diff --git a/sim/allocator.ts b/sim/allocator.ts
index 1881a14f..813ca724 100644
--- a/sim/allocator.ts
+++ b/sim/allocator.ts
@@ -195,12 +195,14 @@ namespace pxsim {
             const GROUND_COLOR = "blue";
             const POWER_COLOR = "red";
             const wires: WireInst[] = [];
+            let groundStep = 0;
+            let threeVoltStep = (powerUsage.bottomGround || powerUsage.topGround) ? 1 : 0;
             if (powerUsage.bottomGround && powerUsage.topGround) {
                 //bb top - <==> bb bot -
                 wires.push({
                     start: this.allocateLocation("ground", {nearestBBPin: top}),
                     end: this.allocateLocation("ground", {nearestBBPin: bot}),
-                    color: GROUND_COLOR, assemblyStep: 0
+                    color: GROUND_COLOR, assemblyStep: groundStep
                 });
             }
             if (powerUsage.topGround) {
@@ -208,14 +210,14 @@ namespace pxsim {
                 wires.push({
                     start: this.allocateLocation("ground", {nearestBBPin: top}),
                     end: {type: "dalboard", pin: boardGround},
-                    color: GROUND_COLOR, assemblyStep: 0
+                    color: GROUND_COLOR, assemblyStep: groundStep
                 });
             } else if (powerUsage.bottomGround) {
                 //board - <==> bb bot -
                 wires.push({
                     start: this.allocateLocation("ground", {nearestBBPin: bot}),
                     end: {type: "dalboard", pin: boardGround},
-                    color: GROUND_COLOR, assemblyStep: 0
+                    color: GROUND_COLOR, assemblyStep: groundStep
                 });
             }
             if (powerUsage.bottomThreeVolt && powerUsage.bottomGround) {
@@ -223,7 +225,7 @@ namespace pxsim {
                 wires.push({
                     start: this.allocateLocation("threeVolt", {nearestBBPin: top}),
                     end: this.allocateLocation("threeVolt", {nearestBBPin: bot}),
-                    color: POWER_COLOR, assemblyStep: 1
+                    color: POWER_COLOR, assemblyStep: threeVoltStep
                 });
             }
             if (powerUsage.topThreeVolt) {
@@ -231,14 +233,14 @@ namespace pxsim {
                 wires.push({
                     start: this.allocateLocation("threeVolt", {nearestBBPin: top}),
                     end: {type: "dalboard", pin: threeVoltPin},
-                    color: POWER_COLOR, assemblyStep: 1
+                    color: POWER_COLOR, assemblyStep: threeVoltStep
                 });
             } else if (powerUsage.bottomThreeVolt) {
                 //board + <==> bb bot +
                 wires.push({
                     start: this.allocateLocation("threeVolt", {nearestBBPin: bot}),
                     end: {type: "dalboard", pin: threeVoltPin},
-                    color: POWER_COLOR, assemblyStep: 1
+                    color: POWER_COLOR, assemblyStep: threeVoltStep
                 });
             }
             return wires;
diff --git a/sim/instructions/instructions.ts b/sim/instructions/instructions.ts
index 431e8477..f2724e65 100644
--- a/sim/instructions/instructions.ts
+++ b/sim/instructions/instructions.ts
@@ -321,7 +321,7 @@ namespace pxsim.instructions {
             (stepToWires[step] || (stepToWires[step] = [])).push(w)
         });
         let getMaxStep = (ns: {assemblyStep: number}[]) => ns.reduce((m, n) => Math.max(m, n.assemblyStep), 0);
-        let stepOffset = getMaxStep(powerWires) + 2;
+        let stepOffset = powerWires.length > 0 ? getMaxStep(powerWires) + 2 : 1;
         components.forEach(cAndWs => {
             let {component, wires} = cAndWs;
             let cStep = component.assemblyStep + stepOffset;