Electrical project for level 3

Lukaszbjj · Dec 31, 2022

Hi, Im in the process of doing my level 3 project for the hotel extension and Cafe pool so please check the attached screenshots maybe someone can explain to me what should I put in these 2 columns? They are really confusing to me as my calculation for IT was " it = in / Ca x Cg " but they want also in / Ca x Cg which would be THE SAME ?

jaffa183 · Dec 31, 2022

"it" is the rated value of your cable selection as in its max current.

Lukaszbjj · Dec 31, 2022

jaffa183 said:
"it" is the rated value of your cable selection as in its max current.

Do you know which table in ONS or Regs book I can find it?

Lukaszbjj · Dec 31, 2022

Lukaszbjj said:
Do you know which table in ONS or Regs book I can find it?

Okay, I found it but how do I know which method to choose? All my calculations are with Ref Method B and C but there is no Reference Method B in that table?

jaffa183 · Dec 31, 2022

Lukaszbjj said:
Do you know which table in ONS or Regs book I can find it?

In the OSG(Brown Book) it is in appendix F page 171 and the regs book(Brown Book) it starts at page 448 table 4D1A Ive attached how i did mine if thats any help.

jaffa183 · Dec 31, 2022

Lukaszbjj said:
Okay, I found it but how do I know which method to choose? All my calculations are with Ref Method B and C but there is no Reference Method B in that table?

it says it at top of table see picture

buzzlightyear · Dec 31, 2022

Look in the back of the big brown. And it will show you methods with cable it is.

Lukaszbjj · Dec 31, 2022

jaffa183 said:
it says it at top of table see picture

Thank you much appreciated.

Lukaszbjj · Jan 1, 2023

Lukaszbjj said:
Okay, I found it but how do I know which method to choose? All my calculations are with Ref Method B and C but there is no Reference Method B in that table?

I've done all the "hard" work with calculations and thought these last 2 questions will be easy but I was so wrong. Does anyone know where can I possibly find information about these two questions?

jaffa183 · Jan 1, 2023

Lukaszbjj said:
I've done all the "hard" work with calculations and thought these last 2 questions will be easy but I was so wrong. Does anyone know where can I possibly find information about these two questions?

If you look at the definitions in BS7671 that will help answer the question, ive attached an example of how i did mine.