Exam help (lost my notes)

[loola]

Hi

I need some help!! Can anybody explain the operations of the following components of an electrical distribution system please?

Main Consumer Unit
Residual Current Device
Catridge Fuse
Earth Wire

Thanks!!

[BigJon]

The regs book at the beginning lists the purposes for everything.
Or you could ask your lecturer

[loola]

BigJon wrote:

The regs book at the beginning lists the purposes for everything. Or you could ask your lecturer

That would be good thinking but the night before my exam and i have lost my notes it just isnt a possability!!

[davy_owen_88]

loola wrote:

Hi I need some help!! Can anybody explain the operations of the following components of an electrical distribution system please? Main Consumer Unit Residual Current Device Catridge Fuse Earth Wire Thanks!!

Main consumer unit

The first point in the 'electric chain' of any household electricity supply (thats owned and maintained by the householder). From here all other circuits are fed and protected by the fuses/MCB's/RCD's.

RCD

A device that measures the current flowing through the phase and neutral conductors and when an imbalance is detected that exceeds the rated trip value the supply is turned off.

Catridge Fuse

A cartridge which DOESN'T accept rewirable fuse wire . Connected to the consumer unit it's purpose is to break the supply in the event of an overload. The current which blows the fuse depends on the value of fuse installed.

Earth Wire

Takes many forms including:

the main equipotential bonding conductors that connect the gas and water supply pipes to the main earthing terminal
supplementary bonding conductors that link conductive metal parts in bathrooms
the main earthing conductor connecting the main earthing terminal to the earthing point.
the earth cable as part of sheathed cables.

In all cases its used as a path for fault current (except supp. where its used to limit P.d between conductive parts to reduce the risk of shock) Earthing is needed to allow a large enough current to flow from phase to earth so that the protective devices can activate so as to remove the danger.

You might want to read the regs for the actual 'text-book' answers as what I've written will not contain all the info you need to answer your questions.

Davy

EDIT:

loola wrote:

That would be good thinking but the night before my exam and i have lost my notes it just isnt a possability!!

Well my above answers are written for joe-public to provide a basic understanding, its probably not suitable for an exam answer. I'm sure someone will come along and add bits of info or even be kind enough to write out the explanations given in the regs.

[loola]

davy_owen_88 wrote:

loola wrote: Hi I need some help!! Can anybody explain the operations of the following components of an electrical distribution system please? Main Consumer Unit Residual Current Device Catridge Fuse Earth Wire Thanks!! Main consumer unit The first point in the 'electric chain' of any household electricity supply. From here all other circuits are fed and protected by the fuses/MCB's/RCD's. RCD A device that measures the current flowing through the phase and neutral conductors and when an imbalance is detected that exceeds the rated trip value the supply is turned off. Catridge Fuse A cartridge which accepts rewirable fuse wire. Connected to the consumer unit it's purpose is to break the supply in the event of an overload. This overload depends on the value of fuse wire installed in the cartridge fuse. Earth Wire Takes many forms including: the main equipotential bonding conductors that connect the gas and water supply pipes to the main earthing terminal supplementary bonding conductors that link conductive metal parts in bathrooms the main earthing conductor connecting the main earthing terminal to the earthing point. the earth cable as part of sheathed cables. In all cases its used as a path for fault current (except supp. where its used to limit P.d between conductive parts to reduce the risk of shock) Earthing is needed to allow a large enough current to flow from phase to earth so that the protective devices can activate so as to remove the danger. You might want to read the regs for the actual 'text-book' answers as what I've written will not contain all the info you need to answer your questions. Davy

Brilliant Thanks very much!!

Since it sounds like you know what you are talking about any idea about this one....

explain 3 functions of an electrical conduit system?

Thanks

[CookyMan9999]

LOL davvy why don't you just go and sit the exam har har

[ricicle]

[quote="davy_owen_88]Catridge Fuse

A cartridge which accepts rewirable fuse wire. Connected to the consumer unit it's purpose is to break the supply in the event of an overload. This overload depends on the value of fuse wire installed in the cartridge fuse.

.[/quote]

Wrong - A semi-enclosed fuse accepts fuse wire, a cartridge fuse is one that cannot be re-wired and is usually of a high breaking capacity

[davy_owen_88]

CookyMan9999 wrote:

LOL davey why don't you just go and sit the exam har har

Why does everyone write 'Davey' I even write my name at the bottom of every post and its next to every post I make

And the reason I don't sit the exam is because as ricicle has pointed out, I have a tendency to confuse certain terms and make myself look like a retard, lol.

[loola]

so does anybody fancy helping me out and even letting me know what a conduit system is?

Please?!!

[ricicle]

A conduit system is made up of various sizes of tube (steel/pvc) that have manufactured fittings available for direction changes, terminations etc.The tubes can be cut to length and bent as well to follow building contours.
Single, insulated cables are normally drawn into the tubes making wiring fairly easy once the tubes have been installed.
The conduit offers better mechanical protection, especially steel, than clipped cables and can be rewired fairly straightforwardly when or if needed
Special tools are required to install conduit, particularly steel, but when finished can look very neat

[loola]

ricicle wrote:

Is that a yes?

Thanks for your help on the cartridge fuse!!

[BigJon]

A conduit system is used to run/protect single core cables
Its basically metal tubing and mainly comes in black enamel or galvanised.

*beaten by better explanation above*

[ricicle]

see my edited post above, the was for davy

[loola]

so am i right in saying that three functions of an electrical conduit system would be


1, the cables can bend to follow the contours of a building

2, the conduit offers better mechanical protection than clipped cables

3, it can be rewired fairly easily if needed.


Thanks everyone for all your help!!

I know it looks bad the night before the exam and i seem to have very little knowledge on the topic but it is just one out of 5 topics from my services exam for a construction management degree, so everyone thanks so much!!!

[ricicle]

Not sure about No.1