voltage drop in a circuit

[NozSpark]

Well maybe they want you to design the circuit fully.. and not just calculate the voltage drop..

 

[Andy™]

then wouldnt it say that?

but still no enough info for that. i.e can it be T&E. does it need to be SWA or pyro to avoid RCD's etc etc

 

[SPECIAL LOCATION]

the question i put on was of a collage paper.it does not say what cable to use.collage lecturers. why don't they just make it easy then try`ing to confuse. a--- holes

they don't try to confuse you searley...

its just common exam technique to try and find if you have genuinely understood the concepts taught..

you can train monkeys & parrots to do repetitive tasks of the same thing over & over...

but you need to start thinking how can I work the question backwards or sideways to the way I was taught?

The fact that it says buried IMHO probably means it is PVC T&E..

you don't very often bury Pyro? in the building fabric.

They want you to look at the evidence and make a reasonable assumption..

a 3kw load is supplied from a 230v, 50hz supply.

e.g. MAYBE SINGLE PHASE ?

the circuit is protected using bs 3036 (rewirable) fuse and is situated 15m away from the db .

e.g. MAYBE TYPICAL DOMESTIC USE FUSE & DISTANCE?

it is run with one other circuit and is buried within the buliding material of the intallation.

e.g. MAYBE T&E IN PLASTER WITH A SOCKET CIRCUIT?

the temp within the installation can be assumed to be 25c.determine the volt drop ?

e.g. NOT A HOT FACTORY ENVIRONMENT REQUIRING HEAT RESISTANT CABLE SUCH AS PYRO?

making a few reasonable assumptions from the details given I would be guessing on a domestic T&E run!!

Commercial probably run with multiple other circuits on a tray or surface wall or something etc...

But then I could of course have me bra on backwards AND upside down!!Blushing:O

 

[SPECIAL LOCATION]

dont think VD tables are in OSG. you need the regs for that. there are a few pages with VD for various cables

The volt drops in the On Site Guide pages 133 & 134

are for PVC copper cables (e.g your typical domestic / light commercial use)

As Noz said full info in Appendix 4 of the big-un!!!

 

[Apache]

I get you upto the point you magically decide it's 6mm T&E. Why not 2.5mm 4mm etc?

 

[SPECIAL LOCATION]

BS7671 pages 274-317 cover cable VD (did I get this before Special Applaud Smiley)

In the words of that dog on the car insurance ads..

Oh YES YES YES!!!

Applaud SmileyApplaud SmileyApplaud SmileyApplaud Smiley

well done Robojin..

I think you can go and grab a prize of Admins top shelf for that:x

But don't take his Twix!! he don't like letting them go!!!

Guiness DrinkGuiness DrinkGuiness Drink

I obviously spent too long in the loo putting me pants straight before I logged on!Blushing

 

[NozSpark]

As patch says,

I think that this question is aimed at you designing the circuit..

You can calculate the load,

you know the distance

you know the installation method

you know the applicable correction factors

you know the type of protective device

You should go through the calcs going up from the smallest cable size for the load 1.5/1.0, 2.5/1.5, 4.0/2.5 and possibly higher until you get a cable size which passes all the calculations

 

[SPECIAL LOCATION]

I get you upto the point you magically decide it's 6mm T&E. Why not 2.5mm 4mm etc?

Well done oh wise and wonderful vet'ish type man!!!Blushing:x:x

The beer has flowed... and has been swallowed...

and is still flowing!!!Guiness DrinkGuiness DrinkGuiness Drink

now somewhere.......

although looking back I cant see where??????:_|Blushing:|

I thought I read the word Cooker???? Doh!!!!!!

I shall go and sit quietly with me bag of crisps and me beer and stay out of trouble!!!! :_| :_|