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Topic Title: RCD or not
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Created On: 04 January 2013 08:37 PM
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 04 January 2013 08:37 PM
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Nedd

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Joined: 18 February 2012

Could any one please clarify for me the following. If I was to extend an existing ring main by adding two D/G sockets, with cables less than 50mm into the wall on a circuit with ADS but no RCD. Under BS 1671 would I need to add a RCD to conform to the Regs. Thank you. 
 04 January 2013 08:40 PM
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aligarjon

Posts: 2869
Joined: 09 September 2005

Yes you would.

you could just add it to your bit that you are adding if thats possible but obviously better if to them all

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Specialised Subject. The Bleedin Obvious. John Cleese
 05 January 2013 02:55 AM
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spinlondon

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Not necessarily.
The requirement to provide RCD protection for socket-outlets only applies to those used by ordinary persons and that are intended for general use.
If the socket-outlets are not to be used by ordinary persons, or are intended for specific items of equipment, there is no requirement to provide RCD protection.

With cables concealed in walls, additional protection is required.
RCD protection combined with running the cables in prescribed zones is one method.
However, if the installation is under the supervision of a skilled or instructed person, RCD protection is not required.
 05 January 2013 09:34 AM
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aligarjon

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I'll clarify my above post so as not to confuse the OP. If he is talking about a domestic installation an rcd is required.

Gary

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Specialised Subject. The Bleedin Obvious. John Cleese
 07 January 2013 02:57 PM
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AJJewsbury

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BS 8436 cable is another option for concealed cables that wouldn't require 30mA RCD protection - which might be an economic alternative to RCDing the whole circuit especially it it involved a CU change. If the sockets were for general purpose use, RCD sockets might still be cheaper than a new CU (and provide better discrimination).

More than one way to skin a cat!

- Andy.
 07 January 2013 08:19 PM
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antric2

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The SRCD option mentioned would be most efffective way of complying or just RCBO the circuit if the con unit is capable of the upgrade.
Regards
Antric
 07 January 2013 08:36 PM
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Jaymack

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Originally posted by: antric2
The SRCD option mentioned would be most efffective way of complying

What about the new cable supplying the sockets? If less than 50mm blah blah. Perhaps an RCD protected spur could be used.

Regards
 07 January 2013 08:40 PM
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spinlondon

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Only problem with RCD FCUs, is that the manufacurers' do not consider them suitable for fixed wiring.
I know that the manufacturers' instructions only need to be taken account of.
However if the manufacturers' are stating their equipment is not suitable for a particular use, is it something that should be ignored?
 07 January 2013 08:44 PM
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antric2

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Originally posted by: Jaymack

Originally posted by: antric2

The SRCD option mentioned would be most efffective way of complying


What about the new cable supplying the sockets? If less than 50mm blah blah. Perhaps an RCD protected spur could be used.



Regards


Point taken.I am starting to lack as I approach 50
 07 January 2013 08:44 PM
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daveparry1

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That sounds a bit daft Spin, do they expect it to be connected by plug and socket then? I've fitted plenty to fixed wiring,

Dave.
 07 January 2013 08:50 PM
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DOUGIE1000

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Sorry spin, I'm with Dave on this, please explain further?

-------------------------
Dougie
Power Plus Electrical.co.uk

My mission is to live as long as possible......so far so good!
 07 January 2013 08:53 PM
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spinlondon

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The BEAMA handbook has a table indicating what use each type of RCD is intended for.
Some have ticks for fixed wiring some such as the FCU RCDs have crosses.
My understanding is that they are intended for the connection of a single item of equipment or appliance, to provide additional protection just to that item of equipment or appliance.
Here's a link:http://www.beama.org.uk/downlo...-4816-87188608E386D98D Page 26.
 07 January 2013 08:53 PM
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Jaymack

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Originally posted by: spinlondon
Only problem with RCD FCUs, is that the manufacurers' do not consider them suitable for fixed wiring.

Which manufacturers for RCD protected FSU's?

Regards
 07 January 2013 08:54 PM
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antric2

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Originally posted by: spinlondon

Only problem with RCD FCUs, is that the manufacurers' do not consider them suitable for fixed wiring.

I know that the manufacturers' instructions only need to be taken account of.

However if the manufacturers' are stating their equipment is not suitable for a particular use, is it something that should be ignored?


Blimey!!! all my connys in North Manchester are not suitable if this is correct but I doubt it.CPN instructuions dont say anything about not using in fixed wiring.
I ll not be able to use my van tyres on the road next (Sorry Spin,couldnt resist it)
Regards
Antric
 07 January 2013 08:59 PM
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Jaymack

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Originally posted by: antric2
I ll not be able to use my van tyres on the road next (Sorry Spin,couldnt resist it)

He''s been in the trenches too long, now suffering from shellshock.

Regards
 07 January 2013 09:08 PM
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spinlondon

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The second page has a list of the manufacturers that I assume the information relates to.
There's also a list of the other organisations who were involved or contributed to the guide.
Make of it what you will.
 08 January 2013 12:31 PM
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AJJewsbury

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Originally posted by: spinlondon

The BEAMA handbook has a table indicating what use each type of RCD is intended for.

Some have ticks for fixed wiring some such as the FCU RCDs have crosses.

My understanding is that they are intended for the connection of a single item of equipment or appliance, to provide additional protection just to that item of equipment or appliance.

Here's a link:http://www.beama.org.uk/downlo...-4816-87188608E386D98D Page 26.


Thanks for posting that Spin - it looks like a very interesting document!
- Andy.
 08 January 2013 01:52 PM
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lomasjs

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But it also says that FCURCD is 'Suitable as an Outgoing
Device on a CU, DB,PB or SB (5,7)Part of the Incomer'
and
Ok for Protection to Socket Outlets 20A or less

wouldn't these include fixed wiring ?

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lomasjs
 08 January 2013 02:07 PM
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spinlondon

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Originally posted by: lomasjs
But it also says that FCURCD is 'Suitable as an Outgoing
Device on a CU, DB,PB or SB (5,7)Part of the Incomer'
and
Ok for Protection to Socket Outlets 20A or less
wouldn't these include fixed wiring ?


Does seem a bit contradictory doesn't it.
I can understand how an RCCB or RCBO can be used as an outgoing device from a DB/CU, but how an FCURCD would be so used is a bit of a mystery.
If it's acceptable as a method of protection for socket-outlets, then yes, one would expect it to be acceptable for fixed wiring.
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