diff --git a/src/domain/services/project-device-placement.service.ts b/src/domain/services/project-device-placement.service.ts
index 3bf2123..ba47974 100644
--- a/src/domain/services/project-device-placement.service.ts
+++ b/src/domain/services/project-device-placement.service.ts
@@ -1,6 +1,7 @@
+import type { CircuitGroupCategory } from "../../shared/constants/circuit-group.js";
+
 export interface ProjectDevicePlacementSource {
-  category?: string | null;
-  phaseType: "single_phase" | "three_phase";
+  category: CircuitGroupCategory;
 }
 
 export interface ProjectDevicePlacementSection {
@@ -14,11 +15,13 @@ export type DefaultCircuitSectionKey = "lighting" | "single_phase" | "three_phas
 export function inferProjectDeviceSectionKey(
   device: ProjectDevicePlacementSource
 ): DefaultCircuitSectionKey {
-  const category = (device.category ?? "").trim().toLowerCase();
-  if (category.includes("light") || category.includes("beleuchtung")) {
-    return "lighting";
-  }
-  return device.phaseType;
+  return device.category;
+}
+
+export function resolveProjectDevicePhaseType(
+  category: CircuitGroupCategory
+): "single_phase" | "three_phase" {
+  return category === "three_phase" ? "three_phase" : "single_phase";
 }
 
 export function isProjectDevicePlacementValid(
diff --git a/src/frontend/components/circuit-tree-editor.tsx b/src/frontend/components/circuit-tree-editor.tsx
index 3ecaf16..b63cd8e 100644
--- a/src/frontend/components/circuit-tree-editor.tsx
+++ b/src/frontend/components/circuit-tree-editor.tsx
@@ -3258,7 +3258,6 @@ export function CircuitTreeEditor(props: { projectId: string; circuitListId: str
               >
                 <strong>{device.displayName || device.name}</strong>
                 <span>Name: {device.name}</span>
-                <span>Phasenart: {formatPhaseTypeLabel(device.phaseType)}</span>
                 <span>Anzahl: {formatValue(device.quantity, "quantity")}</span>
                 <span>
                   Leistung/Gerät: {formatValue(device.powerPerUnit, "powerPerUnit")} kW
@@ -3271,7 +3270,7 @@ export function CircuitTreeEditor(props: { projectId: string; circuitListId: str
                   Gesamtleistung: {formatValue(device.totalPower, "rowTotalPower")} kW
                 </span>
                 <span>Kostengruppe: {device.costGroup || "-"}</span>
-                <span>Kategorie: {device.category || "-"}</span>
+                <span>Kategorie: {circuitGroupCategoryLabels[device.category]}</span>
               </button>
             ))}
             {searchableProjectDevices.length === 0 ? <p className="notice muted">Keine passenden Projektgeräte gefunden.</p> : null}
diff --git a/src/frontend/components/project-device-modal.tsx b/src/frontend/components/project-device-modal.tsx
index 907fffe..55c9d25 100644
--- a/src/frontend/components/project-device-modal.tsx
+++ b/src/frontend/components/project-device-modal.tsx
@@ -7,6 +7,11 @@ import type {
   ProjectDeviceDto,
 } from "../types";
 import { FormModal } from "./form-modal";
+import {
+  circuitGroupCategories,
+  circuitGroupCategoryLabels,
+  type CircuitGroupCategory,
+} from "../../shared/constants/circuit-group";
 
 interface ProjectDeviceModalProps {
   globalDevices: GlobalDeviceDto[];
@@ -37,14 +42,12 @@ export function ProjectDeviceModal({
     await onSave({
       name: values.name.trim(),
       displayName: values.displayName.trim() || values.name.trim(),
-      phaseType:
-        values.phaseType === "three_phase" ? "three_phase" : "single_phase",
       connectionKind: optionalString(values.connectionKind),
       costGroup: optionalString(values.costGroup),
-      category: optionalString(values.category),
-      quantity: Number(values.quantity),
-      powerPerUnit: Number(values.powerPerUnit),
-      simultaneityFactor: Number(values.simultaneityFactor),
+      category: values.category as CircuitGroupCategory,
+      quantity: parseDecimal(values.quantity),
+      powerPerUnit: parseDecimal(values.powerPerUnit),
+      simultaneityFactor: parseDecimal(values.simultaneityFactor),
       cosPhi: optionalNumber(values.cosPhi),
       remark: optionalString(values.remark),
     });
@@ -52,10 +55,10 @@ export function ProjectDeviceModal({
 
   const isValid =
     values.name.trim().length > 0 &&
-    Number(values.quantity) >= 0 &&
-    Number(values.powerPerUnit) >= 0 &&
-    Number(values.simultaneityFactor) >= 0 &&
-    Number(values.simultaneityFactor) <= 1;
+    isNumberInRange(values.quantity, 0) &&
+    isNumberInRange(values.powerPerUnit, 0) &&
+    isNumberInRange(values.simultaneityFactor, 0, 1) &&
+    (!values.cosPhi.trim() || isNumberInRange(values.cosPhi, 0, 1));
 
   return (
     <FormModal
@@ -116,12 +119,25 @@ export function ProjectDeviceModal({
           onChange={(value) => update("displayName", value)}
           value={values.displayName}
         />
-        <TextField
-          id="device-category"
-          label="Kategorie"
-          onChange={(value) => update("category", value)}
-          value={values.category}
-        />
+        <div className="col-12 col-md-6">
+          <label className="form-label" htmlFor="device-category">
+            Kategorie
+          </label>
+          <select
+            className="form-select"
+            id="device-category"
+            onChange={(event) =>
+              update("category", event.target.value as CircuitGroupCategory)
+            }
+            value={values.category}
+          >
+            {circuitGroupCategories.map((category) => (
+              <option key={category} value={category}>
+                {circuitGroupCategoryLabels[category]}
+              </option>
+            ))}
+          </select>
+        </div>
         <TextField
           id="device-connection"
           label="Anschlussart"
@@ -134,20 +150,6 @@ export function ProjectDeviceModal({
           onChange={(value) => update("costGroup", value)}
           value={values.costGroup}
         />
-        <div className="col-12 col-md-6">
-          <label className="form-label" htmlFor="device-phase-type">
-            Phasenart
-          </label>
-          <select
-            className="form-select"
-            id="device-phase-type"
-            onChange={(event) => update("phaseType", event.target.value)}
-            value={values.phaseType}
-          >
-            <option value="single_phase">1-phasig</option>
-            <option value="three_phase">3-phasig</option>
-          </select>
-        </div>
         <NumberField
           id="device-quantity"
           label="Anzahl"
@@ -244,7 +246,8 @@ function NumberField({
         min={min}
         onChange={(event) => onChange(event.target.value)}
         step={step}
-        type="number"
+        inputMode="decimal"
+        type="text"
         value={value}
       />
     </div>
@@ -255,10 +258,9 @@ function toFormValues(device?: ProjectDeviceDto) {
   return {
     name: device?.name ?? "",
     displayName: device?.displayName ?? "",
-    phaseType: device?.phaseType ?? "single_phase",
     connectionKind: device?.connectionKind ?? "",
     costGroup: device?.costGroup ?? "",
-    category: device?.category ?? "",
+    category: device?.category ?? "single_phase",
     quantity: String(device?.quantity ?? 1),
     powerPerUnit: String(device?.powerPerUnit ?? 0.1),
     simultaneityFactor: String(device?.simultaneityFactor ?? 1),
@@ -272,5 +274,14 @@ function optionalString(value: string) {
 }
 
 function optionalNumber(value: string) {
-  return value.trim() ? Number(value) : undefined;
+  return value.trim() ? parseDecimal(value) : undefined;
+}
+
+function parseDecimal(value: string) {
+  return Number(value.trim().replace(",", "."));
+}
+
+function isNumberInRange(value: string, min: number, max = Number.POSITIVE_INFINITY) {
+  const parsed = parseDecimal(value);
+  return Number.isFinite(parsed) && parsed >= min && parsed <= max;
 }
diff --git a/src/frontend/types.ts b/src/frontend/types.ts
index ee58d0d..f7ab550 100644
--- a/src/frontend/types.ts
+++ b/src/frontend/types.ts
@@ -173,7 +173,7 @@ export interface ProjectDeviceDto {
   phaseType: "single_phase" | "three_phase";
   connectionKind: string | null;
   costGroup: string | null;
-  category: string | null;
+  category: CircuitGroupCategory;
   quantity: number;
   powerPerUnit: number;
   simultaneityFactor: number;
@@ -218,10 +218,9 @@ export interface CreateGlobalDeviceInput {
 export interface CreateProjectDeviceInput {
   name: string;
   displayName: string;
-  phaseType: "single_phase" | "three_phase";
   connectionKind?: string;
   costGroup?: string;
-  category?: string;
+  category: CircuitGroupCategory;
   quantity: number;
   powerPerUnit: number;
   simultaneityFactor: number;
diff --git a/src/server/controllers/project-device.controller.ts b/src/server/controllers/project-device.controller.ts
index 2878f61..b10e718 100644
--- a/src/server/controllers/project-device.controller.ts
+++ b/src/server/controllers/project-device.controller.ts
@@ -23,6 +23,8 @@ import {
 import type { CreateProjectDeviceInput } from "../../shared/validation/project-device.schemas.js";
 import { respondWithProjectCommandError } from "./project-command.controller.js";
 import { resolveProjectVoltage } from "../../domain/services/project-voltage.service.js";
+import { resolveProjectDevicePhaseType } from "../../domain/services/project-device-placement.service.js";
+import type { CircuitGroupCategory } from "../../shared/constants/circuit-group.js";
 
 export async function listProjectDevicesByProject(req: Request, res: Response) {
   const { projectId } = req.params;
@@ -156,8 +158,10 @@ export async function copyGlobalDeviceToProject(req: Request, res: Response) {
   const projectDevice = toProjectDeviceSnapshot(projectId, randomUUID(), {
     name: source.name,
     displayName: source.displayName,
-    phaseType: source.phaseCount === 3 ? "three_phase" : "single_phase",
-    category: source.category ?? undefined,
+    category: inferImportedProjectDeviceCategory(
+      source.category,
+      source.phaseCount
+    ),
     quantity: source.quantity,
     powerPerUnit: source.installedPowerPerUnitKw,
     simultaneityFactor: source.demandFactor,
@@ -205,22 +209,34 @@ function toProjectDeviceValues(
     threePhaseVoltageV: number;
   }
 ) {
+  const phaseType = resolveProjectDevicePhaseType(input.category);
   return {
     name: input.name,
     displayName: input.displayName,
-    phaseType: input.phaseType,
+    phaseType,
     connectionKind: input.connectionKind ?? null,
     costGroup: input.costGroup ?? null,
-    category: input.category ?? null,
+    category: input.category,
     quantity: input.quantity,
     powerPerUnit: input.powerPerUnit,
     simultaneityFactor: input.simultaneityFactor,
     cosPhi: input.cosPhi ?? null,
     remark: input.remark ?? null,
-    voltageV: resolveProjectVoltage(input.phaseType, project),
+    voltageV: resolveProjectVoltage(phaseType, project),
   };
 }
 
+function inferImportedProjectDeviceCategory(
+  category: string | null,
+  phaseCount: number | null
+): CircuitGroupCategory {
+  const normalized = category?.trim().toLowerCase() ?? "";
+  if (normalized.includes("light") || normalized.includes("beleuchtung")) {
+    return "lighting";
+  }
+  return phaseCount === 3 ? "three_phase" : "single_phase";
+}
+
 export async function getProjectDeviceSyncPreview(req: Request, res: Response) {
   const { projectId, projectDeviceId } = req.params;
   if (typeof projectId !== "string" || typeof projectDeviceId !== "string") {
diff --git a/src/shared/validation/project-device.schemas.ts b/src/shared/validation/project-device.schemas.ts
index f252502..da6bf65 100644
--- a/src/shared/validation/project-device.schemas.ts
+++ b/src/shared/validation/project-device.schemas.ts
@@ -1,14 +1,14 @@
 import { z } from "zod";
 import { projectDeviceSyncFields } from "../constants/project-device-sync-fields.js";
 import { expectedProjectRevisionSchema } from "./project-command.schemas.js";
+import { circuitGroupCategories } from "../constants/circuit-group.js";
 
 export const createProjectDeviceSchema = z.object({
   name: z.string().min(1),
   displayName: z.string().min(1),
-  phaseType: z.enum(["single_phase", "three_phase"]),
   connectionKind: z.string().optional(),
   costGroup: z.string().optional(),
-  category: z.string().optional(),
+  category: z.enum(circuitGroupCategories),
   quantity: z.number().min(0),
   powerPerUnit: z.number().min(0),
   simultaneityFactor: z.number().min(0).max(1),
diff --git a/tests/project-device-placement.service.test.ts b/tests/project-device-placement.service.test.ts
index fef7ee6..6625ced 100644
--- a/tests/project-device-placement.service.test.ts
+++ b/tests/project-device-placement.service.test.ts
@@ -3,36 +3,27 @@ import { describe, it } from "node:test";
 import {
   inferProjectDeviceSectionKey,
   isProjectDevicePlacementValid,
+  resolveProjectDevicePhaseType,
 } from "../src/domain/services/project-device-placement.service.js";
 
 describe("project device placement", () => {
-  it("routes lighting categories to the lighting section before phase classification", () => {
-    assert.equal(
-      inferProjectDeviceSectionKey({ category: "Lighting", phaseType: "three_phase" }),
-      "lighting"
-    );
-    assert.equal(
-      inferProjectDeviceSectionKey({ category: "Beleuchtung", phaseType: "single_phase" }),
-      "lighting"
-    );
-  });
-
-  it("routes non-lighting devices by phase type", () => {
-    assert.equal(
-      inferProjectDeviceSectionKey({ category: "Socket", phaseType: "single_phase" }),
-      "single_phase"
-    );
-    assert.equal(
-      inferProjectDeviceSectionKey({ category: "Motor", phaseType: "three_phase" }),
-      "three_phase"
-    );
+  it("routes project devices by their required category", () => {
+    assert.equal(inferProjectDeviceSectionKey({ category: "lighting" }), "lighting");
+    assert.equal(inferProjectDeviceSectionKey({ category: "single_phase" }), "single_phase");
+    assert.equal(inferProjectDeviceSectionKey({ category: "three_phase" }), "three_phase");
   });
 
   it("accepts only the inferred default section", () => {
-    const device = { category: "Motor", phaseType: "three_phase" as const };
+    const device = { category: "three_phase" as const };
 
     assert.equal(isProjectDevicePlacementValid(device, { key: "three_phase" }), true);
     assert.equal(isProjectDevicePlacementValid(device, { key: "single_phase" }), false);
     assert.equal(isProjectDevicePlacementValid(device, { key: "unassigned" }), false);
   });
+
+  it("derives the electrical phase type from the category", () => {
+    assert.equal(resolveProjectDevicePhaseType("lighting"), "single_phase");
+    assert.equal(resolveProjectDevicePhaseType("single_phase"), "single_phase");
+    assert.equal(resolveProjectDevicePhaseType("three_phase"), "three_phase");
+  });
 });
diff --git a/tests/project-device-schema.test.ts b/tests/project-device-schema.test.ts
index 7ee2f89..257170a 100644
--- a/tests/project-device-schema.test.ts
+++ b/tests/project-device-schema.test.ts
@@ -14,10 +14,9 @@ describe("project device circuit-first schema", () => {
     const result = createProjectDeviceSchema.safeParse({
       name: "E-Line Pro",
       displayName: "Office lighting",
-      phaseType: "single_phase",
       connectionKind: "fixed",
       costGroup: "440",
-      category: "Lighting",
+      category: "lighting",
       quantity: 6,
       powerPerUnit: 0.04,
       simultaneityFactor: 0.8,
@@ -28,7 +27,7 @@ describe("project device circuit-first schema", () => {
     assert.equal(result.success, true);
   });
 
-  it("requires the circuit-first power and phase fields", () => {
+  it("requires the circuit-first power and category fields", () => {
     const result = createProjectDeviceSchema.safeParse({
       name: "Test device",
       displayName: "Test device",
@@ -45,7 +44,7 @@ describe("project device circuit-first schema", () => {
     const result = createProjectDeviceSchema.safeParse({
       name: "Pumpe",
       displayName: "Pumpe",
-      phaseType: "three_phase",
+      category: "three_phase",
       quantity: 1,
       powerPerUnit: 2,
       simultaneityFactor: 1,
@@ -59,7 +58,7 @@ describe("project device circuit-first schema", () => {
     const device = {
       name: "E-Line Pro",
       displayName: "Bürobeleuchtung",
-      phaseType: "single_phase" as const,
+      category: "lighting" as const,
       quantity: 6,
       powerPerUnit: 0.04,
       simultaneityFactor: 0.8,
diff --git a/tests/project-version-history.test.ts b/tests/project-version-history.test.ts
index 300b972..bd6c615 100644
--- a/tests/project-version-history.test.ts
+++ b/tests/project-version-history.test.ts
@@ -283,7 +283,6 @@ describe("project device modal presentation", () => {
       "Kategorie",
       "Anschlussart",
       "Kostengruppe",
-      "Phasenart",
       "Anzahl",
       "Leistung je Stück [kW]",
       "Gleichzeitigkeitsfaktor",
@@ -292,6 +291,10 @@ describe("project device modal presentation", () => {
       assert.match(markup, new RegExp(label.replace("[", "\\[").replace("]", "\\]")));
     }
     assert.doesNotMatch(markup, /Spannung \[V\]/);
+    assert.doesNotMatch(markup, /Phasenart/);
+    assert.match(markup, /Beleuchtung/);
+    assert.match(markup, /1-phasig/);
+    assert.match(markup, /3-phasig/);
   });
 });