diff --git a/central_backend/src/devices/device.rs b/central_backend/src/devices/device.rs
index e92870d..150a3e4 100644
--- a/central_backend/src/devices/device.rs
+++ b/central_backend/src/devices/device.rs
@@ -1,7 +1,7 @@
 //! # Devices entities definition
 
 use crate::constants::StaticConstraints;
-use std::collections::HashMap;
+use std::collections::{HashMap, HashSet};
 
 /// Device information provided directly by the device during syncrhonisation.
 ///
@@ -165,7 +165,7 @@ impl DeviceRelay {
             }
         }
 
-        let relays_map = list.iter().map(|r| (r.id, r)).collect::<HashMap<_, _>>();
+        let mut relays_map = list.iter().map(|r| (r.id, r)).collect::<HashMap<_, _>>();
 
         if self.depends_on.iter().any(|d| !relays_map.contains_key(d)) {
             return Some("A specified dependent relay does not exists!");
@@ -179,10 +179,73 @@ impl DeviceRelay {
             return Some("A specified conflicting relay does not exists!");
         }
 
-        // TODO : check for loops
+        // Check for loops in dependencies
+        if self.check_for_loop_in_dependencies(&HashSet::new(), &relays_map) {
+            return Some("A loop was detected in relay dependencies!");
+        }
+
+        // Check if relay is in conflicts with one of its dependencies
+        let mut all_dependencies = HashSet::new();
+        let mut all_conflicts = HashSet::new();
+        self.get_list_of_dependencies_and_conflicts(
+            &mut all_dependencies,
+            &mut all_conflicts,
+            &relays_map,
+        );
+        for conf_id in all_conflicts {
+            if all_dependencies.contains(&conf_id) {
+                return Some(
+                    "The relay or one of its dependencies is in conflict with a dependency!",
+                );
+            }
+        }
 
         None
     }
+
+    fn check_for_loop_in_dependencies(
+        &self,
+        visited: &HashSet<DeviceRelayID>,
+        list: &HashMap<DeviceRelayID, &Self>,
+    ) -> bool {
+        let mut clone = visited.clone();
+        clone.insert(self.id);
+
+        for d in &self.depends_on {
+            if visited.contains(&d) {
+                return true;
+            }
+
+            if list
+                .get(&d)
+                .expect("Missing a relay!")
+                .check_for_loop_in_dependencies(&clone, list)
+            {
+                return true;
+            }
+        }
+
+        false
+    }
+
+    fn get_list_of_dependencies_and_conflicts(
+        &self,
+        deps_out: &mut HashSet<DeviceRelayID>,
+        conflicts_out: &mut HashSet<DeviceRelayID>,
+        list: &HashMap<DeviceRelayID, &Self>,
+    ) {
+        for d in &self.depends_on {
+            let dependency = list.get(&d).expect("Missing a relay!");
+
+            deps_out.insert(dependency.id);
+
+            dependency.get_list_of_dependencies_and_conflicts(deps_out, conflicts_out, list);
+        }
+
+        for d in &self.conflicts_with {
+            conflicts_out.insert(*d);
+        }
+    }
 }
 
 /// Device general information
@@ -213,7 +276,7 @@ impl DeviceGeneralInfo {
 
 #[cfg(test)]
 mod tests {
-    use crate::devices::device::DeviceRelay;
+    use crate::devices::device::{DeviceRelay, DeviceRelayID};
 
     #[test]
     fn check_device_relay_error() {
@@ -238,5 +301,53 @@ mod tests {
         assert!(bad_name.error(&[]).is_some());
         assert_eq!(dep_on_unitary.error(&[unitary.clone()]), None);
         assert!(dep_on_unitary.error(&[]).is_some());
+
+        // Dependency loop
+        let mut dep_cycle_1 = DeviceRelay {
+            id: DeviceRelayID::default(),
+            name: "dep_cycle_1".to_string(),
+            ..Default::default()
+        };
+        let dep_cycle_2 = DeviceRelay {
+            id: DeviceRelayID::default(),
+            name: "dep_cycle_2".to_string(),
+            depends_on: vec![dep_cycle_1.id],
+            ..Default::default()
+        };
+        let dep_cycle_3 = DeviceRelay {
+            id: DeviceRelayID::default(),
+            name: "dep_cycle_3".to_string(),
+            depends_on: vec![dep_cycle_2.id],
+            ..Default::default()
+        };
+        dep_cycle_1.depends_on = vec![dep_cycle_3.id];
+
+        assert!(dep_cycle_1.error(&[dep_cycle_2, dep_cycle_3]).is_some());
+
+        // Impossible conflict
+        let other_dep = DeviceRelay {
+            id: DeviceRelayID::default(),
+            name: "other_dep".to_string(),
+            ..Default::default()
+        };
+        let second_dep = DeviceRelay {
+            id: DeviceRelayID::default(),
+            name: "second_dep".to_string(),
+            conflicts_with: vec![other_dep.id],
+            ..Default::default()
+        };
+        let target_relay = DeviceRelay {
+            id: DeviceRelayID::default(),
+            name: "target_relay".to_string(),
+            depends_on: vec![other_dep.id, second_dep.id],
+            ..Default::default()
+        };
+
+        assert!(target_relay
+            .error(&[other_dep.clone(), second_dep.clone()])
+            .is_some());
+        assert!(target_relay
+            .error(&[other_dep, second_dep, target_relay.clone()])
+            .is_some());
     }
 }
diff --git a/central_backend/src/server/servers.rs b/central_backend/src/server/servers.rs
index 985d412..7e717ec 100644
--- a/central_backend/src/server/servers.rs
+++ b/central_backend/src/server/servers.rs
@@ -165,6 +165,10 @@ pub async fn secure_server(energy_actor: EnergyActorAddr) -> anyhow::Result<()>
                 "/web_api/relays/list",
                 web::get().to(relays_controller::get_list),
             )
+            .route(
+                "/web_api/relays/create",
+                web::post().to(relays_controller::create),
+            )
             // Devices API
             .route(
                 "/devices_api/utils/time",
diff --git a/central_backend/src/server/web_api/relays_controller.rs b/central_backend/src/server/web_api/relays_controller.rs
index 45256f3..8f62978 100644
--- a/central_backend/src/server/web_api/relays_controller.rs
+++ b/central_backend/src/server/web_api/relays_controller.rs
@@ -1,10 +1,23 @@
+use crate::devices::device::{DeviceId, DeviceRelay};
 use crate::energy::energy_actor;
 use crate::server::custom_error::HttpResult;
 use crate::server::WebEnergyActor;
-use actix_web::HttpResponse;
+use actix_web::{web, HttpResponse};
 
 /// Get the full list of relays
 pub async fn get_list(actor: WebEnergyActor) -> HttpResult {
     let list = actor.send(energy_actor::GetRelaysList).await?;
     Ok(HttpResponse::Ok().json(list))
 }
+
+#[derive(serde::Deserialize)]
+pub struct CreateDeviceRelayRequest {
+    device_id: DeviceId,
+    #[serde(flatten)]
+    relay: DeviceRelay,
+}
+
+/// Create a new relay
+pub async fn create(actor: WebEnergyActor, req: web::Json<CreateDeviceRelayRequest>) -> HttpResult {
+    todo!()
+}