Electrical Installation LEVEL 3
EXAM STUDY GUIDE 2026/2027
COMPLETE QUESTIONS WITH
VERIFIED CORRECT ANSWERS ||
100% GUARANTEED PASS
<NEWEST VERSION>
1. What is the voltage for generation? - ANSWER ✔ 25kV
2. What is transmission voltage? - ANSWER ✔ 275kV and 400kV (Super grid
transmission)
132kV (Original grid transmission)
3. Why is alternating current preferred over direct current? - ANSWER ✔ AC
transformers can be used to step up voltages for transmission and
distribution, reducing current and hence volt drop.
This will result in cables with a smaller cross sectional area reducing costs.
At the point at utilisation the voltage is stepped down to a safer voltage. This
cannot be done with DC.
,4. What are the distribution voltages? - ANSWER ✔ 132kv
66kv
33kV (distribution)
11kV (area distribution) delta
400/230 (local distribution)
5. What are the 3 AC electrical loads? - ANSWER ✔ Resistance - heating
elements or water heating elements
Inductor - inductive loads involves magnetism such as motors, ballast unit,
fluorescent luminaries
Capacitor - fitted to loads to improve power factor
6. In induction what leads and lags? - ANSWER ✔ Current lags and voltage
leads
7. What's leads and lags in a capacitor? - ANSWER ✔ Current leading voltage
lags
8. What is true power? - ANSWER ✔ Measured in kW
Is the rating of the load before power factor is considered.
9. What is apparent power? - ANSWER ✔ Measured in kVa
, Represents the angle of lead or lag
10.What is reactive power? - ANSWER ✔ Measured in kVar
Is the actual current voltage drawn. The greater the angle of lead the greater
the reactance.
Power loss due to reactance
11.Name two Competent person schemes in the Electrical industry. - ANSWER
✔ NICEIC, NAPIT, ELECSA, STROMA
12.State 3 reasons for possible delays to an agreed contract. - ANSWER ✔
Delays from other trades, employee shortages, delayed arrival of
materials/tools, Weather conditions.
13.What are the 3 main earthing systems used in the UK, and what are their
respective 'Ze' values? - ANSWER ✔ TN-S (Ze: 0.8), TN-C-S (Ze: 0.35),
TT (Ze: 21)
14.What does 'PME' stand for and what earthing arrangement is it commonly
referred to as? - ANSWER ✔ Protective Main Earthing, TN-C-S
15.List 3 examples of energy sources that are NOT fossil fuels. - ANSWER ✔ -
Nuclear
- Solar
- Hydro
- Wave / Tidal
- Wind
, 16.What are the 2 Three-phase configurations? - ANSWER ✔ - Delta:
Transformers that step up/down electricity are wired in a Delta
configuration.
- Star: The output of the sub-station transformer is wired in a Star
configuration.
17.Explain the purpose of a Circuit Breaker. - ANSWER ✔ Protects against
Overcurrent/Overloads and Short-circuits.
18.Explain the purpose of an RCD. - ANSWER ✔ Protects against Earth faults.
19.Explain the purpose of an RCBO. - ANSWER ✔ Provides Circuit Breaker
and RCD protection, all in one device.
20.A type 'C' Circuit Breaker will disconnect how many times the rated current?
- ANSWER ✔ 10 times.
21.A type 'B' Circuit Breaker will disconnect how many times the rated current?
- ANSWER ✔ 5 times.
22.A type 'D' Circuit Breaker will disconnect how many times the rated
current? - ANSWER ✔ 20 times.
23.Define 'ICN'. - ANSWER ✔ Rated Breaking Capacity.
EXAM STUDY GUIDE 2026/2027
COMPLETE QUESTIONS WITH
VERIFIED CORRECT ANSWERS ||
100% GUARANTEED PASS
<NEWEST VERSION>
1. What is the voltage for generation? - ANSWER ✔ 25kV
2. What is transmission voltage? - ANSWER ✔ 275kV and 400kV (Super grid
transmission)
132kV (Original grid transmission)
3. Why is alternating current preferred over direct current? - ANSWER ✔ AC
transformers can be used to step up voltages for transmission and
distribution, reducing current and hence volt drop.
This will result in cables with a smaller cross sectional area reducing costs.
At the point at utilisation the voltage is stepped down to a safer voltage. This
cannot be done with DC.
,4. What are the distribution voltages? - ANSWER ✔ 132kv
66kv
33kV (distribution)
11kV (area distribution) delta
400/230 (local distribution)
5. What are the 3 AC electrical loads? - ANSWER ✔ Resistance - heating
elements or water heating elements
Inductor - inductive loads involves magnetism such as motors, ballast unit,
fluorescent luminaries
Capacitor - fitted to loads to improve power factor
6. In induction what leads and lags? - ANSWER ✔ Current lags and voltage
leads
7. What's leads and lags in a capacitor? - ANSWER ✔ Current leading voltage
lags
8. What is true power? - ANSWER ✔ Measured in kW
Is the rating of the load before power factor is considered.
9. What is apparent power? - ANSWER ✔ Measured in kVa
, Represents the angle of lead or lag
10.What is reactive power? - ANSWER ✔ Measured in kVar
Is the actual current voltage drawn. The greater the angle of lead the greater
the reactance.
Power loss due to reactance
11.Name two Competent person schemes in the Electrical industry. - ANSWER
✔ NICEIC, NAPIT, ELECSA, STROMA
12.State 3 reasons for possible delays to an agreed contract. - ANSWER ✔
Delays from other trades, employee shortages, delayed arrival of
materials/tools, Weather conditions.
13.What are the 3 main earthing systems used in the UK, and what are their
respective 'Ze' values? - ANSWER ✔ TN-S (Ze: 0.8), TN-C-S (Ze: 0.35),
TT (Ze: 21)
14.What does 'PME' stand for and what earthing arrangement is it commonly
referred to as? - ANSWER ✔ Protective Main Earthing, TN-C-S
15.List 3 examples of energy sources that are NOT fossil fuels. - ANSWER ✔ -
Nuclear
- Solar
- Hydro
- Wave / Tidal
- Wind
, 16.What are the 2 Three-phase configurations? - ANSWER ✔ - Delta:
Transformers that step up/down electricity are wired in a Delta
configuration.
- Star: The output of the sub-station transformer is wired in a Star
configuration.
17.Explain the purpose of a Circuit Breaker. - ANSWER ✔ Protects against
Overcurrent/Overloads and Short-circuits.
18.Explain the purpose of an RCD. - ANSWER ✔ Protects against Earth faults.
19.Explain the purpose of an RCBO. - ANSWER ✔ Provides Circuit Breaker
and RCD protection, all in one device.
20.A type 'C' Circuit Breaker will disconnect how many times the rated current?
- ANSWER ✔ 10 times.
21.A type 'B' Circuit Breaker will disconnect how many times the rated current?
- ANSWER ✔ 5 times.
22.A type 'D' Circuit Breaker will disconnect how many times the rated
current? - ANSWER ✔ 20 times.
23.Define 'ICN'. - ANSWER ✔ Rated Breaking Capacity.
