Home Wiring Guide
Understanding your home's electrical system. Learn about wiring types, circuits, panel upgrades, and when rewiring is necessary.
Critical Safety Warning
Electrical work is dangerous and requires proper training. In Denver, most electrical work requires a permit and inspection. Improper wiring causes thousands of house fires annually. Always hire a licensed electrician for anything beyond basic outlet/switch replacement.
Common Wire Types
| Wire Type | Common Use | Description |
|---|---|---|
| NM-B (Romex) | Most interior wiring | Non-metallic sheathed cable for dry locations inside walls |
| UF-B | Underground/outdoor | Underground feeder cable for direct burial applications |
| THHN/THWN | Conduit runs | Individual wires run through metal or PVC conduit |
| MC Cable | Commercial/exposed | Metal-clad cable for exposed locations or commercial use |
| Service Entrance | Main power feed | Heavy-gauge cable from utility to main panel |
Circuit Types & Requirements
| Circuit Type | Wire Size | Typical Use | Notes |
|---|---|---|---|
| 15-Amp General | 14 AWG | Lighting, general outlets | Most common residential circuit |
| 20-Amp General | 12 AWG | Kitchen, bathroom outlets | Required for small appliances |
| 20-Amp Dedicated | 12 AWG | Dishwasher, disposal, microwave | Single appliance per circuit |
| 30-Amp 240V | 10 AWG | Dryer, water heater | Large appliances |
| 40-Amp 240V | 8 AWG | Electric range, large AC | High-demand appliances |
| 50-Amp 240V | 6 AWG | Electric range, EV charger | Very high demand |
Signs You Need a Panel Upgrade
- Breakers trip frequently
- Fuse box instead of circuit breakers
- 100-amp service with modern electrical demands
- Adding major appliances (EV charger, AC, hot tub)
- Burning smell or warm panel
- Visible corrosion or damage
- Insufficient circuits for needs
- Planning home addition or major renovation
Denver Electrical Code Requirements
- All electrical work requires a permit from Denver Building Department
- GFCI protection required in kitchens, bathrooms, garages, outdoors, basements
- AFCI protection required for bedrooms and living areas
- Tamper-resistant receptacles required in new construction
- Smoke and CO detectors must be hardwired with battery backup
- Panel must be accessible with 36" clearance in front
- Outdoor outlets must be weather-resistant (WR) rated
When to Consider Rewiring
Knob and tube wiring
Pre-1950s wiring that lacks grounding and is a fire hazard
Aluminum wiring (1965-1973)
Prone to overheating at connections
Frequently tripping breakers
May indicate overloaded or damaged circuits
Flickering lights
Can indicate loose connections or overloaded circuits
Burning smell from outlets
Immediate fire hazard - call electrician now
Discolored outlets/switches
Sign of heat damage from poor connections
Two-prong ungrounded outlets
Lack of grounding creates safety hazard
Sparking when plugging in devices
Indicates damaged outlets or wiring
More Electrical Information
Learn about lighting options and electrical safety for your Denver home.