Planning & Estimating — California C-10 Practice Questions

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Answers and explanations for these are in the app.

• A 120-volt circuit is expected to drop 6 volts at design load. What percent voltage drop is that?
• A 15-kVA single-phase transformer has a 240-volt secondary. What is the full-load secondary current?
• A 240-volt single-phase generator is rated 18 kVA. Using I = VA ÷ V, what rated current corresponds to that output?
• A 240-volt single-phase resistive load draws 18 amperes. What is its power?
• A 32-amp load is expected to operate continuously. Ignoring any special listed assembly, what minimum branch-circuit ampacity is required?
• A balanced 480-volt three-phase load draws 30 amperes at unity power factor. Approximately how much real power does it use?
• A battery has 12 kWh of usable energy and supplies a steady 3 kW load. Ignoring conversion losses, how long can it support the load?
• A battery system is planned inside an occupied building. What should the estimate coordinate?
• A crew of two electricians is scheduled for three 8-hour days. How many labor-hours should the estimate carry?
• A design relies on an energy-management system to avoid a service upgrade for EV charging. What should be verified?
• A dry-type transformer is added in a small electrical room. What scope must be coordinated?
• A job needs 240 feet of raceway. The estimator adds 8 percent for waste and field changes. How many feet should be carried before rounding to purchasable lengths?
• A long branch circuit meets minimum ampacity but calculated voltage drop is excessive. What is the appropriate design response?
• A new service requires utility transformer and meter work. What should be coordinated early?
• A plan lists motor horsepower but not the information needed for final branch-circuit selection. What should be obtained?
• A project needs 375 feet of cable and carries 6 percent waste. What quantity results before purchase-length rounding?
• A proposed device box will contain four insulated conductors, equipment grounds, an internal clamp, and one device yoke. How should the estimator verify box size?
• A PV inverter is added to an existing panel. What must be reviewed at the connection point?
• A renovation adds commercial cooking equipment to an existing service. What must be established before pricing breaker additions?
• A rooftop PV project is being estimated. Which value is essential when checking the maximum DC system voltage?
• A room layout places permanent shelving in front of a panelboard. What should occur before final pricing?
• A route has multiple bends and congested pull points. What belongs in the takeoff?
• A single-phase PV inverter delivers 7.2 kW at 240 volts at the stated operating point. Using I = P ÷ V, what output current does that represent?
• A standby generator serves motor and nonmotor loads. What must the estimate consider?
• An existing panel has two spare spaces. Before adding a 48-amp EV charging load, what must the contractor determine first?
• Before pricing additional conductors in an existing raceway, which information is necessary for a defensible fill calculation?
• Plans specify mounting listed equipment in an orientation prohibited by its instructions. What should the contractor carry in the estimate?
• The available fault current at a new switchboard is greater than the marked interrupting rating of its main breaker. What must change?
• The electrical drawings and specifications assign firestopping around penetrations to different trades. What is the best bid response?
• A 120-volt branch circuit is calculated to lose 4.8 volts at design load. What is the voltage-drop percentage?
• A 2026 permit project omits required lighting controls and acceptance testing from the drawings. What should the electrical bid carry?
• A 240-volt single-phase heater draws 22 amperes. How much power does it consume?
• A conduit route accumulates difficult bends before reaching the next accessible enclosure. What should the takeoff add?
• A generator will start a large motor while supplying selected lighting and controls. Which loads and operating sequence govern sizing?
• A listed PV inverter will connect to an existing bus. What must be checked at the proposed interconnection point?
• A pull box contains conductors, grounding conductors, an internal clamp, and a device yoke. How should its required volume be established?
• A remote 120-volt pump circuit has acceptable ampacity but unacceptable voltage drop at startup. Which design change is appropriate?
• A restaurant remodel adds ovens and refrigeration to an older service. What must estimating establish before treating spare breaker spaces as usable capacity?
• A takeoff contains 325 feet of conduit and a 7% waste allowance. What quantity should be carried before purchase-length rounding?
• A tenant improvement adds a 48-ampere continuous EVSE to an older distribution system. What must be confirmed before a breaker is selected?
• A transformer is squeezed into a storage room with little airflow and obstructed access. Which coordinated scope must be included?
• An electric boiler draws 28 amperes for more than three hours. What minimum branch-circuit ampacity is required under the general 125% rule?
• An estimate requires 460 feet of cable plus a 5% installation allowance. What quantity results before reel-length rounding?
• An estimator wants to add a circuit to a partly occupied conduit. Which complete set of data is needed to check fill?
• An EV energy-management system is used to cap building demand. What qualification must be verified before relying on it in the load calculation?
• Clamp readings on a unity-power-factor three-phase test bank are 35 amperes per line, and the measured line voltage is 208 volts. What approximate input should appear on the power record?
• Commissioning measurements show 480 volts line-to-line and 25 amperes on each phase of a resistive three-phase bank. Estimate its input kilowatts using the three-phase vector factor.
• Door release, smoke control, and air-handler shutdown depend on the fire alarm. What must the electrical scope coordinate?
• During acceptance testing, an electrician must set the expected secondary-current benchmark for a 25-kVA single-phase unit delivering 240 volts. What value should be recorded?
• Five electricians each work three 8-hour shifts. How many labor-hours should be budgeted?
• Four electricians are scheduled for two 9-hour shifts. How many labor-hours belong in the estimate?
• Only horsepower appears on a motor schedule. Which additional data is needed to complete branch-circuit and starting design?
• The architectural and electrical documents disagree about who seals rated penetrations. What should the C-10 bidder do?
• The only available mounting position conflicts with the listed switchboard instructions. What should the bid include?
• The riser diagram and equipment schedule specify different feeder conductors. What is the proper estimating response?
• The utility revises available fault-current data above the value used for procurement. What needs to be reevaluated?
• Utility data shows 50 kA available at equipment whose main device is marked 35 kA. What must the design team correct before installation?

Other California C-10 content areas

• Business Organization & Licensing30 questions
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• Contract Requirements & Execution48 questions
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