Lazy apprentice getting tested

Nearly there · Feb 2, 2011

Hi
basically Im a 2nd year apprentice and my boss wants to put me to the test
There is a commercial building thats single phase
The guy wants 2 temporary supplys for 2 seperate intruder alarms in one building
The run will be 100m
So far i have figured out (as yes i am lazy and i need to make a move)
I will be using 2 core SWA 4mm CLipped outside to an FCU which will be inside the building then spur off 2 x 2.5mm T+E 20metres to each side to the intruder alarms.
I will be using a 6A FCU
My boss wont help me untill i make a mistake and i just thought id ask for some help off the website ive been browsing
sorry for the basic questions =/

High Tower · Feb 2, 2011

1, volt drop calcs on a 100m run, do the calcs he may ask you for them as its a long run

telectrix · Feb 2, 2011

each alarm panel needs its own FCU at 3A mounted adjacent to the panel ( local isolation). your first FCU is feedin 2.5 cables so needs fusing at 13A. what protection are you using to protect the 4mm? volt drop won't be a problem as the panels pull a very small current, less than 1A. you could ask your boss what current the panels take. he probably won't have an idea without referring to the installation manual.

High Tower · Feb 2, 2011

Diddnt think it would be a big problem Tel, but it shows hes done his workings and its extracting this information from his boss, im just thinking about exceeding his bosses expectations here!

Sorry should have made what i ment clearer!!

telectrix · Feb 2, 2011

thats what i thought, see if he can put one over on his boss. bet his boss is expecting him to come straight off FCU and feed both alarms direct.

Sparky Ninja · Feb 2, 2011

what are the supply characteristics?
what is the primary and maybe secondary protective device?

simpson93 · Feb 2, 2011

i know this wont help you very much just abit of advice.
i would do what i think i would do and not ask for to much help as your boss is looking for what you know not the guys on the forum, if you do it correctly your boss may think your ready for much bigger things when you actually may not be. everyone makes mistakes its what you take away from your mistakes.

tony mc · Feb 2, 2011

I wonder if the Boss is on the forum or looks in occationally?

ian.settle1 · Feb 3, 2011

Hey lads don't take this the wrong way but your doing EXACTLY what his boss doesn't won't to do help him out until he makes a mistake, he won'ts hom to do it on his own and learn from his mistakes.

nickblake · Feb 3, 2011

this is true ian its the post title that rang alarm bells with me and weve all had them , all i can say is grab a copy of the regs look it up and maybe youll learn ,its not about getting the questions your boss asks right its the fact that you understand and learn and the only way you'll do that is to check the regs answer the questions , if you get it wrong then fine ,check the answer because you wont or shouldnt get it wrong the second time and then you'll learn ,and correct me if im wrong here but i dont think you find any Spark that appriciates a "lazy apprentice "

Nearly there · Feb 3, 2011

Ive decided to change the SWA to 2.5mm to save costs as the person whos place it is
wants minimum costs as it is a temporary supply
It will be protected by a 6A RCD or maybe an RCBO
I see where most of you are coming from that I need to learn
and i appreciate that fact
I jus wanted to get the pricing right aswell

Paul.M · Feb 3, 2011

If this is an all round exercise with costs taken into effect by your design, is it possible to run your 2.5mm inside and use t+e? Is there a cable tray already in the building you can use or is it the case that the boss wants you to use swa?

Nearly there · Feb 3, 2011

Well the first 100m run is from one building to another so i dont think ill be able to do it in T+E inside
But once I get to the first FCU the rest is internal so i can use T+E as there is metal trunking already laid there

High Tower · Feb 3, 2011

Well if as we suspect the panel will only pull about 3a step it right down to 1.5mm2 2 core SWA

Nearly there · Feb 3, 2011

High tower
I was thinking also about using 1.5mm
But its going to be spurred of to 2 panels
but there is only one intruder alarm
I asked my boss he said think about 4mm
going to a 13a FCU and 2 spurs straight to the panels

High Tower · Feb 3, 2011

Your boss says he thinks about 4mm that means he wants you to work it out, get the info on the panels, find out the rating and do your cable calcs and do them neetly so you can present them to him. Most panels only require about 3a so even 2 of them should only come to less than 10a, 1.5mm will carry way more than this.

13a spur at origin, fused down to 3a at the load.

Nearly there · Feb 4, 2011

I worked it out and decided to go with 2.5mm
He said ive got a surprise for me
We went to the warehouse and there was no mains board dist board or anything
Some gypsies stole everything even the main board so now I have to fit a small one
just for the intruder alarm
He told me to figure out what type of protection to use
Id jus think a normal 6a RCD protection will do