Substation Electrician Apprenticeship Exam Questions with Correct Answers Latest Update
2025/2026
Please list the 6 major categories of discussion for any tailboard. - Answers a. Methods of
emergency notification
b. What is our job plan?
c. What is energized? What is not? What are the clearance points?
d. What are the hazards associated with the job?
e. What are the assignments, groups or individuals?
Special precautions, special equipment, PPE?
g. Does everyone understand/ask questions?
What are the major categories of a Substation Maintenance switching tailboard? - Answers a.
Methods of emergency notifications
b. What is our switching assignment?
c. How will we accomplish the switching?
d. Have I verified equipment to be operational?
e. What are the hazards involved/ PPE required?
f. What are my clearance points?
g. Are grounds installed? If so, where?
What are the basic safe work practices observed in a 230KV or 500KV receiving station? -
Answers Check in to station upon arrival, close and lock gate after entering. Maintain MAD for
personnel and equipment as well as safe working clearances at all times 500KV- PTG
11'11"PTP 19'9"230KV- PTG 5'8"PTP 9'2"115KV- PTG 3'4" PTP 4'7" 69KV- PTG 2'11" PTP 3'9"
PWalk down yard and visually inspect for damaged equipment or missing/broken
grounds.tailboard with other crews in working in the same area. Maintain speed limits and
follow roadways.
What insulating mediums are used in EHV breakers? - Answers SF6 gas, ultra-dry high pressure
air, polymer, ceramics, air, epoxy, silicone
What does a WIKA gauge measure? - Answers WIKA is a brand. Usually, it is measuring gas
pressure.
What is the minimum % of gas density that SRP allows in an EHV breaker? - Answers 98% on all
, new breakers,98% on Palo Verde Breakers, 97% on all other voltage class breakers including
older 500KV breakers.
Is SF6 gas harmful and or a hazardous material? - Answers Yes, it displaces oxygen and can
create a toxic substance when used to suppress an electric arc. It is invisible, odorless, and
tasteless.
Explain the difference between a live tank and a dead tank breaker. - Answers A live Tank
breaker has external energized tanks that are isolated from ground. These tanks contain the
interrupting contacts, which are above ground potential.
A dead tank breaker has their interrupting contacts enclosed in tanks that are at ground
potential.
What type of EHV breaker has a free standing C.T.? - Answers A live tank breaker.
Preventative breaker maintenance consists of what? - Answers Tailboard and be working under
a grounded clearance. Power factor test, ductor/micro-ohm test (the resistance of closed
contacts, timing test ( opening and closing) , checking moisture, purity and density of SF6 gas
(and content of SO2 if any), pressure switch settings, service the compressors (oil change and
belt checks, pump times), check heaters, mechanism travel measurements, alarm checks ( low
gas and low gas lock outs, motor trouble/fail) , and an inspection of the overall condition of the
breaker.
Name the different types of operating mechanisms and explain the safety hazards associated
with each. - Answers Air Hazards include: pressurized containment vessel, air leaks are not
visible, fittings, hoses, regulators and air tools need to be rated for the pressure to be applied,
beware of moving parts, drain air pressure before performing maintenance.
Hydraulic hazards: pressurized containment vessel, containment vessel has a nitrogen pre-
charge pressure even after hydraulic pressure has been drained, hydraulic oil is flammable,
beware of moving parts, drain hydraulic pressure before performing maintenance.
Spring hazards: beware of moving parts, discharge spring pressure before performing
maintenance, spring can be charged in both open and closed breaker positions.
Describe the basic function of the SF6 trailer has? - Answers It is used to evacuate, purify, store,
consolidate and fill SF6 gas.
How does an SF6 gas breaker quench an arc? - Answers Current interruption in a high-voltage
2025/2026
Please list the 6 major categories of discussion for any tailboard. - Answers a. Methods of
emergency notification
b. What is our job plan?
c. What is energized? What is not? What are the clearance points?
d. What are the hazards associated with the job?
e. What are the assignments, groups or individuals?
Special precautions, special equipment, PPE?
g. Does everyone understand/ask questions?
What are the major categories of a Substation Maintenance switching tailboard? - Answers a.
Methods of emergency notifications
b. What is our switching assignment?
c. How will we accomplish the switching?
d. Have I verified equipment to be operational?
e. What are the hazards involved/ PPE required?
f. What are my clearance points?
g. Are grounds installed? If so, where?
What are the basic safe work practices observed in a 230KV or 500KV receiving station? -
Answers Check in to station upon arrival, close and lock gate after entering. Maintain MAD for
personnel and equipment as well as safe working clearances at all times 500KV- PTG
11'11"PTP 19'9"230KV- PTG 5'8"PTP 9'2"115KV- PTG 3'4" PTP 4'7" 69KV- PTG 2'11" PTP 3'9"
PWalk down yard and visually inspect for damaged equipment or missing/broken
grounds.tailboard with other crews in working in the same area. Maintain speed limits and
follow roadways.
What insulating mediums are used in EHV breakers? - Answers SF6 gas, ultra-dry high pressure
air, polymer, ceramics, air, epoxy, silicone
What does a WIKA gauge measure? - Answers WIKA is a brand. Usually, it is measuring gas
pressure.
What is the minimum % of gas density that SRP allows in an EHV breaker? - Answers 98% on all
, new breakers,98% on Palo Verde Breakers, 97% on all other voltage class breakers including
older 500KV breakers.
Is SF6 gas harmful and or a hazardous material? - Answers Yes, it displaces oxygen and can
create a toxic substance when used to suppress an electric arc. It is invisible, odorless, and
tasteless.
Explain the difference between a live tank and a dead tank breaker. - Answers A live Tank
breaker has external energized tanks that are isolated from ground. These tanks contain the
interrupting contacts, which are above ground potential.
A dead tank breaker has their interrupting contacts enclosed in tanks that are at ground
potential.
What type of EHV breaker has a free standing C.T.? - Answers A live tank breaker.
Preventative breaker maintenance consists of what? - Answers Tailboard and be working under
a grounded clearance. Power factor test, ductor/micro-ohm test (the resistance of closed
contacts, timing test ( opening and closing) , checking moisture, purity and density of SF6 gas
(and content of SO2 if any), pressure switch settings, service the compressors (oil change and
belt checks, pump times), check heaters, mechanism travel measurements, alarm checks ( low
gas and low gas lock outs, motor trouble/fail) , and an inspection of the overall condition of the
breaker.
Name the different types of operating mechanisms and explain the safety hazards associated
with each. - Answers Air Hazards include: pressurized containment vessel, air leaks are not
visible, fittings, hoses, regulators and air tools need to be rated for the pressure to be applied,
beware of moving parts, drain air pressure before performing maintenance.
Hydraulic hazards: pressurized containment vessel, containment vessel has a nitrogen pre-
charge pressure even after hydraulic pressure has been drained, hydraulic oil is flammable,
beware of moving parts, drain hydraulic pressure before performing maintenance.
Spring hazards: beware of moving parts, discharge spring pressure before performing
maintenance, spring can be charged in both open and closed breaker positions.
Describe the basic function of the SF6 trailer has? - Answers It is used to evacuate, purify, store,
consolidate and fill SF6 gas.
How does an SF6 gas breaker quench an arc? - Answers Current interruption in a high-voltage
