diff --git a/Content.Client/Content.Client.csproj b/Content.Client/Content.Client.csproj
index 0c2993fad1..0e49cf09d5 100644
--- a/Content.Client/Content.Client.csproj
+++ b/Content.Client/Content.Client.csproj
@@ -70,6 +70,7 @@
   <ItemGroup>
     <Compile Include="EntryPoint.cs" />
     <Compile Include="GameObjects\Components\Inventory\ClientInventoryComponent.cs" />
+    <Compile Include="GameObjects\Components\Power\ApcBoundUserInterface.cs" />
     <Compile Include="GameObjects\Components\Storage\ClientStorageComponent.cs" />
     <Compile Include="Input\ContentContexts.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
diff --git a/Content.Client/GameObjects/Components/Power/ApcBoundUserInterface.cs b/Content.Client/GameObjects/Components/Power/ApcBoundUserInterface.cs
new file mode 100644
index 0000000000..9307b50b26
--- /dev/null
+++ b/Content.Client/GameObjects/Components/Power/ApcBoundUserInterface.cs
@@ -0,0 +1,75 @@
+using System;
+using Content.Shared.GameObjects.Components.Power;
+using SS14.Client.GameObjects.Components.UserInterface;
+using SS14.Client.UserInterface.Controls;
+using SS14.Client.UserInterface.CustomControls;
+using SS14.Shared.GameObjects.Components.UserInterface;
+using SS14.Shared.Utility;
+
+namespace Content.Client.GameObjects.Components.Power
+{
+    public class ApcBoundUserInterface : BoundUserInterface
+    {
+        private SS14Window _window;
+        private BaseButton _breakerButton;
+        private Label _externalPowerStateLabel;
+        private ProgressBar _chargeBar;
+
+        protected override void Open()
+        {
+            base.Open();
+
+            _window = new ApcWindow();
+            _window.OnClose += Close;
+            _breakerButton = _window.Contents.GetChild<BaseButton>("Rows/Breaker/Breaker");
+            _breakerButton.OnPressed += _ => SendMessage(new ApcToggleMainBreakerMessage());
+            _externalPowerStateLabel = _window.Contents.GetChild<Label>("Rows/ExternalStatus/Status");
+            _chargeBar = _window.Contents.GetChild<ProgressBar>("Rows/Charge/Charge");
+            _window.AddToScreen();
+        }
+
+        public ApcBoundUserInterface(ClientUserInterfaceComponent owner, object uiKey) : base(owner, uiKey)
+        {
+        }
+
+        protected override void UpdateState(BoundUserInterfaceState state)
+        {
+            base.UpdateState(state);
+
+            var castState = (ApcBoundInterfaceState) state;
+
+            _breakerButton.Pressed = castState.MainBreaker;
+            switch (castState.ApcExternalPower)
+            {
+                case ApcExternalPowerState.None:
+                    _externalPowerStateLabel.Text = "None";
+                    break;
+                case ApcExternalPowerState.Low:
+                    _externalPowerStateLabel.Text = "Low";
+                    break;
+                case ApcExternalPowerState.Good:
+                    _externalPowerStateLabel.Text = "Good";
+                    break;
+                default:
+                    throw new ArgumentOutOfRangeException();
+            }
+
+            _chargeBar.Value = castState.Charge;
+        }
+
+        protected override void Dispose(bool disposing)
+        {
+            base.Dispose(disposing);
+
+            if (disposing)
+            {
+                _window.Dispose();
+            }
+        }
+
+        private class ApcWindow : SS14Window
+        {
+            protected override ResourcePath ScenePath => new ResourcePath("/Scenes/Power/Apc.tscn");
+        }
+    }
+}
diff --git a/Content.Server/GameObjects/Components/Power/ApcComponent.cs b/Content.Server/GameObjects/Components/Power/ApcComponent.cs
index c68ed7f4e4..415ea9bce8 100644
--- a/Content.Server/GameObjects/Components/Power/ApcComponent.cs
+++ b/Content.Server/GameObjects/Components/Power/ApcComponent.cs
@@ -1,23 +1,42 @@
-using Content.Shared.GameObjects.Components.Power;
+using Content.Server.GameObjects.EntitySystems;
+using Content.Shared.GameObjects.Components.Power;
 using SS14.Server.GameObjects;
-using SS14.Shared.GameObjects;
+using SS14.Server.GameObjects.Components.UserInterface;
+using SS14.Server.Interfaces.GameObjects;
+using SS14.Shared.GameObjects.Components.UserInterface;
+using SS14.Shared.Interfaces.GameObjects;
 
 namespace Content.Server.GameObjects.Components.Power
 {
-    public class ApcComponent : Component
+    public sealed class ApcComponent : SharedApcComponent, IAttackHand
     {
-        public override string Name => "Apc";
-
         PowerStorageComponent Storage;
         AppearanceComponent Appearance;
+        private PowerProviderComponent _provider;
 
         ApcChargeState LastChargeState;
+        private float _lastCharge = 0f;
+        private ApcExternalPowerState _lastExternalPowerState;
+        private BoundUserInterface _userInterface;
+        private bool _uiDirty = true;
 
         public override void Initialize()
         {
             base.Initialize();
             Storage = Owner.GetComponent<PowerStorageComponent>();
             Appearance = Owner.GetComponent<AppearanceComponent>();
+            _provider = Owner.GetComponent<PowerProviderComponent>();
+            _userInterface = Owner.GetComponent<ServerUserInterfaceComponent>().GetBoundUserInterface(ApcUiKey.Key);
+            _userInterface.OnReceiveMessage += UserInterfaceOnOnReceiveMessage;
+        }
+
+        private void UserInterfaceOnOnReceiveMessage(BoundUserInterfaceMessage obj)
+        {
+            if (obj is ApcToggleMainBreakerMessage)
+            {
+                _provider.MainBreaker = !_provider.MainBreaker;
+                _uiDirty = true;
+            }
         }
 
         public void OnUpdate()
@@ -28,23 +47,68 @@ namespace Content.Server.GameObjects.Components.Power
                 LastChargeState = newState;
                 Appearance.SetData(ApcVisuals.ChargeState, newState);
             }
+
+            var newCharge = Storage.Charge;
+            if (newCharge != _lastCharge)
+            {
+                _lastCharge = newCharge;
+                _uiDirty = true;
+            }
+
+            var extPowerState = CalcExtPowerState();
+            if (extPowerState != _lastExternalPowerState)
+            {
+                _lastExternalPowerState = extPowerState;
+                _uiDirty = true;
+            }
+
+            if (_uiDirty)
+            {
+                _userInterface.SetState(new ApcBoundInterfaceState(_provider.MainBreaker, extPowerState, newCharge / Storage.Capacity));
+                _uiDirty = false;
+            }
         }
 
-        ApcChargeState CalcChargeState()
+        private ApcChargeState CalcChargeState()
         {
             var storageCharge = Storage.GetChargeState();
-            if (storageCharge == ChargeState.Discharging)
+            switch (storageCharge)
             {
-                return ApcChargeState.Lack;
+                case ChargeState.Discharging:
+                    return ApcChargeState.Lack;
+                case ChargeState.Charging:
+                    return ApcChargeState.Charging;
+                default:
+                    // Still.
+                    return Storage.Full ? ApcChargeState.Full : ApcChargeState.Lack;
+            }
+        }
+
+        private ApcExternalPowerState CalcExtPowerState()
+        {
+            if (!Owner.TryGetComponent(out PowerNodeComponent node) || node.Parent == null)
+            {
+                return ApcExternalPowerState.None;
             }
 
-            if (storageCharge == ChargeState.Charging)
+            var net = node.Parent;
+            if (net.LastTotalAvailable <= 0)
             {
-                return ApcChargeState.Charging;
+                return ApcExternalPowerState.None;
             }
 
-            // Still.
-            return Storage.Full ? ApcChargeState.Full : ApcChargeState.Lack;
+            return net.Lack > 0 ? ApcExternalPowerState.Low : ApcExternalPowerState.Good;
+        }
+
+        bool IAttackHand.Attackhand(IEntity user)
+        {
+            if (!user.TryGetComponent(out IActorComponent actor))
+            {
+                return false;
+            }
+
+            _userInterface.Open(actor.playerSession);
+            return true;
         }
     }
 }
diff --git a/Content.Server/GameObjects/Components/Power/PowerDebugTool.cs b/Content.Server/GameObjects/Components/Power/PowerDebugTool.cs
index 151a11f844..2b3f238c5c 100644
--- a/Content.Server/GameObjects/Components/Power/PowerDebugTool.cs
+++ b/Content.Server/GameObjects/Components/Power/PowerDebugTool.cs
@@ -3,7 +3,6 @@ using System.Text;
 using Content.Server.GameObjects.EntitySystems;
 using Content.Shared.GameObjects.Components.Power;
 using SS14.Server.Interfaces.GameObjects;
-using SS14.Shared.GameObjects;
 using SS14.Shared.Interfaces.GameObjects;
 using SS14.Shared.Interfaces.GameObjects.Components;
 using SS14.Shared.Map;
@@ -32,7 +31,22 @@ namespace Content.Server.GameObjects.Components.Power
                 }
                 else
                 {
-                    builder.AppendFormat("  Powernet: {0}\n", node.Parent.Uid);
+                    var net = node.Parent;
+                    builder.AppendFormat(@"  Powernet: {0}
+  Wires: {1}, Nodes: {2}
+  Generators: {3}, Loaders: {4},
+  StorageS: {5}, StorageC: {6},
+  Load: {7}, Supply: {8},
+  LAvail: {9}, LDraw: {10},
+  LDemand: {11}, LDemandWS: {12},
+",
+                        net.Uid,
+                        net.NodeList.Count, net.WireList.Count,
+                        net.GeneratorCount, net.DeviceCount,
+                        net.PowerStorageSupplierCount, net.PowerStorageConsumerCount,
+                        net.Load, net.Supply,
+                        net.LastTotalAvailable, net.LastTotalDraw,
+                        net.LastTotalDemand, net.LastTotalDemandWithSuppliers);
                 }
             }
 
diff --git a/Content.Server/GameObjects/Components/Power/PowerProviderComponent.cs b/Content.Server/GameObjects/Components/Power/PowerProviderComponent.cs
index 575e59f361..f6209f5480 100644
--- a/Content.Server/GameObjects/Components/Power/PowerProviderComponent.cs
+++ b/Content.Server/GameObjects/Components/Power/PowerProviderComponent.cs
@@ -31,12 +31,14 @@ namespace Content.Server.GameObjects.Components.Power
             get => _range;
             private set => _range = value;
         }
+
         private int _range = 0;
 
         /// <summary>
         /// List storing all the power devices that we are currently providing power to
         /// </summary>
-        public SortedSet<PowerDeviceComponent> DeviceLoadList = new SortedSet<PowerDeviceComponent>(new Powernet.DevicePriorityCompare());
+        public SortedSet<PowerDeviceComponent> DeviceLoadList =
+            new SortedSet<PowerDeviceComponent>(new Powernet.DevicePriorityCompare());
 
         /// <summary>
         ///     List of devices in range that we "advertised" to.
@@ -47,6 +49,46 @@ namespace Content.Server.GameObjects.Components.Power
 
         public override Powernet.Priority Priority { get; protected set; } = Powernet.Priority.Provider;
 
+        private bool _mainBreaker = true;
+
+        public bool MainBreaker
+        {
+            get => _mainBreaker;
+            set
+            {
+                if (_mainBreaker == value)
+                {
+                    return;
+                }
+
+                _mainBreaker = value;
+                if (!value)
+                {
+                    DepowerAllDevices();
+                    Load = 0;
+                }
+                else
+                {
+                    Load = TheoreticalLoad;
+                }
+            }
+        }
+
+        private float _theoreticalLoad = 0f;
+
+        public float TheoreticalLoad
+        {
+            get => _theoreticalLoad;
+            set
+            {
+                _theoreticalLoad = value;
+                if (MainBreaker)
+                {
+                    Load = value;
+                }
+            }
+        }
+
         public PowerProviderComponent()
         {
             Load = 0;
@@ -60,6 +102,7 @@ namespace Content.Server.GameObjects.Components.Power
             {
                 device.RemoveProvider(this);
             }
+
             AdvertisedDevices.Clear();
         }
 
@@ -79,17 +122,21 @@ namespace Content.Server.GameObjects.Components.Power
                 return;
             }
 
+            if (!MainBreaker)
+            {
+                return;
+            }
+
             if (ExternalPowered)
             {
                 PowerAllDevices();
                 return;
             }
 
-
-            if (storage.CanDeductCharge(Load * frametime))
+            if (storage.CanDeductCharge(TheoreticalLoad * frametime))
             {
                 PowerAllDevices();
-                storage.DeductCharge(Load * frametime);
+                storage.DeductCharge(TheoreticalLoad * frametime);
                 return;
             }
 
@@ -110,6 +157,7 @@ namespace Content.Server.GameObjects.Components.Power
                         DepoweredDevices.Remove(device);
                         device.ExternalPowered = true;
                     }
+
                     usedEnergy += deviceLoad;
                     remainingEnergy -= deviceLoad;
                 }
@@ -117,12 +165,14 @@ namespace Content.Server.GameObjects.Components.Power
 
             storage.DeductCharge(usedEnergy);
         }
+
         private void PowerAllDevices()
         {
             foreach (var device in DepoweredDevices)
             {
                 device.ExternalPowered = true;
             }
+
             DepoweredDevices.Clear();
         }
 
@@ -131,6 +181,7 @@ namespace Content.Server.GameObjects.Components.Power
             foreach (var device in DeviceLoadList)
             {
                 device.ExternalPowered = false;
+                DepoweredDevices.Add(device);
             }
         }
 
@@ -142,7 +193,7 @@ namespace Content.Server.GameObjects.Components.Power
             var _emanager = IoCManager.Resolve<IServerEntityManager>();
             var position = Owner.GetComponent<ITransformComponent>().WorldPosition;
             var entities = _emanager.GetEntitiesInRange(Owner, PowerRange)
-                        .Where(x => x.HasComponent<PowerDeviceComponent>());
+                .Where(x => x.HasComponent<PowerDeviceComponent>());
 
 
             foreach (var entity in entities)
@@ -171,6 +222,7 @@ namespace Content.Server.GameObjects.Components.Power
             {
                 device.RemoveProvider(this);
             }
+
             AdvertisedDevices.Clear();
         }
 
@@ -180,7 +232,7 @@ namespace Content.Server.GameObjects.Components.Power
         public void AddDevice(PowerDeviceComponent device)
         {
             DeviceLoadList.Add(device);
-            Load += device.Load;
+            TheoreticalLoad += device.Load;
             if (!device.Powered)
                 DepoweredDevices.Add(device);
         }
@@ -192,8 +244,8 @@ namespace Content.Server.GameObjects.Components.Power
         {
             if (DeviceLoadList.Contains(device))
             {
-                Load -= oldLoad;
-                Load += device.Load;
+                TheoreticalLoad -= oldLoad;
+                TheoreticalLoad += device.Load;
             }
         }
 
@@ -204,14 +256,15 @@ namespace Content.Server.GameObjects.Components.Power
         {
             if (DeviceLoadList.Contains(device))
             {
-                Load -= device.Load;
+                TheoreticalLoad -= device.Load;
                 DeviceLoadList.Remove(device);
                 if (DepoweredDevices.Contains(device))
                     DepoweredDevices.Remove(device);
             }
             else
             {
-                Logger.WarningS("power", "We tried to remove device {0} twice from the same {1}, somehow.", device.Owner, Owner);
+                Logger.WarningS("power", "We tried to remove device {0} twice from the same {1}, somehow.",
+                    device.Owner, Owner);
             }
         }
     }
diff --git a/Content.Server/GameObjects/Components/Power/Powernet.cs b/Content.Server/GameObjects/Components/Power/Powernet.cs
index 2750d4d751..5bea80adc9 100644
--- a/Content.Server/GameObjects/Components/Power/Powernet.cs
+++ b/Content.Server/GameObjects/Components/Power/Powernet.cs
@@ -8,7 +8,7 @@ using System.Collections.Generic;
 namespace Content.Server.GameObjects.Components.Power
 {
     /// <summary>
-    /// Master class for group of powertransfercomponents, takes in and distributes power via nodes
+    /// Master class for group of <see cref="PowerTransferComponent"/>, takes in and distributes power via nodes
     /// </summary>
     public class Powernet
     {
@@ -38,12 +38,18 @@ namespace Content.Server.GameObjects.Components.Power
         /// <summary>
         ///     Subset of nodelist that adds a continuous power supply to the network
         /// </summary>
-        private readonly Dictionary<PowerGeneratorComponent, float> GeneratorList = new Dictionary<PowerGeneratorComponent, float>();
+        private readonly Dictionary<PowerGeneratorComponent, float> GeneratorList =
+            new Dictionary<PowerGeneratorComponent, float>();
+
+        public int GeneratorCount => GeneratorList.Count;
 
         /// <summary>
         ///     Subset of nodelist that draw power, stores information on current continuous powernet load
         /// </summary>
-        private readonly SortedSet<PowerDeviceComponent> DeviceLoadList = new SortedSet<PowerDeviceComponent>(new DevicePriorityCompare());
+        private readonly SortedSet<PowerDeviceComponent> DeviceLoadList =
+            new SortedSet<PowerDeviceComponent>(new DevicePriorityCompare());
+
+        public int DeviceCount => DeviceLoadList.Count;
 
         /// <summary>
         ///     All the devices that have been depowered by this powernet or depowered prior to being absorted into this powernet
@@ -55,11 +61,15 @@ namespace Content.Server.GameObjects.Components.Power
         /// </summary>
         private readonly List<PowerStorageComponent> PowerStorageSupplierList = new List<PowerStorageComponent>();
 
+        public int PowerStorageSupplierCount => PowerStorageSupplierList.Count;
+
         /// <summary>
         ///     A list of energy storage components that will never feed the powernet, will try to draw energy to feed themselves if possible
         /// </summary>
         private readonly List<PowerStorageComponent> PowerStorageConsumerList = new List<PowerStorageComponent>();
 
+        public int PowerStorageConsumerCount => PowerStorageConsumerList.Count;
+
         /// <summary>
         ///     Static counter of all continuous load placed from devices on this power network.
         ///     In Watts.
@@ -67,7 +77,7 @@ namespace Content.Server.GameObjects.Components.Power
         public float Load { get; private set; } = 0;
 
         /// <summary>
-        ///     Static counter of all continiuous supply from generators on this power network.
+        ///     Static counter of all continuous supply from generators on this power network.
         ///     In Watts.
         /// </summary>
         public float Supply { get; private set; } = 0;
@@ -77,47 +87,108 @@ namespace Content.Server.GameObjects.Components.Power
         /// </summary>
         public bool Dirty { get; set; } = false;
 
+        // These are stats for power monitoring equipment such as APCs.
+
+        /// <summary>
+        ///     The total supply that was available to us last tick.
+        ///     This does not mean it was used.
+        /// </summary>
+        public float LastTotalAvailable { get; private set; }
+
+        /// <summary>
+        ///     The total power drawn last tick.
+        ///     This is how much power was actually, in practice, drawn.
+        ///     Not how much SHOULD have been drawn.
+        ///     If avail &lt; demand, this will be just &lt;= than the actual avail
+        ///     (e.g. if all machines need 100 W but there's 20 W excess, the 20 W will be avail but not drawn.)
+        /// </summary>
+        public float LastTotalDraw { get; private set; }
+
+        /// <summary>
+        ///     The amount of power that was demanded last tick.
+        ///     This does not mean it was full filled in practice.
+        ///     This does not include the demand from storage suppliers until the suppliers are actually capable of drawing power.
+        ///     As such, this will quite abruptly shoot up if available rises to cover supplier charge demand too.
+        /// </summary>
+        /// <seealso cref="LastTotalDemandWithSuppliers"/>
+        public float LastTotalDemand { get; private set; }
+
+        /// <summary>
+        ///     The amount of power that was demanded last tick, ALWAYS including storage supplier draw.
+        ///     This does not mean it was full filled in practice.
+        ///     See <see cref="LastTotalDemand"/> for the difference.
+        /// </summary>
+        public float LastTotalDemandWithSuppliers { get; private set; }
+
+        /// <summary>
+        ///     The amount of power that we are lacking to properly power everything (excluding storage supplier charging).
+        /// </summary>
+        public float Lack => Math.Max(0, LastTotalDemand - LastTotalAvailable);
+
+        /// <summary>
+        ///     The total amount of power that wasn't used last tick.
+        ///     This does not necessarily mean it went to waste, unused supply from storage is also counted.
+        ///     It is ALSO not implied that if this is &gt; 0, that we have sufficient power for everything.
+        ///     See the doc comment on <see cref="LastTotalDraw"/>.
+        /// </summary>
+        public float Excess => Math.Max(0, LastTotalAvailable - LastTotalDraw);
+
         public void Update(float frameTime)
         {
-            float activesupply = Supply * frameTime;
-            float activeload = Load * frameTime;
-
-            float storageconsumerdemand = 0;
+            // The amount of energy that is supplied from generators that do not care if it's used or not.
+            var activeSupply = Supply * frameTime;
+            // The total load we need to fill for machines.
+            var activeLoad = Load * frameTime;
 
+            // The total load from storage consumers (batteries that do not supply like an SMES)
+            float storageConsumerDemand = 0;
             foreach (var supply in PowerStorageConsumerList)
             {
-                storageconsumerdemand += supply.RequestCharge(frameTime);
+                storageConsumerDemand += supply.RequestCharge(frameTime);
             }
 
-            float storagesupply = 0;
-            float storagesupplierdemand = 0;
-
+            // The total supply from storage suppliers.
+            float storageSupply = 0;
+            // The total load from storage suppliers (batteries that DO supply like an SMES)
+            float storageSupplierDemand = 0;
             foreach (var supply in PowerStorageSupplierList)
             {
-                storagesupply += supply.AvailableCharge(frameTime);
-                storagesupplierdemand += supply.RequestCharge(frameTime);
+                storageSupply += supply.AvailableCharge(frameTime);
+                storageSupplierDemand += supply.RequestCharge(frameTime);
             }
 
+            LastTotalAvailable = (storageSupply + activeSupply) / frameTime;
+            LastTotalDemandWithSuppliers = (activeLoad + storageConsumerDemand + storageSupplierDemand) / frameTime;
 
-            //If we have enough power to feed all load and storage demand, then feed everything
-            if (activesupply > activeload + storageconsumerdemand + storagesupplierdemand)
+            // The happy case.
+            // If we have enough power to feed all load and storage demand, then feed everything
+            if (activeSupply > activeLoad + storageConsumerDemand + storageSupplierDemand)
             {
                 PowerAllDevices();
                 ChargeStorageConsumers(frameTime);
                 ChargeStorageSuppliers(frameTime);
+                LastTotalDraw = LastTotalDemand = LastTotalDemandWithSuppliers;
                 return;
             }
-            //We don't have enough power for the storage powernet suppliers, ignore powering them
-            else if (activesupply > activeload + storageconsumerdemand)
+
+            LastTotalDemand = (activeLoad + storageConsumerDemand) / frameTime;
+
+            // We don't have enough power for the storage powernet suppliers, ignore powering them
+            // TODO: This is technically incorrect, it's totally possible to power *some* suppliers here,
+            // just not all.
+            if (activeSupply > activeLoad + storageConsumerDemand)
             {
                 PowerAllDevices();
                 ChargeStorageConsumers(frameTime);
+                LastTotalDraw = LastTotalDemand;
                 return;
             }
 
+            // The complex case: There is too little power to power everything without using storage suppliers (SMES).
+            // We have to keep track of power draw as to not incorrectly detract too much from storage suppliers.
 
-            float totalRemaining = activesupply + storagesupply;
-
+            // Calculate the total potential supply, then go through every normal load and detract.
+            var totalRemaining = activeSupply + storageSupply;
             foreach (var device in DeviceLoadList)
             {
                 var deviceLoad = device.Load * frameTime;
@@ -137,25 +208,35 @@ namespace Content.Server.GameObjects.Components.Power
                 }
             }
 
-            // What we have left goes into storage consumers.
-            foreach (var consumer in PowerStorageConsumerList)
+            if (totalRemaining > 0)
             {
-                if (totalRemaining < 0)
+                // What we have left (if any) goes into storage consumers.
+                foreach (var consumer in PowerStorageConsumerList)
                 {
-                    break;
+                    if (totalRemaining < 0)
+                    {
+                        break;
+                    }
+
+                    var demand = consumer.RequestCharge(frameTime);
+                    if (demand == 0)
+                    {
+                        continue;
+                    }
+
+                    var taken = Math.Min(demand, totalRemaining);
+                    totalRemaining -= taken;
+                    consumer.AddCharge(taken);
                 }
-                var demand = consumer.RequestCharge(frameTime);
-                if (demand == 0)
-                {
-                    continue;
-                }
-                var taken = Math.Min(demand, totalRemaining);
-                totalRemaining -= taken;
-                consumer.AddCharge(taken);
             }
 
-            var supplierUsed = storagesupply - totalRemaining;
+            LastTotalDraw = (activeSupply + storageSupply - totalRemaining) / frameTime;
 
+            // activeSupply is free to use, but storageSupply is not.
+            // Calculate how much of storageSupply, and deduct it from the storage suppliers.
+            var supplierUsed = storageSupply - totalRemaining;
+
+            // And deduct!
             foreach (var supplier in PowerStorageSupplierList)
             {
                 var load = supplier.AvailableCharge(frameTime);
@@ -163,6 +244,7 @@ namespace Content.Server.GameObjects.Components.Power
                 {
                     continue;
                 }
+
                 var added = Math.Min(load, supplierUsed);
                 supplierUsed -= added;
                 supplier.DeductCharge(added);
@@ -179,6 +261,7 @@ namespace Content.Server.GameObjects.Components.Power
             {
                 device.ExternalPowered = true;
             }
+
             DepoweredDevices.Clear();
         }
 
@@ -208,6 +291,7 @@ namespace Content.Server.GameObjects.Components.Power
             {
                 NodeList[0].DisconnectFromPowernet();
             }
+
             GeneratorList.Clear();
             DeviceLoadList.Clear();
             DepoweredDevices.Clear();
@@ -228,6 +312,7 @@ namespace Content.Server.GameObjects.Components.Power
             {
                 wire.Parent = this;
             }
+
             WireList.AddRange(toMerge.WireList);
             toMerge.WireList.Clear();
 
@@ -235,6 +320,7 @@ namespace Content.Server.GameObjects.Components.Power
             {
                 node.Parent = this;
             }
+
             NodeList.AddRange(toMerge.NodeList);
             toMerge.NodeList.Clear();
 
@@ -242,6 +328,7 @@ namespace Content.Server.GameObjects.Components.Power
             {
                 GeneratorList.Add(generator.Key, generator.Value);
             }
+
             Supply += toMerge.Supply;
             toMerge.Supply = 0;
             toMerge.GeneratorList.Clear();
@@ -250,6 +337,7 @@ namespace Content.Server.GameObjects.Components.Power
             {
                 DeviceLoadList.Add(device);
             }
+
             Load += toMerge.Load;
             toMerge.Load = 0;
             toMerge.DeviceLoadList.Clear();
@@ -362,7 +450,8 @@ namespace Content.Server.GameObjects.Components.Power
             }
             else
             {
-                Logger.WarningS("power", "We tried to remove generator {0} twice from {1}, somehow.", generator.Owner, this);
+                Logger.WarningS("power", "We tried to remove generator {0} twice from {1}, somehow.", generator.Owner,
+                    this);
             }
         }
 
@@ -402,11 +491,13 @@ namespace Content.Server.GameObjects.Components.Power
             {
                 PowerStorageSupplierList.Remove(storage);
             }
+
             if (PowerStorageConsumerList.Contains(storage))
             {
                 PowerStorageSupplierList.Remove(storage);
             }
         }
+
         #endregion Registration
 
         public override string ToString()
@@ -441,6 +532,7 @@ namespace Content.Server.GameObjects.Components.Power
                 {
                     return y.Owner.Uid.CompareTo(x.Owner.Uid);
                 }
+
                 return compare;
             }
         }
diff --git a/Content.Shared/GameObjects/Components/Power/SharedApcComponent.cs b/Content.Shared/GameObjects/Components/Power/SharedApcComponent.cs
index 5ff2c23114..c97b8a674b 100644
--- a/Content.Shared/GameObjects/Components/Power/SharedApcComponent.cs
+++ b/Content.Shared/GameObjects/Components/Power/SharedApcComponent.cs
@@ -1,8 +1,15 @@
 using System;
+using SS14.Shared.GameObjects;
+using SS14.Shared.GameObjects.Components.UserInterface;
 using SS14.Shared.Serialization;
 
 namespace Content.Shared.GameObjects.Components.Power
 {
+    public abstract class SharedApcComponent : Component
+    {
+        public sealed override string Name => "Apc";
+    }
+
     [Serializable, NetSerializable]
     public enum ApcVisuals
     {
@@ -27,4 +34,37 @@ namespace Content.Shared.GameObjects.Components.Power
         /// </summary>
         Full,
     }
+
+    [Serializable, NetSerializable]
+    public sealed class ApcBoundInterfaceState : BoundUserInterfaceState
+    {
+        public readonly bool MainBreaker;
+        public readonly ApcExternalPowerState ApcExternalPower;
+        public readonly float Charge;
+
+        public ApcBoundInterfaceState(bool mainBreaker, ApcExternalPowerState apcExternalPower, float charge)
+        {
+            MainBreaker = mainBreaker;
+            ApcExternalPower = apcExternalPower;
+            Charge = charge;
+        }
+    }
+
+    [Serializable, NetSerializable]
+    public sealed class ApcToggleMainBreakerMessage : BoundUserInterfaceMessage
+    {
+    }
+
+    public enum ApcExternalPowerState
+    {
+        None,
+        Low,
+        Good,
+    }
+
+    [NetSerializable, Serializable]
+    public enum ApcUiKey
+    {
+        Key,
+    }
 }
diff --git a/Resources/Prototypes/Entities/Power.yml b/Resources/Prototypes/Entities/Power.yml
index cc91c136b4..36dff57b20 100644
--- a/Resources/Prototypes/Entities/Power.yml
+++ b/Resources/Prototypes/Entities/Power.yml
@@ -81,6 +81,10 @@
   - type: Appearance
     visuals:
     - type: ApcVisualizer2D
+  - type: UserInterface
+    interfaces:
+    - key: enum.ApcUiKey.Key
+      type: ApcBoundUserInterface
 
 - type: entity
   id: SMES
diff --git a/Resources/Scenes/Power/Apc.tscn b/Resources/Scenes/Power/Apc.tscn
new file mode 100644
index 0000000000..f15cfb4a26
--- /dev/null
+++ b/Resources/Scenes/Power/Apc.tscn
@@ -0,0 +1,230 @@
+[gd_scene load_steps=2 format=2]
+
+[ext_resource path="res://Scenes/SS14Window/SS14Window.tscn" type="PackedScene" id=1]
+
+[node name="SS14Window" index="0" instance=ExtResource( 1 )]
+margin_right = 426.0
+margin_bottom = 270.0
+rect_clip_content = false
+
+[node name="Contents" parent="." index="0"]
+rect_clip_content = false
+
+[node name="Rows" type="VBoxContainer" parent="Contents" index="0"]
+anchor_left = 0.0
+anchor_top = 0.0
+anchor_right = 1.0
+anchor_bottom = 1.0
+rect_pivot_offset = Vector2( 0, 0 )
+rect_clip_content = false
+mouse_filter = 2
+mouse_default_cursor_shape = 0
+size_flags_horizontal = 1
+size_flags_vertical = 1
+alignment = 0
+
+[node name="StatusHeader" type="Label" parent="Contents/Rows" index="0"]
+anchor_left = 0.0
+anchor_top = 0.0
+anchor_right = 0.0
+anchor_bottom = 0.0
+margin_right = 306.0
+margin_bottom = 14.0
+rect_pivot_offset = Vector2( 0, 0 )
+rect_clip_content = false
+mouse_filter = 2
+mouse_default_cursor_shape = 0
+size_flags_horizontal = 1
+size_flags_vertical = 4
+text = "Power Status:"
+percent_visible = 1.0
+lines_skipped = 0
+max_lines_visible = -1
+
+[node name="Breaker" type="HBoxContainer" parent="Contents/Rows" index="1"]
+anchor_left = 0.0
+anchor_top = 0.0
+anchor_right = 0.0
+anchor_bottom = 0.0
+margin_top = 18.0
+margin_right = 306.0
+margin_bottom = 58.0
+rect_pivot_offset = Vector2( 0, 0 )
+rect_clip_content = false
+mouse_filter = 1
+mouse_default_cursor_shape = 0
+size_flags_horizontal = 1
+size_flags_vertical = 1
+alignment = 0
+
+[node name="Label" type="Label" parent="Contents/Rows/Breaker" index="0"]
+anchor_left = 0.0
+anchor_top = 0.0
+anchor_right = 0.0
+anchor_bottom = 0.0
+margin_top = 13.0
+margin_right = 100.0
+margin_bottom = 27.0
+rect_min_size = Vector2( 100, 0 )
+rect_pivot_offset = Vector2( 0, 0 )
+rect_clip_content = false
+mouse_filter = 2
+mouse_default_cursor_shape = 0
+size_flags_horizontal = 1
+size_flags_vertical = 4
+text = "Main Breaker:"
+percent_visible = 1.0
+lines_skipped = 0
+max_lines_visible = -1
+_sections_unfolded = [ "Rect" ]
+
+[node name="Breaker" type="CheckButton" parent="Contents/Rows/Breaker" index="1"]
+anchor_left = 0.0
+anchor_top = 0.0
+anchor_right = 0.0
+anchor_bottom = 0.0
+margin_left = 104.0
+margin_right = 180.0
+margin_bottom = 40.0
+rect_pivot_offset = Vector2( 0, 0 )
+rect_clip_content = false
+focus_mode = 2
+mouse_filter = 0
+mouse_default_cursor_shape = 0
+size_flags_horizontal = 1
+size_flags_vertical = 1
+toggle_mode = true
+pressed = true
+enabled_focus_mode = 2
+shortcut = null
+group = null
+flat = false
+align = 0
+
+[node name="ExternalStatus" type="HBoxContainer" parent="Contents/Rows" index="2"]
+anchor_left = 0.0
+anchor_top = 0.0
+anchor_right = 0.0
+anchor_bottom = 0.0
+margin_top = 62.0
+margin_right = 306.0
+margin_bottom = 76.0
+rect_pivot_offset = Vector2( 0, 0 )
+rect_clip_content = false
+mouse_filter = 1
+mouse_default_cursor_shape = 0
+size_flags_horizontal = 1
+size_flags_vertical = 1
+alignment = 0
+
+[node name="Label" type="Label" parent="Contents/Rows/ExternalStatus" index="0"]
+anchor_left = 0.0
+anchor_top = 0.0
+anchor_right = 0.0
+anchor_bottom = 0.0
+margin_right = 100.0
+margin_bottom = 14.0
+rect_min_size = Vector2( 100, 0 )
+rect_pivot_offset = Vector2( 0, 0 )
+rect_clip_content = false
+mouse_filter = 2
+mouse_default_cursor_shape = 0
+size_flags_horizontal = 1
+size_flags_vertical = 4
+text = "External Power:"
+percent_visible = 1.0
+lines_skipped = 0
+max_lines_visible = -1
+_sections_unfolded = [ "Rect" ]
+
+[node name="Status" type="Label" parent="Contents/Rows/ExternalStatus" index="1"]
+anchor_left = 0.0
+anchor_top = 0.0
+anchor_right = 0.0
+anchor_bottom = 0.0
+margin_left = 104.0
+margin_right = 138.0
+margin_bottom = 14.0
+rect_pivot_offset = Vector2( 0, 0 )
+rect_clip_content = false
+mouse_filter = 2
+mouse_default_cursor_shape = 0
+size_flags_horizontal = 1
+size_flags_vertical = 4
+text = "Good"
+percent_visible = 1.0
+lines_skipped = 0
+max_lines_visible = -1
+
+[node name="Charge" type="HBoxContainer" parent="Contents/Rows" index="3"]
+anchor_left = 0.0
+anchor_top = 0.0
+anchor_right = 0.0
+anchor_bottom = 0.0
+margin_top = 80.0
+margin_right = 306.0
+margin_bottom = 94.0
+rect_pivot_offset = Vector2( 0, 0 )
+rect_clip_content = false
+mouse_filter = 1
+mouse_default_cursor_shape = 0
+size_flags_horizontal = 1
+size_flags_vertical = 1
+alignment = 0
+
+[node name="Label" type="Label" parent="Contents/Rows/Charge" index="0"]
+anchor_left = 0.0
+anchor_top = 0.0
+anchor_right = 0.0
+anchor_bottom = 0.0
+margin_right = 100.0
+margin_bottom = 14.0
+rect_min_size = Vector2( 100, 0 )
+rect_pivot_offset = Vector2( 0, 0 )
+rect_clip_content = false
+mouse_filter = 2
+mouse_default_cursor_shape = 0
+size_flags_horizontal = 1
+size_flags_vertical = 4
+text = "Charge:"
+percent_visible = 1.0
+lines_skipped = 0
+max_lines_visible = -1
+_sections_unfolded = [ "Rect" ]
+
+[node name="Charge" type="ProgressBar" parent="Contents/Rows/Charge" index="1"]
+anchor_left = 0.0
+anchor_top = 0.0
+anchor_right = 0.0
+anchor_bottom = 0.0
+margin_left = 104.0
+margin_right = 306.0
+margin_bottom = 14.0
+rect_pivot_offset = Vector2( 0, 0 )
+rect_clip_content = false
+mouse_filter = 0
+mouse_default_cursor_shape = 0
+size_flags_horizontal = 3
+size_flags_vertical = 0
+min_value = 0.0
+max_value = 1.0
+step = 1.0
+page = 0.0
+value = 0.5
+exp_edit = false
+rounded = false
+allow_greater = false
+allow_lesser = false
+percent_visible = true
+_sections_unfolded = [ "Percent" ]
+
+[node name="Header" parent="." index="1"]
+editor/display_folded = true
+rect_clip_content = false
+
+[node name="Header Text" parent="Header" index="0"]
+rect_clip_content = false
+
+[node name="CloseButton" parent="Header" index="1"]
+rect_clip_content = false
+
diff --git a/engine b/engine
index b5bbbd9dde..a1f3c5fdbb 160000
--- a/engine
+++ b/engine
@@ -1 +1 @@
-Subproject commit b5bbbd9dde8a1ade222a9f52d151f69d2f900e38
+Subproject commit a1f3c5fdbb87961610cad0f9e4e954f6683218ca