Bear
-
- Reaction score
- 30
Afternoon all,
How do i solve these two questions, Feel like am missing something simple. doing my head in lol.
I need to learn the calculation for them both, I am struggling to work it out.
1.
Insulation resistance has been tested on five new lighting circuits in an existing large distribution warehouse. These circuits are supplied from a new single-phase, five-way DB.
Switching for each circuit is by 230 V contactors. Connection to each light is made using a
BS 1363 socket-outlet adjacent to the fitting.
The supply and installation form a 400 V three-phase TN-C-S system. The following test results were recorded.
What is the value of insulation resistance between Live and Earth for the new DB with all the lighting circuits connected?
a) 13 MΩ
b) 20 MΩ
c) 134 MΩ
d) 178 MΩ
2.
Continuity of a ring final circuit has been tested as part of an initial verification of a new primary school. All the socket-outlets are connected directly to the ring.
The circuit loop length is 58 m long, wired in 4 mm2 live and 1.5 mm2 cpc flat profile cable. The circuit is protected by a 32 A BS EN 60898 Type B circuit breaker.
What is the expected measured value at each socket-outlet when the line and neutral conductors are correctly cross-connected?
a) 0.13 Ω
b) 0.16 Ω
c) 0.22 Ω
d) 0.49 Ω
How do i solve these two questions, Feel like am missing something simple. doing my head in lol.
I need to learn the calculation for them both, I am struggling to work it out.
1.
Insulation resistance has been tested on five new lighting circuits in an existing large distribution warehouse. These circuits are supplied from a new single-phase, five-way DB.
Switching for each circuit is by 230 V contactors. Connection to each light is made using a
BS 1363 socket-outlet adjacent to the fitting.
The supply and installation form a 400 V three-phase TN-C-S system. The following test results were recorded.
What is the value of insulation resistance between Live and Earth for the new DB with all the lighting circuits connected?
a) 13 MΩ
b) 20 MΩ
c) 134 MΩ
d) 178 MΩ
2.
Continuity of a ring final circuit has been tested as part of an initial verification of a new primary school. All the socket-outlets are connected directly to the ring.
The circuit loop length is 58 m long, wired in 4 mm2 live and 1.5 mm2 cpc flat profile cable. The circuit is protected by a 32 A BS EN 60898 Type B circuit breaker.
What is the expected measured value at each socket-outlet when the line and neutral conductors are correctly cross-connected?
a) 0.13 Ω
b) 0.16 Ω
c) 0.22 Ω
d) 0.49 Ω