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#137060 - 05/24/03 08:28 AM Who needs Circuit breakers anyway?  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
I've been moving some images around on ECN's server, and found some from older threads that I thought are worth posting again for the benefit of newer ECN members who might have missed them first time round.

This distribution panel is one that I haven't forgotten in a hurry. With all the branch breakers turned off, there was still power throughout the house. Not surprising when I saw how the panel had been wired:

[Linked Image]
[Linked Image]
[Linked Image]

The only OCPD for every circuit, including the tiny 1 sq. mm lighting branches was the main PoCo fuse.


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#137061 - 05/24/03 09:31 PM Re: Who needs Circuit breakers anyway?  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
So, did tha ace installer figure the top terminals were "spares"?


#137062 - 05/24/03 10:29 PM Re: Who needs Circuit breakers anyway?  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,211
SI,New Zealand
Paul,
I remember this one!.
That busbar at the bottom of the breakers looks a little dangerous, I don't think I'd like to work on this unit live.
What sort of current rating does it have?.(the busbar)
Also, are them meter tails double insulated?, you'd think that there would be some cable sheathing over them as they come into the unit, although its only plastic that its going through.
That's a good idea having colour coded toggles on the breakers!.
One thing I hate about units like this is, although they are nice and compact, they often don't have adequate space for wiring and to get your fingers into, should the need arise!. [Linked Image]

[This message has been edited by Trumpy (edited 05-24-2003).]


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#137063 - 05/26/03 03:13 PM Re: Who needs Circuit breakers anyway?  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
The unit is the typical domestic panel rated for 100A maximum. The main on the right is purely a double-pole switch, not a circuit breaker (this model will take a main RCD in place of the switch, if required, but in this house there was an older ELCB mounted separately).

These Wylex panels do actually have a plastic protective cover which fits into those black plastic clips and covers the live busbar assembly. I can't remember whether I'd already removed it before taking these photos or whether the cover was missing.

The tails were double-insulated, as I recall. These days, the norm is for both cables to have an outer gray sheath over the red and black, but at one time these were made with the outer sheath matching the color of the inner insulation. (The other combination, still found sometimes in older installations, had a brown outer sheath on both.)

The lack of working space is one of my main criticisms of many British electrical accessories.


[This message has been edited by pauluk (edited 05-26-2003).]


#137064 - 05/26/03 06:21 PM Re: Who needs Circuit breakers anyway?  
Bjarney  Offline
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Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
Aside: Paul, by UK standards where on the premises is neutral and earth joined? [That is, if they are joined.]


#137065 - 05/27/03 08:28 AM Re: Who needs Circuit breakers anyway?  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
This particular house, like many in this area, uses the "TT" earthing system, so there is no neutral-ground bond on the premises. The old TN-S systems also have no N-G bond at the house.

In a TN-C-S (PME) installation, neutral and earth are bonded together on the premises, but not at the main panel. The bonding point is at the cut-out ahead of the meter.

Here is the schematic outline of the systems.


#137066 - 05/27/03 07:45 PM Re: Who needs Circuit breakers anyway?  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
Paul, I'd completely forgotten about the E-C.net Reference drawings. Thanks for the pointer.


#137067 - 05/30/03 06:53 AM Re: Who needs Circuit breakers anyway?  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
No problem. It's been a while since the different grounding methods used on this side of the Big Pond have been discussed, so it might be worth re-posting a brief outline of our different systems with links to the diagrams. [Linked Image]


#137068 - 05/30/03 02:40 PM Re: Who needs Circuit breakers anyway?  
Bjarney  Offline
Moderator
Joined: Apr 2002
Posts: 2,527
West-Southern Inner-Northeast ...
https://www.electrical-contractor.net/ubb/Forum15/HTML/000064.html is the link to Scott35’s Techical Reference Section.

His new job seems to have him swamped and making money hand over fist and them some, I’ll bet. That and spending it all on wild weekends in Barstow.   ;-)

https://www.electrical-contractor.net/ubb/Forum15/HTML/000074.html [Topic: UK systems Drawings] illustrates the UK’s TN-S, TN-C-S and TT system-grounding practices.




[This message has been edited by Bjarney (edited 05-30-2003).]



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