Designing and calculating

magnoliafan89 · Nov 1, 2018

Hi guys

I asked my work to help me wrap my head around calculating and designing for cable sizes. I watched chris kitcher on poo tube to get a better grip. My manager posed a scenario and ive tried calculating it but it doesnt seem right.

This is the set up.

There is an outbuilding 45m away that will have sockets and lights. Expect usage to be about 3kw.
It will be run underground but just buried no additional protection.

So i started with design current
Ib=p/v=3000/230 equals 13.04A

Protective device range
IN= 16A

Rating factor for ambient temp is roughly 30 degrees so this is equal to 1.00.
It greater than or equal to IN over rating factor equals 16/1.00 =16A

Reference method D so in table 4E4A to find anything near 16a means itll only be a 1.5mm conductor size.....

Where have i gone wrong??

Silly Sausage · Nov 1, 2018

What's the voltage drop on 45m @ 13A?

Squid · Nov 1, 2018

Archy Styrigg said:
What's the voltage drop on 45m @ 13A?

Depends on the scenario.

Nigel · Nov 1, 2018

Are you a trainee?

Spoon · Nov 1, 2018

Double check the table you are using as well...

magnoliafan89 · Nov 1, 2018

Thanks for the responses guys.
Yeh still a trainee. Passed my am2 3 weeks ago just finishing off my portfolio and told my employer id like to know how to design circuit and do all the calculations instead of just being told what to use as i want to learn as much as possible.

MFS Electrical · Nov 1, 2018

magnoliafan89 said:
Thanks for the responses guys.
Yeh still a trainee. Passed my am2 3 weeks ago just finishing off my portfolio and told my employer id like to know how to design circuit and do all the calculations instead of just being told what to use as i want to learn as much as possible.

You should get yourself into the trainee area

Pete999 · Nov 1, 2018

magnoliafan89 said:
Hi guys

I asked my work to help me wrap my head around calculating and designing for cable sizes. I watched chris kitcher on poo tube to get a better grip. My manager posed a scenario and ive tried calculating it but it doesnt seem right.

This is the set up.

There is an outbuilding 45m away that will have sockets and lights. Expect usage to be about 3kw.
It will be run underground but just buried no additional protection.

So i started with design current
Ib=p/v=3000/230 equals 13.04A

Protective device range
IN= 16A

Rating factor for ambient temp is roughly 30 degrees so this is equal to 1.00.
It greater than or equal to IN over rating factor equals 16/1.00 =16A

Reference method D so in table 4E4A to find anything near 16a means itll only be a 1.5mm conductor size.....

Where have i gone wrong??

A good video to get you started, there are plenty more, but this Bloke is one of the best, imo

Loki · Nov 1, 2018

magnoliafan89 said:
Hi guys

I asked my work to help me wrap my head around calculating and designing for cable sizes. I watched chris kitcher on poo tube to get a better grip. My manager posed a scenario and ive tried calculating it but it doesnt seem right.

This is the set up.

There is an outbuilding 45m away that will have sockets and lights. Expect usage to be about 3kw.
It will be run underground but just buried no additional protection.

So i started with design current
Ib=p/v=3000/230 equals 13.04A

Protective device range
IN= 16A

Rating factor for ambient temp is roughly 30 degrees so this is equal to 1.00.
It greater than or equal to IN over rating factor equals 16/1.00 =16A

Reference method D so in table 4E4A to find anything near 16a means itll only be a 1.5mm conductor size.....

Where have i gone wrong??

Hi,

Im currently doing the 104 assignment for the hotel, cafe & pool.

Got this from my training provider which might help:

[ElectriciansForums.net] Designing and calculating

Spoon · Nov 1, 2018

As no one has commented "Spoon, not only are you stunningly good looking but your observation skills are second to none.." on my post #5, I thought I'd better expand on it....
Check out reg 512.1.5

magnoliafan89 · Nov 1, 2018

Pete999 said:
A good video to get you started, there are plenty more, but this Bloke is one of the best, imo

Funnily enough this was the video i was watching. I wrote out what he qas doing as he was doing it understood it....until i had to do it for a different scenario

Haroon · May 26, 2019

Loki said:
Hi,

Im currently doing the 104 assignment for the hotel, cafe & pool.

Got this from my training provider which might help:

View attachment 45394

Have anyone done Q6 of design assignment