Scope and licensing: C-10 versus C-7 and C-46, low voltage, data and AV, incidental work, and what requires which license
In one paragraph
Your C-10 covers anything that generates, transmits, transforms or uses electrical energy, at any voltage, which is why the C-7 low-voltage license is defined by what it cannot touch (anything over 91 volts, and fire alarm systems) and the C-46 solar license by what it cannot do (other trades except as needed for the solar system). The lesson draws the lines that matter on a residential job: data, AV and low-voltage lighting are inside the C-10 and also available to a C-7; fire alarm is C-10; a solar array is either license, but the service upgrade and the storage interconnection are yours; the drywall patch and the trench are incidental only when they are small and necessary to your electrical work; and a general building contractor may not take a single-trade electrical job as a prime unless it holds a C-10 or subs it to one. Working outside your classification is a disciplinary cause by itself, and so is hiring a sub who is not licensed for what you hired them to do.
The rule
A C-10 electrical contractor may place, install, erect or connect any electrical wires, fixtures, appliances, apparatus, raceways, conduits, solar photovoltaic cells or any part thereof that generate, transmit, transform or utilize electrical energy (16 CCR 832.10); a C-7 is limited to energy-limited communication and low-voltage systems not exceeding 91 volts and excludes fire alarm systems (832.07); a C-46 installs solar systems only (832.46). A specialty contractor may perform work in other crafts only when it is incidental and supplemental to its own (B&P 7059(a)); acting in a classification not held is cause for discipline (7117.6), and so is contracting with an unlicensed contractor (7118).
Why it matters
The C-10 is the broadest specialty license on a house, and the temptation is to treat it as a general license: patch the wall, pour the pad, hang the TV mount, run the low-voltage for the alarm company's panel. Some of that is incidental and legal, some of it is another license's work, and the line between them is a disciplinary cause and an uninsured claim. Knowing where your license ends is also how you know what to subcontract, and to whom.