Planning Kitchen Wall Electrics - Is This Good? [PIC]

[deadshort]

That is often the case, if one can't understand what is being said without pictures. However, in this case, I would have thought that any even remotely intelligent person could understand what is meant by a ring with loads at "3, 6 and 9 o'clock" relative to a CU.

Kind Regards, John

Where is the CU ?

 

[JohnW2]

Yes you're spot on, and the original cable is indeed no longer carrying any ring current, but it would still be carrying current relating to any accessories on that part of the ring, if I had included any in my example.

Fair enough. That might be relevant in terms of whatever was being discussed in the initial part of this thread (which I haven't yet read) but I was commenting (at your request!) on what appeared to be a general statement about cross-bridges in rings in general.

If, as in what (all) you described, there are no loads connected to the cable that has been 'bypassed' by a connection of negligible impedance, then this really is not a 'bridging' but merely a shortening of (one side of) the ring.

Kind Regards, John

 

[deadshort]

in the initial part of this thread (which I haven't yet read)

 

[JohnW2]

Where is the CU ?

As was stated, ....

... ring final, CU at 12 o clock ...

Kind Regards, John

 

[JohnW2]

Things clearly haven't changed around here. I think I'll probably go back into hibernation.

Kind Regards, John

 

[deadshort]

Me thinks big ego …….

 

[John D v2.0]

Things clearly haven't changed around here. I think I'll probably go back into hibernation.

Kind Regards, John

You should try the plumbing area
I visited a forum about building garden workshops and kitting them out etc, and I was amazed how constructive everyone was. Basically everyone was like you are.
I was thinking why can't here be more like that, even between the building, electric and plumbing sections here there are completely different cultures!

 

[deadshort]

You should try the plumbing

 

[John D v2.0]

Fair enough. That might be relevant in terms of whatever was being discussed in the initial part of this thread (which I haven't yet read) but I was commenting (at your request!) on what appeared to be a general statement about cross-bridges in rings in general.

If, as in what (all) you described, there are no loads connected to the cable that has been 'bypassed' by a connection of negligible impedance, then this really is not a 'bridging' but merely a shortening of (one side of) the ring.

Kind Regards, John

Yep indeed,
So why this is relevant is in the mists of page 3

, any time both legs of the ring are in the same place, then a ring is, itself, pointless.
If what you say is wanted, use 4mm² for the spur from the position where it stops actually being a ring.

so the debate was whether it's pointless to spread the loads on the ring or just connect them as a point load using 4mm cable.
I don't think I fully understand the reason why it does or doesn't make a difference as I haven't got a clear idea of the point we're trying to decide.
But in the mean time I've learnt some other stuff!

 

[JohnW2]

Yep indeed, .... So why this is relevant is in the mists of page 3 .... so the debate was whether it's pointless to spread the loads on the ring or just connect them as a point load using 4mm cable.
I don't think I fully understand the reason why it does or doesn't make a difference as I haven't got a clear idea of the point we're trying to decide.

Nor have I and, as I said (even if it prompted predictable attempts at ridicule), when I have the time I need to read the whole of this thread to ascertain exactly what was being discussed.

Assuming Method C, having a number of loads connected via a 4mm unfused spur from a 32A ring is not materially different from having all the loads fed from very-close-to-one-another sockets/FCUs which are part of the ring. Whether either of those situations is satisfactory (in terms of the ring) depends upon the magnitude of the loads and how close to one end of the ring they originate.

Kind Regards, John

 

[EFLImpudence]

Hello John.

the ring happens to be physically like a lollipop shape, so the cables between logical 3 o clock and 6 o clock positions are physically run together.
I bridge between the 3 o clock and 6 o clock positions

consider the current in each leg now?
a) 20a will go 2/3 anticlockwise (13.3a), 1/3 clockwise (6.6a)
b) 6a will go 2/3 anticlockwise (4a) , 1/3 clockwise (2a) (as it's connected to a by negligible impedance)
c) will go 1/3 anticlockwise (2a), 2/3 clockwise (4a)
anticlockwise total at the CU: 19.3a
clockwise total at the CU: 12.6a

An easier way to describe the alteration would be to say.

Connect together the 3o'clock and 6o'clock points.

 

[ban-all-sheds]

I would have thought that any even remotely intelligent person could understand what is meant by a ring with loads at "3, 6 and 9 o'clock" relative to a CU.

There was more going on than just that.

 

[JohnW2]

I visited a forum about building garden workshops and kitting them out etc, and I was amazed how constructive everyone was. Basically everyone was like you are. I was thinking why can't here be more like that ...

It's obviously not the forums/whatever, per se, but, rather, the people who participate in them. Although, as you observe, there are some refreshing exceptions, most of these places have some (usually very small numbers of) 'regulars' who make participation less pleasant than it can/should be for everyone else.

Many probably just laugh all the less-than-welcome bits as 'banter' but it is when (as I have just done) one dips ones toes back in the water after an appreciable period of absence that one really does wonder whether the atmosphere is really one that one needs or wants to 'voluntarily' subject oneself to. That's certainly what I am currently thinking/wondering.

Kind Regards, John

 

[JohnW2]

Hello John.

Hi. I trust all is well.

An easier way to describe the alteration would be to say. Connect together the 3o'clock and 6o'clock points.

Indeed, provided one made it clear that the 'connection' was one of negligible impedance.

Perhaps even better/simpler (provided nothing else was connected to the cable originally between those two points) would be to simply say that the alteration was to change the 3 o'clock and 6 o'clock points to one single point (described as being at whatever point on the clock-face you want!) and throw away the cable which originally joined them. I do not regard that as 'bridging a ring'.

Kind Regards, John

 

[John D v2.0]

Nor have I and, as I said (even if it prompted predictable attempts at ridicule), when I have the time I need to read the whole of this thread to ascertain exactly what was being discussed.

Assuming Method C, having a number of loads connected via a 4mm unfused spur from a 32A ring is not materially different from having all the loads fed from very-close-to-one-another sockets/FCUs which are part of the ring. Whether either of those situations is satisfactory (in terms of the ring) depends upon the magnitude of the loads and how close to one end of the ring they originate.

Kind Regards, John

Exactly - using the 4mm cable rather then separate legs forces all the accessories on the 4mm cable to be artificially very-close-to-one-another on the ring even when they wouldn't be in the 2x2.5 situation.
I think you've already clarified my original thought and summarised what I meant perfectly

Although in the op case they were actually electrically close anyway.