Service and panel
Residential service in California is typically 200 amps at 240 volts split-phase. The main panel divides the service into branch circuits. Each circuit is protected by a breaker sized to the wire and the load. Common breakers are 15 amp for lighting, 20 amp for receptacles and kitchen counters, and 30 to 50 amp for appliances.
Wire sizing
Wire size is given in AWG. Smaller number is larger wire. 14 AWG copper is rated for 15 amps, 12 AWG for 20 amps, 10 AWG for 30 amps. Aluminum wire is generally one size up for the same ampacity and is no longer used for branch circuits in homes.
Grounding and bonding
The grounding electrode system, usually a ground rod or Ufer ground in the foundation, gives fault current a path back to earth. Bonding ties metal piping and the panel together so they are all at the same potential. A poorly grounded system can be deadly even when everything seems to work.
Mini-quiz
Attempt 1 · 3 questions
Check your understanding. Passing is 70% — but you can keep going to the next lesson either way.
Question 1
Based on "Service and panel", which statement is correct?
Question 2
Based on "Service and panel", which statement is correct?
Question 3
Based on "Grounding and bonding", which statement is correct?