diff --git a/commons/src/main/java/com/powsybl/dynawo/commons/LoadsMerger.java b/commons/src/main/java/com/powsybl/dynawo/commons/LoadsMerger.java
index 0184fc5e4..46d1a5806 100644
--- a/commons/src/main/java/com/powsybl/dynawo/commons/LoadsMerger.java
+++ b/commons/src/main/java/com/powsybl/dynawo/commons/LoadsMerger.java
@@ -3,12 +3,16 @@
 import com.powsybl.commons.PowsyblException;
 import com.powsybl.iidm.network.*;
 import com.powsybl.iidm.xml.NetworkXml;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
  * @author Dimitri Baudrier <dimitri.baudrier at rte-france.com>
  */
 public class LoadsMerger {
 
+    private static final Logger LOGGER = LoggerFactory.getLogger(LoadsMerger.class);
+
     private static final String MERGE_LOAD_PREFIX_ID = "merged_load_.";
     private final Network initialNetwork;
     private Network mergedLoadsNetwork;
@@ -19,7 +23,9 @@ public LoadsMerger(Network network) {
 
     public Network getMergedLoadsNetwork() {
         if (mergedLoadsNetwork == null) {
+            LOGGER.warn("About to copy network {}", initialNetwork.getId());
             mergedLoadsNetwork = NetworkXml.copy(initialNetwork);
+            LOGGER.warn("Network {} copied", initialNetwork.getId());
         }
         return mergedLoadsNetwork;
     }