Safety — California C-10 Practice Questions

42 questions · 18% of the C-10 Electrical Trade exam

Worked questions

1. Before servicing equipment that may be energized from normal and standby sources, what must the worker do?

AOpen only the normal-source breaker
BRely on an indicator lamp
CBegin work after pressing the stop button
Isolate and verify every source

Why D is correct

Multiple sources can backfeed equipment. An electrically safe work condition requires source identification, isolation, lockout/tagout, and properly performed absence-of-voltage verification; controls and lamps are not isolating means.

2. Conduit installation occurs near an unprotected roof edge. What must be planned?

AWork only in rain
BTool belt as fall arrest
Fall protection, material control, access, and rescue
DA warning from ground

Why C is correct

Electrical roof work combines fall, lifting, weather, and electrical hazards. Protection must match the edge, task, anchors, travel, and rescue needs.

3. May an unqualified worker cross a restricted approach boundary alone?

AYes, with a hard hat only
BYes, for short tasks
No; access requires the applicable qualification and protective controls
DNo electrical boundary ever applies

Why C is correct

Approach boundaries limit shock exposure based on voltage and worker qualification. Duration and ordinary PPE do not replace training, authorization, and required protection.

4. An underground feeder trench is staked across an occupied industrial site. What must happen before excavation begins?

Locate utilities and establish the required excavation safety plan
BBegin digging and stop when a utility is seen
CUse only the electrical drawing as proof of location for the described C-10 installation and documented operating conditions
DPlace spoil at the trench edge

Why A is correct

The best answer is: Locate utilities and establish the required excavation safety plan. Utility locating and excavation planning prevent strikes, cave-ins, and unsafe access. Drawings may be incomplete, and spoil at the edge can add surcharge and fall back into the excavation. This transferred field condition tests the same installation or safety principle in a different project context. The other choices conflict with the cited rule, listing, safe-work process, or necessary diagnostic sequence.

5. Before measuring a 480-volt cabinet, what must be verified about the meter and accessories?

AThe meter is set to resistance on the energized circuit for the described C-10 installation and documented operating conditions
BThe meter display is the worker’s favorite color
The meter, leads, probes, and category rating are suitable and the meter is proven on a known source
DThe leads have exposed metal for easier contact

Why C is correct

The best answer is: The meter, leads, probes, and category rating are suitable and the meter is proven on a known source. A suitably rated, intact instrument and live-dead-live verification reduce the risk of false zero readings and meter failure. Exposed probes or resistance mode on an energized system can cause injury and equipment damage. This transferred field condition tests the same installation or safety principle in a different project context. The other choices conflict with the cited rule, listing, safe-work process, or necessary diagnostic sequence.

37 more in the bank

Answers and explanations for these are in the app.

A construction receptacle repeatedly trips its GFCI after rain. What is the proper response?
A damaged extension cord has exposed insulation at a construction site. What is the proper action?
A trench route crosses marked gas and electrical utilities. What should the crew do?
A worker needs to cross an established arc-flash boundary for justified energized work. What is required?
An aluminum ladder is proposed beside exposed energized parts. What should change?
An electrical vault may contain atmospheric hazards and limited entry. What should occur before entry?
An underground electrical vault may contain gas and has limited entry. What is required?
Before trenching for an underground electrical raceway, what is the first essential field control?
Conduit brazing is planned near combustible construction. What controls are needed?
Dry drilling for anchors creates a visible silica cloud. What should occur?
Equipment has utility, generator, and control-power sources. What must lockout cover?
Equipment labels are missing and an energized task is proposed. What should occur?
Power-factor-correction capacitors have been disconnected. Why must they still be treated cautiously?
What must be confirmed before using a meter on a 480-volt system?
Which ladder is appropriate where accidental contact with energized parts is possible?
Why are insulated tools and removal of conductive jewelry important around battery systems?
Why is a tester proven before and after an absence-of-voltage test?
Why must jewelry be removed around battery terminals?
A below-grade vault may contain hazardous gas and has restricted entry. Which program governs entry?
A portable ladder will be used near exposed energized parts. Which ladder and work controls are appropriate?
A ring bridges two battery terminals during maintenance. Why can severe injury occur even on a modest-voltage system?
A technician wears a metal watch while servicing a battery bank. Why should conductive jewelry and uninsulated tools be removed?
A temporary-power cord has a cut jacket and visible insulation damage. What should the foreman do with it?
After rain, a temporary receptacle repeatedly trips its GFCI. What should happen before it is returned to service?
An aluminum extension ladder is selected for work beside exposed live conductors. What should be changed?
An apprentice without electrical qualification is asked to cross a restricted approach boundary alone. Is that permitted?
An automatic transfer system can energize equipment from both utility and generator sources. What must the lockout plan cover?
An enclosure receives utility, generator, UPS control, and stored-energy inputs. Which sources must the LOTO procedure address?
An excavation crosses tolerance zones for marked gas and electrical utilities. Which locating and exposure practices apply?
An underground electrical room has limited access and possible atmospheric contamination. What must precede entry?
Arc-flash labels are unavailable for proposed energized diagnostics. What must occur before PPE is selected?
Brazing conduit supports near combustible finish creates sparks and heat. Which permits, shielding, and watch controls are needed?
Capacitor equipment has been disconnected for service. Why is absence-of-voltage verification still necessary?
Dry anchor drilling produces a visible silica plume around electrical installers. What exposure controls are required?
Justified energized work will cross an arc-flash boundary. Which controls are required before the worker enters it?
Raceway is being installed within fall exposure of an unprotected roof edge. Which controls must be planned?
Why should a voltage tester be checked on a known energized source both before and after verifying de-energization?

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Safety — California C-10 Practice Questions

Worked questions

1. Before servicing equipment that may be energized from normal and standby sources, what must the worker do?

2. Conduit installation occurs near an unprotected roof edge. What must be planned?

3. May an unqualified worker cross a restricted approach boundary alone?

4. An underground feeder trench is staked across an occupied industrial site. What must happen before excavation begins?

5. Before measuring a 480-volt cabinet, what must be verified about the meter and accessories?

37 more in the bank

Other California C-10 content areas