# LDD-09 · Electrical System

> **Status:** 🟢 LOCKED at infrastructure level.

## One-line intent

Distributed, zone-aligned electrical with centralized service and localized subpanels — no over-centralized "smart house" dependency.

## Why this matters

Electrical decisions made now are 50-year decisions. Getting the panel capacity, subpanel layout, conduit routing, EV/solar/generator-ready strategy locked at LDD stage is the right move and prevents 80% of regret-driven retrofit cost downstream.

## Locked decisions

**Service capacity**

- Target: **300A–400A** service
- Supports multiple HVAC, EV charging on all bays, solar integration, future expansion

**Main panel**

- Location: laundry / operations core (north service zone)
- Functions as central distribution hub
- Aligns with plumbing + HVAC core

**Subpanels**

| Subpanel | Serves | Reason |
|---|---|---|
| ILS subpanel | Full ILS unit + appliances + ILS HVAC + ILS garage | Independent living capability |
| Workshop / LOW subpanel | Workshop equipment + LOW + lift + future loads | Isolates high and variable loads |

**EV infrastructure**

- Main garage: 3 bays EV-ready
- ILS garage: 2 bays EV-ready
- Conduit installed at build; panel capacity reserved

**Solar + generator ready**

- Solar: grid-tied ready, inverter space allocated
- Generator: future install, transfer-ready panel

**HVAC electrical**

- All HVAC systems on dedicated circuits (ducted, mini-splits, radiant, destratification fans)

**Lighting integration**

- Zone-based layout
- Scene control (not switch clutter)

**Routing rules**

- Conduit aligned with structure
- Parallel runs only
- Vertical drops only
- No diagonal runs or messy routing

## Open items / requires engineer review

- **Service size: 300A or 400A?** Pick one. At 400A the panel and meter are physically larger, but headroom is meaningfully better for 5 EV bays + future shop equipment + heat pumps.
- **EV charger level (Level 2 7.7kW vs 11.5kW vs 19.2kW)** — affects circuit sizing.
- **Generator size and fuel** — propane, natural gas, diesel? Major affordability / availability decision.
- **Solar PV system size** — roof area available, target offset?
- **Surge protection** at main + each subpanel — strongly recommended, not in current LDD.
- **Whole-house grounding** strategy — important for low-voltage lighting and AV.
- **Number of total circuits** by zone, including kitchen GFCI requirements (every counter outlet), bathroom GFCI, garage GFCI, etc.

## Cross-references

- ← [LDD-08 lighting](08-lighting-framework.md) — lighting on dedicated low-voltage control circuits.
- ← [LDD-05 HVAC](05-hvac-system.md) — dedicated circuits per HVAC system.
- ← [LDD-21 laundry / ops](21-laundry-ops.md) — main panel sited here.
- → [LDD-23 build rules](23-build-rules.md) — conduit routing follows constraint discipline.

## Cost drivers

- **400A service entrance + main panel**: $8–15K (vs $4–8K for 200A). Conduit from transformer also gets larger.
- **Two subpanels with feeders and breakers**: $4–8K combined.
- **EV conduit + panel capacity reservation** (no chargers installed in Phase 1): $2–4K for stub-outs to 5 bays. Cheap insurance.
- **Solar PV-ready** (inverter space, conduit from roof to inverter location, AC disconnect, interconnection breaker): $1–3K — also cheap insurance.
- **Generator transfer-ready** (manual transfer switch + generator inlet box): $2–4K.
- **Whole-house wiring + devices + lighting power**: $60–95K for a project this size with this fixture density (excluding LDD-08 lighting fixtures, which are budgeted separately).

**Likely-case rollup: $75–125K total electrical infrastructure**, budgeted at $110K in the waterfall.

## Air-gap concerns

1. **300A vs 400A: pick now.** Upgrading service entrance later is expensive ($8–15K and 2-3 weeks downtime). Default to 400A given heat pumps + 5 EV bays + workshop loads.
2. **No mention of low-voltage / structured wiring.** Cat6 runs to every TV, AP location, doorbell, intercom. Adds $4–10K and is much easier to install in rough than to retrofit. The LDD framework implies a controls system but doesn't specify the network backbone.
3. **No mention of surge protection.** Whole-house surge protector at the main + each subpanel: $400–1,200 installed. Without it, the low-voltage lighting drivers and any electronics are at risk during a regional surge event.
4. **No mention of grounding strategy for the metal shell.** A PEMB is a giant Faraday cage if properly bonded. Coordinate with electrical engineer; can be helpful for lightning safety in some regions.
5. **Workshop subpanel sizing.** "Future loads" is vague. A real woodshop with table saw + dust collection + compressor + welder + future CNC can easily pull 100–150A. Spec the workshop subpanel at 100A minimum; 125A if there's any chance of a welder or CNC.
6. **Generator inlet not yet sited.** If the future generator is propane or natural gas, the gas line stub-out also needs to be in Phase 1. Coordinate with plumbing.

## Diagram

(no dedicated SVG — electrical infrastructure follows structural grid; see [building footprint](../../diagrams/01-building-footprint.svg))

## Status

🟢 **Green — infrastructure strategy is correct.** Pick service size (recommend 400A), add surge + low-voltage Cat6 to the LDD before bidding.