I've just finished tidying up the CU so there is space to fit RCBOs in place of MCBs, and it looks quite neat. But then there is a pile of blue and white spaghetti from the few RCBOs that I have already fitted.
What is the best way to treat the neutral and earth tails from the RCBOs ?
Can they be cut ?
Should they be rolled up ?
Of course its fine strand wire, so I suppose ferrules would be needed ...
Simon.

On 28/01/2019 16:06, sm_jamieson wrote:
I've just finished tidying up the CU so there is space to fit RCBOs in place of MCBs, and it looks quite neat. But then there is a pile of blue and white spaghetti from the few RCBOs that I have already fitted.
What is the best way to treat the neutral and earth tails from the RCBOs ?
Can they be cut ?
Should they be rolled up ?
Of course its fine strand wire, so I suppose ferrules would be needed ...
Simon.


I trimmed mine and used ferrules and the appropriate crimp tool (not
expensive) from RS.

--
Email does not work

On 28/01/2019 16:06, sm_jamieson wrote:
I've just finished tidying up the CU so there is space to fit RCBOs in place of MCBs, and it looks quite neat. But then there is a pile of blue and white spaghetti from the few RCBOs that I have already fitted.
What is the best way to treat the neutral and earth tails from the RCBOs ?
Can they be cut ?
Should they be rolled up ?
and then derated?





--
Robin
reply-to address is (intended to be) valid

On 28/01/2019 16:06, sm_jamieson wrote:
I've just finished tidying up the CU so there is space to fit RCBOs in place of MCBs, and it looks quite neat. But then there is a pile of blue and white spaghetti from the few RCBOs that I have already fitted.
What is the best way to treat the neutral and earth tails from the RCBOs ?
Can they be cut ?
Should they be rolled up ?
Of course its fine strand wire, so I suppose ferrules would be needed ...

They must be cut down to size (esp the neutrals)

I would not bother with ferrules for the neutrals.

The last one I did I put all the earth leads together.

Photo here of part finished job.

http://wiki.diyfaq.org.uk/images/6/6d/RCBOmeters.jpg


--
Adam

On Monday, January 28, 2019 at 6:52:14 PM UTC, ARW wrote:
On 28/01/2019 16:06, sm_jamieson wrote:
I've just finished tidying up the CU so there is space to fit RCBOs in place of MCBs, and it looks quite neat. But then there is a pile of blue and white spaghetti from the few RCBOs that I have already fitted.
What is the best way to treat the neutral and earth tails from the RCBOs ?
Can they be cut ?
Should they be rolled up ?
Of course its fine strand wire, so I suppose ferrules would be needed ...

They must be cut down to size (esp the neutrals)

I would not bother with ferrules for the neutrals.

The last one I did I put all the earth leads together.

Photo here of part finished job.

http://wiki.diyfaq.org.uk/images/6/6d/RCBOmeters.jpg


--
Adam

I was never that convinced with the need to put ferrules on all finely stranded cables to be honest. I get the point of it though. I would be inclined to twist such cable to reduce the change of it spreading away from the screw.
I tinning then end with solder considered any use in place of ferrules ?
What is the actual legal requirement/regulation for them ?

So in fact you didn't put ferrules on any of the cut tails ?
The earth ones I know are only a reference point for the RCBOs anyway - thats why they are so thin !

So if I twist together a whole lot of FE tails and put in one earth terminal that will be OK ?

Simon.

I always thought that putting lots of earth wires into a single screw terminal in a cu was bad practice.

If a screw works loose, you could potentially lose several earth connections in one go.

In the case of the functional earths, that means quite a few rcbos will then trip upon loss of functional earth.

You effectively have the behaviour of a split load cu rather than a high integrity and high availability cu.

I would personally use no more than two earth wires in one screw terminal so that you only loose one rcbo circuit plus one circuits earth should it work loose.

On Tuesday, 29 January 2019 08:47:13 UTC, sm_jamieson wrote:
On Monday, January 28, 2019 at 6:52:14 PM UTC, ARW wrote:
On 28/01/2019 16:06, sm_jamieson wrote:

I've just finished tidying up the CU so there is space to fit RCBOs in place of MCBs, and it looks quite neat. But then there is a pile of blue and white spaghetti from the few RCBOs that I have already fitted.
What is the best way to treat the neutral and earth tails from the RCBOs ?
Can they be cut ?
Should they be rolled up ?
Of course its fine strand wire, so I suppose ferrules would be needed ...

They must be cut down to size (esp the neutrals)

I would not bother with ferrules for the neutrals.

The last one I did I put all the earth leads together.

Photo here of part finished job.

http://wiki.diyfaq.org.uk/images/6/6d/RCBOmeters.jpg

I was never that convinced with the need to put ferrules on all finely stranded cables to be honest. I get the point of it though. I would be inclined to twist such cable to reduce the change of it spreading away from the screw.
I tinning then end with solder considered any use in place of ferrules ?
What is the actual legal requirement/regulation for them ?

So in fact you didn't put ferrules on any of the cut tails ?
The earth ones I know are only a reference point for the RCBOs anyway - thats why they are so thin !

So if I twist together a whole lot of FE tails and put in one earth terminal that will be OK ?

Simon.

Soldering the ends then screwing them is a big no. Solder is soft & creeps, so a tight screw becomes a completely loose screw over time.


NT

ARW wrote:

On 28/01/2019 16:06, sm_jamieson wrote:
I've just finished tidying up the CU so there is space to fit RCBOs in
place of MCBs, and it looks quite neat. But then there is a pile of blue
and white spaghetti from the few RCBOs that I have already fitted. What
is the best way to treat the neutral and earth tails from the RCBOs ?
Can they be cut ?
Should they be rolled up ?
Of course its fine strand wire, so I suppose ferrules would be needed ...

They must be cut down to size (esp the neutrals)

I would not bother with ferrules for the neutrals.

The last one I did I put all the earth leads together.

Photo here of part finished job.

http://wiki.diyfaq.org.uk/images/6/6d/RCBOmeters.jpg

Rather too much visible copper above some of the terminals for some
tastes.

--

Roger Hayter

I saw that too.....

When I wire up, I always try to have the bare wire be the same length as the terminal hole depth and the shoulder of the insulation butt up against the terminal block.

Anything that helps to protect against accidental brush contact by fingers or pointy metal tools can only be a good thing in my book.

On Tuesday, 29 January 2019 11:42:45 UTC, Roger Hayter wrote:
http://wiki.diyfaq.org.uk/images/6/6d/RCBOmeters.jpg
Rather too much visible copper above some of the terminals for some
tastes.

And a mismatched main switch so the board fails type approval?

Owain

On 29/01/2019 13:18, wrote:
On Tuesday, 29 January 2019 11:42:45 UTC, Roger Hayter wrote:
http://wiki.diyfaq.org.uk/images/6/6d/RCBOmeters.jpg
Rather too much visible copper above some of the terminals for some
tastes.

And a mismatched main switch so the board fails type approval?


Does that matter?

I thought the only extra thing with type approval was assurance that it
was good for 16kA PFC whereas individual components were only for 6 kA.

Of course if the manufacturer's instructions so you *must* not mix that
might make a difference - though in the 17th all that was required was
to "take account of manufacturers' instructions" (510.2). And I'd doubt
a court would look kindly on a manufacturer whose component failed
causing the house to burn down if they argued "it doesn't matter that
our bit was faulty, it wasn't all our kit so you can't touch us".


--
Robin
reply-to address is (intended to be) valid

On 29/01/2019 11:42, Roger Hayter wrote:
ARW wrote:

On 28/01/2019 16:06, sm_jamieson wrote:
I've just finished tidying up the CU so there is space to fit RCBOs in
place of MCBs, and it looks quite neat. But then there is a pile of blue
and white spaghetti from the few RCBOs that I have already fitted. What
is the best way to treat the neutral and earth tails from the RCBOs ?
Can they be cut ?
Should they be rolled up ?
Of course its fine strand wire, so I suppose ferrules would be needed ...

They must be cut down to size (esp the neutrals)

I would not bother with ferrules for the neutrals.

The last one I did I put all the earth leads together.

Photo here of part finished job.

http://wiki.diyfaq.org.uk/images/6/6d/RCBOmeters.jpg

Rather too much visible copper above some of the terminals for some
tastes.


I did say unfinished job:-)

That was a bit of a rushed job. I only had a couple of hours to do it
and I had a sore head that day - been out for drinks with Geoff CETLtd
the night before.

--
Adam

On 29/01/2019 11:42, Roger Hayter wrote:
ARW wrote:


http://wiki.diyfaq.org.uk/images/6/6d/RCBOmeters.jpg

Rather too much visible copper above some of the terminals for some
tastes.


Is that generally considered an issue? I like to see at least some so I
know i've got decent purchase.

So you were drunk in charge and had a lethal weapon in your right hand playing russian roulette with a fully loaded & energised CU!

😂

On Tuesday, 29 January 2019 09:59:50 UTC, wrote:
I always thought that putting lots of earth wires into a single screw terminal in a cu was bad practice.

If a screw works loose, you could potentially lose several earth connections in one go.

In the case of the functional earths, that means quite a few rcbos will then trip upon loss of functional earth.

You effectively have the behaviour of a split load cu rather than a high integrity and high availability cu.

I would personally use no more than two earth wires in one screw terminal so that you only loose one rcbo circuit plus one circuits earth should it work loose.

Actually thats a good reason for not putting both ends of a ring circuit into the same earth terminal.

And that's why I use double sockets that have two earth terminals. So one earth loops into one terminal and the other earth loops out of the other terminal.

I believe this is referred to as high integrity earthing and is recommended practice for IT equipment/server rooms/racks given that switch mode power supplies are common

On 31/01/2019 22:48, wrote:
And that's why I use double sockets that have two earth terminals. So
one earth loops into one terminal and the other earth loops out of
the other terminal.

I believe this is referred to as high integrity earthing and is
recommended practice for IT equipment/server rooms/racks given that
switch mode power supplies are common


Yes doubling the number of terminals is a good way of avoiding faults.

Its also not easy to detect the fault as a simple test will show an
earth when one side could be disconnected.

Its like rings, they are only safer if you test them a lot more
frequently than the time a fault might develop.

Its why when designing System X processors you tested the redundant
bits, its not much use having a failsafe thats broken.

Yes you are correct that if one screw terminal fails, a simple earth test at the socket will not reveal this.

The only way to test is to physically unscrew a socket, disconnect one of the earth wires and do a earth loop resistance test. Put it all back together if the test results is satisfactory.

Having said that, I still prefer sockets with two earth terminals as even if one terminal fails in socket, you still have an earth connection to all sockets until an island of unearthed sockets occurs with a second earth terminal failure.

In this case the islanded sockets lack of earth is easier to test for and hopefully these are also still protected by an rcbo with 30mA leakage threshold.....

On 31/01/2019 21:32, sm_jamieson wrote:
On Tuesday, 29 January 2019 09:59:50 UTC, wrote:
I always thought that putting lots of earth wires into a single screw terminal in a cu was bad practice.

If a screw works loose, you could potentially lose several earth connections in one go.

In the case of the functional earths, that means quite a few rcbos will then trip upon loss of functional earth.

I believe that the functional earth of a RCBO there is so that it will
still work if the neutral is lost. I do not believe that the loss of an
earth will cause the RCBO to trip.

--


Adam

On 01/02/2019 19:10, wrote:
.... snipped

Having said that, I still prefer sockets with two earth terminals as even if one terminal fails in socket, you still have an earth connection to all sockets until an island of unearthed sockets occurs with a second earth terminal failure.

.... snippedA sudden terminal failure is unlikely; what failure mode are
you concerned about?

On Monday, 28 January 2019 16:07:01 UTC, sm_jamieson wrote:
I've just finished tidying up the CU so there is space to fit RCBOs in place of MCBs, and it looks quite neat. But then there is a pile of blue and white spaghetti from the few RCBOs that I have already fitted.
What is the best way to treat the neutral and earth tails from the RCBOs ?
Can they be cut ?
Should they be rolled up ?
Of course its fine strand wire, so I suppose ferrules would be needed ...
Simon.

Well I thought, hmmm, more tools, so I ordered:
https://www.amazon.co.uk/gp/product/B07FY7GYLT

Can it really be much different to the shockingly priced:
https://uk.rs-online.com/web/p/crimp-tools/3368179/

I know "professional" tools are expensive, but ... cough.

Simon.

Simon.