diff --git a/src/components/floor-plan/modal/circuitTrestle/step/PowerConditionalSelect.jsx b/src/components/floor-plan/modal/circuitTrestle/step/PowerConditionalSelect.jsx
index d8a517c5..0baa64f3 100644
--- a/src/components/floor-plan/modal/circuitTrestle/step/PowerConditionalSelect.jsx
+++ b/src/components/floor-plan/modal/circuitTrestle/step/PowerConditionalSelect.jsx
@@ -103,6 +103,11 @@ export default function PowerConditionalSelect(props) {
           selected: s.pcsSerCd === data.pcsSerCd ? !s.selected : data.pcsSerParallelYn === 'Y' ? s.selected : false,
         }
       })
+      // [PCS-SINGLE-RESET 2026-06-08] 併設(병설) 아닌 Single 아이템은 1대만 적산 가능.
+      //   체크박스 전환 시 기존 추가 PCS 가 리셋되지 않아 복수 등록되던 문제 → 비병설이면 selectedModels 리셋 (SINGLE_N 과 동일).
+      if (data.pcsSerParallelYn !== 'Y') {
+        setSelectedModels([])
+      }
     } else {
       copySeries = series.map((s) => {
         return {