How to Read Your Own Electrical Panel

Start with the main

The largest breaker, usually alone at the top or the bottom, is the main. The number on it is the whole capacity of the house. One hundred amps was standard for decades and is tight for a modern home. Two hundred is the common target today.

Under it sit the branch breakers, each with a number, normally 15 or 20 for lights and outlets and 30 to 50 for large appliances.

What the labels should say

A good panel has every breaker labeled with a room and a purpose, like kitchen counter east or bedroom two. Most panels have labels written by someone who is no longer around and are wrong in at least three places.

Fixing that is a nice weekend job with a helper and a phone. Turn one breaker off, walk the house, write down what died. It pays for itself the first time you need to work on something fast.

Signs of trouble you can see

Rust at the bottom of the box means water got in. Brown or black marks around a breaker mean heat. A smell like hot plastic means stop now. A breaker that feels loose or will not stay on is failing.

Look for two breakers taking up one slot. Those thin tandem breakers are legal in panels rated for them and a warning sign in panels that are not, because it usually means someone ran out of room.

Panels with a bad name

Federal Pacific Stab Lok and Zinsco panels were installed widely across Southern California and both have a documented record of breakers that do not trip when they should. Challenger and some Sylvania panels come up too.

The brand is printed inside the door. If yours is on that list, get an electrician to look. Insurance companies ask about these by name and the answer changes what you pay.