2391-52 exam question

[Phillip]

The answer must be lower than 20. Which only leaves 13. This should have only taken about one nano second to answer.

 

[w0z]

Hello,
Would anyone be able to help with this question I do not seem to have the knowledge to answer please?

44
Questions 40 to 46 relate to the following scenario.
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.

Circuit Line-line ohms Line-earth ohms
1 190 176
2 187 20
3 157 162
4 122 134
5 172 178

Initial and Periodic Inspection and Testing of Electrical Installations (2391-052)
Sample Questions
17What 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

Response: correct answer is (a) I said (c)

Thanks in advance hope Duncan

Is the second part of the question How big is the bang if it's really ohms?