wiring sizes inside CU
 

Usually 25mm meter tails go into the CU these days (up to 100A)
The norminal sizes of internal connections for a standard split CU, neutral and live connections, etc. seems to be 16mm. For a split CU, you could say only part load is on each neutral connection I suppose.
But then the neutral connections narrow down on a reducing pin crimp to perhaps 10mm or less.
Then the neutral bars may be connected by a similar small dimension link.
For example look at the U-shaped bare copper neutral link (factory fitted) in the photo linked to below.

If the meter tails are 25mm surely the neutral connection from the switch to the neutral bar should be the same, but it is only 16mm. And also the neutral bar itself does not seem all that chunky.

The exception is perhaps the live bus bar, which is a couple of millimetres thick, but are quite large surface area.
But the same current is going through the bus bar as the neutral to main switch link.

Is this simply a case of relatively short connections are OK in a reduced dimension ?

Here is a picture of part of my CU (in photobucket):

https://i1139.photobucket.com/albums...tral%20bar.jpg

Just wondering,
Simon.

wiring sizes inside CU
 

On 19/01/2019 15:48, sm_jamieson wrote:
Usually 25mm meter tails go into the CU these days (up to 100A)
The norminal sizes of internal connections for a standard split CU, neutral and live connections, etc. seems to be 16mm. For a split CU, you could say only part load is on each neutral connection I suppose.
But then the neutral connections narrow down on a reducing pin crimp to perhaps 10mm or less.
Then the neutral bars may be connected by a similar small dimension link.
For example look at the U-shaped bare copper neutral link (factory fitted) in the photo linked to below.

If the meter tails are 25mm surely the neutral connection from the switch to the neutral bar should be the same, but it is only 16mm. And also the neutral bar itself does not seem all that chunky.

The exception is perhaps the live bus bar, which is a couple of millimetres thick, but are quite large surface area.
But the same current is going through the bus bar as the neutral to main switch link.

Is this simply a case of relatively short connections are OK in a reduced dimension ?

Here is a picture of part of my CU (in photobucket):

https://i1139.photobucket.com/albums...tral%20bar.jpg

Just wondering,
Simon.


It is the resistance that is important and on the short link that is
minimal.

wiring sizes inside CU
 

I do often wonder however, if a load is switched and there is a short length
of reduced conductivity, would the output on anything connected from that
point also be more prone to some kind of interference, Ie a high start load
momentarily putting a notch into the voltage, or is the crud generally on
mains supplies now so bad that nobody should notice. I notice for example
that I can hear the thud when a 3KW fan heater cuts in on the same ring as
my stereo is on. Not loud, but you can hear it.
Brian

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On 19/01/2019 15:48, sm_jamieson wrote:
Usually 25mm meter tails go into the CU these days (up to 100A)
The norminal sizes of internal connections for a standard split CU,
neutral and live connections, etc. seems to be 16mm. For a split CU, you
could say only part load is on each neutral connection I suppose.
But then the neutral connections narrow down on a reducing pin crimp to
perhaps 10mm or less.
Then the neutral bars may be connected by a similar small dimension link.
For example look at the U-shaped bare copper neutral link (factory
fitted) in the photo linked to below.

If the meter tails are 25mm surely the neutral connection from the switch
to the neutral bar should be the same, but it is only 16mm. And also the
neutral bar itself does not seem all that chunky.

The exception is perhaps the live bus bar, which is a couple of
millimetres thick, but are quite large surface area.
But the same current is going through the bus bar as the neutral to main
switch link.

Is this simply a case of relatively short connections are OK in a reduced
dimension ?

Here is a picture of part of my CU (in photobucket):

https://i1139.photobucket.com/albums...tral%20bar.jpg

Just wondering,
Simon.


It is the resistance that is important and on the short link that is
minimal.

wiring sizes inside CU
 

On 20/01/2019 09:38, Brian Gaff wrote:
I do often wonder however, if a load is switched and there is a short length
of reduced conductivity, would the output on anything connected from that
point also be more prone to some kind of interference, Ie a high start load
momentarily putting a notch into the voltage, or is the crud generally on
mains supplies now so bad that nobody should notice. I notice for example
that I can hear the thud when a 3KW fan heater cuts in on the same ring as
my stereo is on. Not loud, but you can hear it.
Brian

That is highly unlikely to be mains bourne and more like RFI transients
at the switch and direct detection of same in the front end of your stereo.

wiring sizes inside CU
 

On Saturday, 19 January 2019 15:48:54 UTC, sm_jamieson wrote:

Usually 25mm meter tails go into the CU these days (up to 100A)
The norminal sizes of internal connections for a standard split CU, neutral and live connections, etc. seems to be 16mm. For a split CU, you could say only part load is on each neutral connection I suppose.
But then the neutral connections narrow down on a reducing pin crimp to perhaps 10mm or less.
Then the neutral bars may be connected by a similar small dimension link.
For example look at the U-shaped bare copper neutral link (factory fitted) in the photo linked to below.

If the meter tails are 25mm surely the neutral connection from the switch to the neutral bar should be the same, but it is only 16mm. And also the neutral bar itself does not seem all that chunky.

The exception is perhaps the live bus bar, which is a couple of millimetres thick, but are quite large surface area.
But the same current is going through the bus bar as the neutral to main switch link.

Is this simply a case of relatively short connections are OK in a reduced dimension ?

Here is a picture of part of my CU (in photobucket):

https://i1139.photobucket.com/albums...tral%20bar.jpg

Just wondering,
Simon.

What xsa are those conductors?
The biggest loads only flow through part of the bar, not all.


NT

wiring sizes inside CU
 

On Sun, 20 Jan 2019 08:39:43 -0800, tabbypurr wrote:

What xsa are those conductors?
The biggest loads only flow through part of the bar, not all.

If you're talking about the skin effect, it's really not a factor at 50Hz.




--
Leave first - THEN negotiate!

wiring sizes inside CU
 

On Sunday, 20 January 2019 16:58:13 UTC, Cursitor Doom wrote:
On Sun, 20 Jan 2019 08:39:43 -0800, tabbypurr wrote:

What xsa are those conductors?
The biggest loads only flow through part of the bar, not all.

If you're talking about the skin effect, it's really not a factor at 50Hz.

I didn't mention the skin effect.


NT

wiring sizes inside CU
 

On Sun, 20 Jan 2019 09:30:50 -0800, tabbypurr wrote:

On Sunday, 20 January 2019 16:58:13 UTC, Cursitor Doom wrote:
On Sun, 20 Jan 2019 08:39:43 -0800, tabbypurr wrote:

What xsa are those conductors?
The biggest loads only flow through part of the bar, not all.

If you're talking about the skin effect, it's really not a factor at
50Hz.

I didn't mention the skin effect.


NT

So what, then? Current crowding? What's the phenomenon you're referring
to?



--
Leave first - THEN negotiate!

wiring sizes inside CU
 

Cursitor Doom wrote:

On Sun, 20 Jan 2019 09:30:50 -0800, tabbypurr wrote:

On Sunday, 20 January 2019 16:58:13 UTC, Cursitor Doom wrote:
On Sun, 20 Jan 2019 08:39:43 -0800, tabbypurr wrote:

What xsa are those conductors?
The biggest loads only flow through part of the bar, not all.

If you're talking about the skin effect, it's really not a factor at
50Hz.

I didn't mention the skin effect.


NT

So what, then? Current crowding? What's the phenomenon you're referring
to?

He probably means part of the bar longitudinally rather than
transversely.

--

Roger Hayter