Discuss Calculating volt drop, cable selection and mcb selection on an 3kw motor in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

how the hell do i find a list of cb's/ select them from the OSG ????????? ...or have i just overworked my brain ????????? lol


Off the top of my head i don't think there is a list in the OSG - i always use appendix 3 of BS7671.

edit - oops table 7.1 seems to show them
 
Last edited by a moderator:
that q has really baffled me....Is the MCB ratings differnet when talking about 400v/ triple pole ? if so how do i find out which type to use and therefore do the resulting equations become affected ?
 
Much respect to you Widdler for putting so much time and effort in. One very small point which doesn't affect the outcome at all. The question said
So wouldn't that mean ref method B [42 from table 4A2?] not ref method C, so table 4D2A column 4 = 1.5mm² carries 16.5A

or am i wrong ?:)

Selected reference method was C (No. 57).

In questions where it states within building materials, it refers to direct in masonry. :)
It's all down to interpretation of reference methods, the syllabus I use have in this example gone with the above. But your opinion of reference method B can also be justified.
It's one of the biggest debates I have with my guys.
 
that q has really baffled me....Is the MCB ratings differnet when talking about 400v/ triple pole ? if so how do i find out which type to use and therefore do the resulting equations become affected ?

The question is answered with the exact same approach and formula bar one. The design current (Ib).

With Three phase (400V), we use the following formula:

Ib =
Power (P)
√3xUL
 
Selected reference method was C (No. 57).

In questions where it states within building materials, it refers to direct in masonry. :)
It's all down to interpretation of reference methods, the syllabus I use have in this example gone with the above. But your opinion of reference method B can also be justified.
It's one of the biggest debates I have with my guys.

Cheers for the reply, on reflection 57 is probs a better fit :)

I suppose we all have to carry our thermal resistivity meter in our kit as well ;)

Thanks for keeping my brain ticking over!
 
The question is answered with the exact same approach and formula bar one. The design current (Ib).

With Three phase (400V), we use the following formula:



Ib =
Power (P)



√3xUL
images


Not sure what other posters think but Widdler deserves that for this thread, it was good of you to help that lad out the way you did. Top man
 

Reply to Calculating volt drop, cable selection and mcb selection on an 3kw motor in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

Similar Threads

Hello, New trainee electrician so sorry if this is a dumb question I feel confident with calculating the volt drop for a ring and radial circuit...
Replies
2
Views
2K
I am trying to understand 3 phase volt drop. I understand single phase VD. Lets say we have a 70 meter run of 35mm, 5 core cable from the supply...
Replies
6
Views
2K
Hi everyone, I'm new here and was wondering if someone could help to get my college project calculations right. I'm about to start my 2nd year in...
Replies
12
Views
8K
  • Article
Electrical2Go - Electric Car Charging at Home - Comprehensive Guide As EV ownership and the transition towards electric cars rise, having a home...
Replies
0
Views
120
  • Locked
  • Sticky
Beware a little long. I served an electrical apprenticeship a long time ago, then went back to full time education immediately moving away from...
Replies
55
Views
5K

OFFICIAL SPONSORS

Electrical Goods - Electrical Tools - Brand Names Electrician Courses Green Electrical Goods PCB Way Electrical Goods - Electrical Tools - Brand Names Pushfit Wire Connectors Electric Underfloor Heating Electrician Courses
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc

YOUR Unread Posts

This website was designed, optimised and is hosted by untold.media Operating under the name Untold Media since 2001.
Back
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.

I've Disabled AdBlock