Please help!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[mick78]

please help i have been given a piece of coursework to complete. it involves doing an electrical install on a 6 bed country house with 2 floors with a total floor space of 170 sq m on each floor.

i am completely new to this whole concept.
from what i have read so far i have to do this in stages like finding design current Ib etc.

do i have to use 2 ring mains for downstairs sockets because of floor space? as well as separate ring for kitchen.

do i have to do the same for lights?

i was trying to work out design current by adding up all loads eg, 2000W for hoover, 300W for television etc is this correct?

but have also found that ring circuits have to be 32A is this correct.?

do i apply diversity to the 32A or the summation of all loads?

lecturer has let slip that house is supplied single phase. if i have all these circuits can i get this single phase? ( is there a limit )

any help greatly appreciated.

 

[telectrix]

first, it's considered that the max. floor area for | RFC is 100sq.m. so that's a starting point for you.

 

[Guest123]

You do seem to have been thrown in at the deep end here.

What stage are you at in college???

Installation design is quite an involved process & a lot of it is down to the designers own best judgment with regard to number of circuits & applying diversity etc, not something that someone with little experience would handle well.

I apologise if I've mis-interpreted you, this book would be of benefit to you in this instance.

http://www.amazon.co.uk/Electrical-...5504/ref=sr_1_6?ie=UTF8&qid=1321804363&sr=8-6

 

[mick78]

thanks i will give it a look

or i just might reach for the gun!!!!!!!!!!!!!!!!!!!!!!!!!

 

[Rscott93]

sounds exactly like the type of thing that happened to me countless times during my time at darlington college.. lol

 

[goldie]

yes, make sure your ring finals are segregated, If its a country house earthing system maybe TT,
dont forget your dual split load board /rcbos and your main protective gas/water bonds.
Lecturers will always be looking for safety and also possibly cable calcs for circuits.
Make sure you dont overload with too many heavy load circuits. ie showers and cooker hob etc

 

[mick78]

cheers goldie

earthing system is indeed TT

he does want cable calcs

can i do all this in single phase?

here is what i have come up with ( dont laugh i am a novice)

d/s sockets 1 = 32A
d/s sockets 2 = 32A
d/s lights 1 = 6A
d/s lights 2 = 6A
u/s sockets 1 = 32A
u/s sockets 2 = 32A
u/s lights 1 = 6A
u/s lights 2 =6A
shower 10 kW = 50A
imm heater = 16A

is this miles out ?

can it be done single phase?

 

[telectrix]

i'd only do 1 RFC for upstairs sockets, the loading is light. separate RFC for kitchen then 1 RFC for rest of downstairs.

 

[mick78]

can i do that what about the max 100 sq m for RFC.

 

[goldie]

Yes that looks fine to me, dont forget your rcd main switch for this type of earthing arrangement.
If your using a dual rcd board dont forget to split the circuits so that if one rcd trips you still have power on each floor.
Safety ccts i.e intruder alarm and smoke detectors on rcbos. Click thanks button if its helpful mate..... Good luck!

 

[goldie]

telectrix knows his stuff mick, ive only been on for a day and he seems to be helpful in many subjects.
Kitchen ring can be an additional ring as there tend to nbe heavy loadsin there i.e kettle, iron single oven etc

 

[telectrix]

don't need RCD main switch as long as all circuits are RCD ( 30mA) protected by the 2 RCDs or RCBOs.

 

[mick78]

do i apply diversity to the mcb values or the summation of loads on circuits?

can i do this single phase?

do i have to add up all mcb values to size distribution board or load values?

think i will shoot lecturer instead.!!!!!!!!

 

[Octopus]

cheers goldie

earthing system is indeed TT

he does want cable calcs

can i do all this in single phase?

here is what i have come up with ( dont laugh i am a novice)

d/s sockets 1 = 32A
d/s sockets 2 = 32A
d/s lights 1 = 6A
d/s lights 2 = 6A
u/s sockets 1 = 32A
u/s sockets 2 = 32A
u/s lights 1 = 6A
u/s lights 2 =6A
shower 10 kW = 50A
imm heater = 16A

is this miles out ?

can it be done single phase?

Are you not including a cooker circuit(s), out buildings?

 

[Gordon]

If Earthing is TT as said on previous post then you will require a 100mA RCD mainswitch and 30mA RCBO's on the final ccts.
For ccts supplying socket outlets and lighting use the protective device rating for your diversity calculations, for ccts serving fixed equipment such as cookers
calculate the demand from the power rating and then apply diversity.