When an electrician orders materials for a job, they're not just picking whatever is available on the shelf. Residential electrical work relies on specific components—panels, breakers, wire, fixtures, switches—and each one has standards it has to meet. This page walks through what actually goes into the work and why the choices matter to your home's safety and reliability.
You'll notice if you watch a professional do this work that they're particular about what they use. That's not being picky; it's following code and ensuring the installation will work consistently for years without trouble.
Wire gauge determines how much current can safely flow through without overheating. A thicker wire can handle more current, but it's also more expensive and harder to work with. A 15-amp circuit doesn't need 10-gauge wire—it's designed for 14-gauge, and oversizing every circuit makes the installation more complex and costly without adding safety. The breaker matching the wire gauge is what keeps you safe.
Your main panel is where power enters your home from the utility and gets distributed to different circuits. A sub-panel is a secondary panel fed from the main panel, usually added when you need more circuits in a specific area—like a garage or addition. A sub-panel still needs its own breaker in the main panel and proper grounding, which is why they're not a DIY project.
A licensed electrician can inspect the panel and test it. They're looking for proper bonding, correct breaker sizing, no signs of burning or corrosion, and whether the breaker configuration matches the wiring it protects. If the panel is more than 40 years old, most electricians recommend a replacement as a safety measure, even if it's still working.
A 200-amp main service means your home can draw up to 200 amps at once. Homes built before the 1990s often had 100-amp service, which is tight if you're running multiple high-load appliances at once—especially with air conditioning, electric range, and water heater. If you're upgrading to all-electric heat or adding major appliances, jumping to 200 amps makes sense. For basic needs, 100 amps can work, but there's no harm in having more capacity available.
The certification mark you're actually looking for on a breaker or outlet box—this is who tests them. UL is the standards body behind those little marks you see on electrical equipment. Understanding their certifications helps you recognize quality components.
Worth checking before a panel upgrade—some efficient-equipment choices come with a rebate attached. If you're planning electrical work that involves new appliances or a panel upgrade, ENERGY STAR can point you to options that qualify for state or federal rebates.