Level 2 student

[Taylortwocities]

I was kinda hoping that @Rash55 was going to figure it for himself.

 

[morqthana]

I was kinda hoping that @Rash55 was going to figure it for himself.

Why should he bother when other people are doing it for him?

Anyway - his tutor is going to think he's a star pupil.

 

[securespark]

I think for the top question, the wording could have been more succinct.
I'm sure it made sense to the writer.

I think the radial and the ring final are two separate circuits. A radial for the top accessory and a ring final for the three sockets below.

Because, if you think about it, however you attach that top accessory to the three sockets, it isn't a radial. In one layout, it's a spur off the ring final and in the other it's part of the ring final.

So I think the correct answer is to draw the top accessory having a single feed from one CPD in the board and the sockets being fed from another in a ring final formation.

I can't read the number on the second from the right CPD in the board, is it 20?

And the first is 32?

If I'm correct, make sure to get those the right way round.

 

[ebee]

I agree with secure, slightly,

the wording could have been more succinct.

Certainly could.
It`s asked for a ring and itsasked for a radial and its asked for 3 sockets.
That does not specifically exclude the 4 terminal device (FCU or DP Sw) so with or without and whether you include or exclude or whatever you figure them to achieve will be correct.

 

[morqthana]

It`s asked for a ring and itsasked for a radial and its asked for 3 sockets.

And nowhere does it ask for that DP switch or FCU, or whatever, to be connected in any way.

That does not specifically exclude the 4 terminal device (FCU or DP Sw) so with or without and whether you include or exclude or whatever you figure them to achieve will be correct.

One of the things people need to learn is the importance of installing according to the instructions they are given, not according to what they think the person giving the instructions "actually meant" and deciding that they should "interpret" what was actually written in a different way.

"3 Sockets", not "3 sockets and 1 FCU".

Connecting the FCU would not be correct.

 

[securespark]

Is it an FCU?

Going back to the wording of the top question, clearly it is ambiguous.

The forward slash suggests it's a choice of one or the other: a radial or a ring and why haven't they used the word final after the word ring?

We know that isn't what the question setter intended, because the second question covers the same scenario in a ring final format.

It's very sloppy.

 

[morqthana]

Fellow class mate sent me this how the radial should be done.

How did he decide what the csa and installation method of the cable was?

 

[securespark]

That's not part of this task.

 

[endecotp]

Recently started level 2 part time evenings.

Out of curiosity, could someone who knows please explain how long someone who has “recently started level 2” has already been studying, and how many years they have to go?

 

[BS3036]

...and what have they learned in the last year...?

 

[morqthana]

Is it an FCU?

Probably, but wrt connecting it to a supply, that doesn't matter.

Going back to the wording of the top question, clearly it is ambiguous.

No, it isn't.

Read what is written.

What is at the top is not a question, it is a heading.

"Task 8. PVC PVC Cable: Radial/Ring Circuit 3 sockets"

The actual task to accomplish is halfway down the page

"Task: 8: Complete a Wiring Diagram for a Ring circuit in Colour."

The forward slash suggests it's a choice of one or the other: a radial or a ring

Or that this part of the workbook covers both radials and rings. Possibly with and without branches and spurs.

Do we know that p14 does not ask for a diagram for a radial? No, we don't.

Do we know that pp14 onwards don't ask for the (probable) FCU to be added as a spur, or a branch, or as part of the circuit? No, we don't.

and why haven't they used the word final after the word ring?

And why do people insist that it should always be used? Fair enough to object to the term "ring main", but final circuits an have a radial topology or a ring topology.

If "radial" instead of "radial final" is OK, then why not "ring" instead of "ring final"? What's the difference?

We know that isn't what the question setter intended, because the second question covers the same scenario in a ring final format.

See above - there is only one question. There may be another one, or other ones, on subsequent pages.

It's very sloppy.

On the face of it it could certainly have been done better, but without sight of the subsequent page(s) we don't know how sloppy it is.

If the workbook had looked like this:

I wonder what sort of discussion we'd be having....

 

[morqthana]

That's not part of this task.

We don't know that.

The radial circuit might be the second question in Task 8.

 

[morqthana]

...and what have they learned in the last year...?

That might depend on how much they did for themselves and how much they cribbed from others...

 

[ericmark]

Do you remember

Competent person. A person who possesses sufficient technical knowledge, relevant practical skills and experience for the nature of the electrical work undertaken and is able at all times to prevent danger and, where appropriate, injury to him/herself and others.
Skilled person. A person with technical knowledge or sufficient experience to enable him/her to avoid dangers which electricity may create.

It came up in nearly every exam, and you had to understand the difference between the two. Latter editions don't have the two definitions but it was rather silly, the "and others" one would hope a skilled person also made safe.

So we have to work out how pedantic the marking will be, OK I saw it as a bit of fun, when

Tell him sockets need to be rcd protected

Lower you didn't out the fly lead to the neutral bar

But we don't know, maybe they did want to see RCD protection? The diagram in the text book, to wire up a florescent lamp when I did my 'A' level physics in around 2010 had completely missed out the ballast.

So it does not ask for a ring final, a ring is designed so any part of the ring can be isolated to be worked on without losing the supply, the ring final is to save copper after world war II during the housing rebuild to replace those homes which had been bombed.

As to if any reason for the ring final any more, it is up for debate, as building regulations which ask for penetrations on beams to be 1/3 lengths from the ends, the length of cable can easy exceed the 106 meter limit widely considered as volt drop limit.

Basic consideration is how big is the area which the ring final or radial needs to cover, "(iv) taking account of the total floor area being served. (Historically, limit of 100 m² has been adopted.)".

So if we consider a house with 4 rooms up and down, each 8 foot high, and the sockets are all on the internal walls, to get from one socket to the next one being on lower room and next on upper room, we have 8 foot (2.4 meters) - 350 mm on lower and 8 foot plus 350 mm on upper and 5/3 meters socket to the cross over point in the beams, so 8 meters on top of the distance travelled along the wall, so wall is 10 meters long, so that's 20 meters of cable, so 110 meters on one wall so 90 / 8 = 22 socket maximum or around 5 sockets per room, and that is when all on the internal wall. So the 1/3 rules has resulted in the ring final easily exceeding the 110 meter total.

But a 20 amp radial is allowed 32 meters of cable for same volt drop of 11.5 volts. So one needs 3 radials to replace one ring. So a lot down to how the beams run in the house, as to which method can be used.

However, it is reasonably clear, for 3 sockets and a FCU one would not use a ring final.

But it does seem common sense is not used, simple thing, a caravan on a 16 amp RCBO at the site supply, why would any consumer unit in the caravan ever have a 16 amp MCB or RCBO? even with just 1 amp going to lights, the site MCB/RCBO should always trip first, same goes for a supply to a garage, 16 amp in the house, then garage consumer units with 20 amp overloads in it. And often sockets arranged in a ring final configuration. Why?

The old wiring regulations use to say, common sense should prevail, today that seems have been thrown out with the bath water.

 

[morqthana]

So we have to work out how pedantic the marking will be, OK I saw it as a bit of fun, when

Tell him sockets need to be rcd protected

But we don't know, maybe they did want to see RCD protection?

The device on the right might be an RCD.

So it does not ask for a ring final, a ring is designed so any part of the ring can be isolated to be worked on without losing the supply,

In the context of the circuit possibilities for a few sockets fed from a 4-way CU, there are:

1. A radial final
2. A ring final
3. A ring designed so any part of it can be isolated to be worked on without losing the supply

Really?

the ring final is to save copper after world war II during the housing rebuild to replace those homes which had been bombed.

More like a way to increase the capacity of existing 15A radials with a quick and easy mod?