Electrical (C-10) · Lesson 6 of 6

Standby Power, Generators and Back-Feed

"Standby Power, Generators and Back-Feed" is lesson 6 of 6 in the Electrical (C-10) Learning Hub. It opens with "Emergency versus standby timing" and works through 5 short steps, then a worked example you can check yourself against.

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Steps in this lesson

  1. Emergency versus standby timing
  2. How long the power must last
  3. Protecting critical circuits and elevators
  4. Portable generators and back-feed
  5. Maintenance, transfer switch test and records

The worked example in the course applies this lesson to a realistic job in 6 steps, from "Standby transfer time" through "Portable generator on site".

What you'll be able to do

  • Explain the main idea of "Standby Power, Generators and Back-Feed" in plain language you can use on the exam.
  • Apply this step with confidence: "Protecting critical circuits and elevators".
  • Apply this step with confidence: "Portable generators and back-feed".
  • Apply this step with confidence: "Maintenance, transfer switch test and records".
  • Test yourself on the worked example and the quick-check quiz inside the classroom.
Standby Power Timing, Duration and FuelHOW LONG THE POWER MUST RUNExit signs90 minDefault2 hHigh-rise (>75 ft)6 hResponder radio12 hEMERGENCY: 10 sSTANDBY: 60 sPORTABLE GENERATOR RULESOutdoors only, 5 ft from openingsand air intakesListed transfer switch; no back-feedthrough receptaclesGFCI on cords and temporary wiringNo refueling while runningExtinguisher 2-A:20-B:C within 50 ftGrounded per the CaliforniaElectrical CodeFuel check: 55 gal/h x 6 h = 330 gal minimum, kept in the tank at all times(55 gal/h is the example's given burn rate; the 6 h and "maintained at all times" are CFC text)Sources: 2025 CFC §1203.1.4, §1203.1.5, §1203.2, §1204; 8 CCR §2320.9CC
The diagram for this lesson, exactly as it appears in the Learning Hub.

The first steps of this lesson

Step 1: Emergency versus standby timing

2025 California Fire Code §1203.1.4: emergency power systems shall automatically provide secondary power within 10 seconds after primary power is lost, and standby power systems within 60 seconds, unless specified otherwise in the code. §1203.1.7 lets an emergency power system be used where a standby system is required. Stationary generators required by the code must be listed to UL 2200 (§1203.1.1) and are installed per the California Building Code, the California Electrical Code, NFPA 110 and NFPA 111 as referenced in §1203.1.3 (the referenced standards themselves are not part of this lesson).

Step 2: How long the power must last

§1203.1.5: emergency and standby systems must provide the required power for a minimum of 2 hours without refueling or recharging, unless specified otherwise. §1203.1.5.1: for high-rise buildings and Group I-2 occupancies with occupied floors more than 75 feet above the lowest level of building access, 6 hours, and the minimum required fuel supply shall be maintained at all times. Specific loads override the default: exit signs 90 minutes (§1203.2.6); mechanical exhaust ventilation 2 hours (§1203.2.5); emergency responder communication coverage 12 hours at 100 percent capacity (§1203.2.3); special purpose horizontal sliding doors enough capacity for not fewer than 50 closing cycles (§1203.2.12).

The remaining 3 steps, the worked example and the quiz are in the course. This is a preview. The full lesson, with the step-by-step explanations, a worked example and a quick-check quiz, is inside the classroom.

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