relation[type=power][power][power!~/^(circuit|line_section)$/] {
+       throwError: tr("Power relation misses or combined to wrong power=* value");
+       assertMatch: "relation type=power";
+  assertMatch: "relation type=power power=line";
+       assertNoMatch: "relation type=power power=circuit";
+}