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Topic Title: Changing CU's
Topic Summary: ESC advice
Created On: 26 April 2009 11:58 AM
Status: Post and Reply
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 07 May 2009 02:57 PM
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PG

Posts: 185
Joined: 17 October 2011

Originally posted by: mark2spark

Opinions please.
Went to see a CU change job, small two up two down type of house, small 4 way board main sw no rcd rewireable fuses, PME, all earths ok, 1 x ring, 1 light circuit, 1 discontinued immersion circuit (now combi boiler), 1 x cooker circuit. - - - -- - - -
The problem is that a new main switch rcd CU will fit in the cupboard space just right, a doubled up rcd board won't fit at all, an RCBO'd board (still investigating the height bit) raises a possibility of too high to fit in space. - - - - - - -
The ESC advice (at Q/A 7) states that more than one rcd should be used to minimise inconvenience when trips occur. - - - - -
So, i'd like to fit a rcd main sw 4 way board, and can't really see the problem with it.
Perhaps the red tape is obscuring my vision?


This topic was talked about in an earlier posting - similar arguments and conclusions. I am sure that you can have a single RCD incomer and the 17th Edition CUs are a con. Please see - http://www.theiet.org/Forums/f...id=205&threadid=29132

Regards
 07 May 2009 03:56 PM
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spinlondon

Posts: 4439
Joined: 10 December 2004

Originally posted by: PG
This topic was talked about in an earlier posting - similar arguments and conclusions. I am sure that you can have a single RCD incomer and the 17th Edition CUs are a con. Please see - http://www.theiet.org/Forums/f...&threadid=29132


Regards


You can have a single RCD.
The link you have posted refers to a PIR on an existing installation, and what codes and remedial action should be taken.
A single RCD would attract a code 4. As it does not comply with 341.1. If that RCD was 100mA, then it would attract a code 2 (according to the ESC), as the Regs. require 30mA for sockets that could be used for equipment outside etc.
Changing the RCD from 100mA to 30mA would cover the outside sockets, but the Cert. would have a code 4 for the existing installation, as it still wouldn't comply with 341.1.
Installing a single RCD where there was not one before, would not comply with 341.1. It would not be a defect in the existing installation, it would be a defect in the work you have carried out.
Not installing an RCD would mean that the existing installation would not comply with the Regs. However the work you have carried out would comply, as there is no requirement for the CU to contain an RCD.
The Regs. require you to address any defects and omissions in the work covered by a Cert. before issuing the Cert.
 07 May 2009 06:58 PM
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normcall

Posts: 8130
Joined: 15 January 2005

I'm so glad I'm incompetent and don't worry about others ideas about only one RCD.
As a customer said to me on Tuesday 'The regular power cuts are more inconvenient than anything you can do'. (her grill just popped the RCD!)

-------------------------
Norman
 07 May 2009 07:00 PM
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Avatar for ebee.
ebee

Posts: 5698
Joined: 02 December 2004

Originally posted by: spinlondon

Originally posted by: PG

This topic was talked about in an earlier posting - similar arguments and conclusions. I am sure that you can have a single RCD incomer and the 17th Edition CUs are a con. Please see - ">"><br "><a...id=20.....t.org.../f.....9132
...r />]http://www.theiet.org/...s/f.....9132
[/L]

]http://www.theiet.org/Forums/f...&threadid=29132
<br [/L]




You can have a single RCD.

The link you have posted refers to a PIR on an existing installation, and what codes and remedial action should be taken.

A single RCD would attract a code 4. As it does not comply with 341.1. If that RCD was 100mA, then it would attract a code 2 (according to the ESC), as the Regs. require 30mA for sockets that could be used for equipment outside etc.

Changing the RCD from 100mA to 30mA would cover the outside sockets, but the Cert. would have a code 4 for the existing installation, as it still wouldn't comply with 341.1.

Installing a single RCD where there was not one before, would not comply with 341.1. It would not be a defect in the existing installation, it would be a defect in the work you have carried out.

Not installing an RCD would mean that the existing installation would not comply with the Regs. However the work you have carried out would comply, as there is no requirement for the CU to contain an RCD.

The Regs. require you to address any defects and omissions in the work covered by a Cert. before issuing the Cert.





Regards




Mmmmmm.
I`m glad that`s all sorted then!


-------------------------
Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik

Edited: 07 May 2009 at 07:02 PM by ebee
IET » Wiring and the regulations » Changing CU's

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