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Topic Title: 13amp fused RCD
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Created On: 10 April 2017 03:48 PM
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 10 April 2017 03:48 PM
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jcm256

Posts: 2285
Joined: 01 April 2006

Whet's the forum view in fitting a 13amp 30mA RCD in a bathroom for a power shower, foolish it may be considering the number of seized cord pull switched I changed, well the majority were due overheating terminals melting the plastic inners, only some were due to water condensate ingress.
This bathroom is built as lean to against double brick and cavity wall and I ant boring a hole through just to put a 1.5mm in through and out again to mount a RCD.
This is the sort of device do not know IP rating.

https://www.amazon.co.uk/Selectric-SP-RCD13FCU-Protected-Fused-Connection/dp/B00GJ3HI6Q/ref=pd_bxgy_60_img_2?_encoding=UTF8&psc=1&refRID=3YWPS2QMREV647VRJGE0
 10 April 2017 04:15 PM
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pww235

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Why not stick the RCD at the board location (either RCBO or separate RCD in an adjacent enclosure)?
 10 April 2017 05:26 PM
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jcm256

Posts: 2285
Joined: 01 April 2006

Thanks, your suggestion would be too awkward in this case, the shower only takes 3amps and will be fused as such, and intend to take the supply from a fan spur unit already in the bathroom. The last one I did of this type I put the spur unit and RCD in the roof space, but that one was low voltage and the transformer was already located in the roof space. This one is mains supply. Thanks for your reply will carry on with my project when get time.
 10 April 2017 05:41 PM
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geoffsd

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Then why not put the RCD at the origin of the fan circuit?
 10 April 2017 06:59 PM
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jcm256

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Yes a good suggestion, the consumer unit is old re-wire able RCBO don't fit and no room even to the side or below, I see you are steering me away from fitting RCD in bathroom and will act accordingly.
Thanks.
jcm
 10 April 2017 08:59 PM
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Dave69

Posts: 600
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So if you are touching the wiring for the fan in the bathroom it should be rcd protected along with the lighting circuit so basically you need to fit a rcd to protect that circuit, if there is no room in or by the board then walk away or change the board, unless its a cash job with no certs
 10 April 2017 09:15 PM
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daveparry1

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Where is the pump positioned? Most of them are outside the bathroom, if this is the case rcd might not be necessary.
 10 April 2017 10:52 PM
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jcm256

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The pump is inside the shower, the actual one is shown below. Low pressure system needs hot and cold. The existing gravity feed mixing valve type shower flow was not powerful enough therefore altering pipes straight to the power shower. I always liked working with chrome pipes and bends Thank you for your time.

https://www.amazon.co.uk/Triton-AS2000XT-Thermostatic-Integral-Shower/dp/B004VF5NMU



Regards
jcm

Edited: 11 April 2017 at 09:04 AM by jcm256
 14 April 2017 05:53 PM
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mapj1

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If you don;t like plugs and sockets, and I agree its a bit rough, any chance of an RCD fused spur
like thiws, perhaps above the bathroom door on the outside ? Thinking maybe mini trunking dropping from the ceiling..

-------------------------
regards Mike
 14 April 2017 07:20 PM
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spinlondon

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My understanding, is that the circuit has to have RCD protection, not just the part of the circuit which enters the location.
 14 April 2017 11:50 PM
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mapj1

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Depends on the cable type and route that feeds it, and if it is a new circuit surely ?

Pre-existing circuit, or cables deeper than 50mm, or surface wired or earthed armour, or conduit etc .. then maybe we do not need RCD for that section ?

Edited to clarify what I was thinking, and your view may be different...
I'd suggest it depends where the 'new circuit' starts perhaps and how crummy the rest looks. Equally I don't normally consider a simple fused spur to be the origin of a new circuit, just a step down in disconnection time and a step up in max permitted Zs of the circuit it spurs from.
In the same way I don't consider a centre fed radial to be 2 circuits that share a breaker, just one with more than one far point, and more than one Zs test to do. However, I fully understand that others may do things differently, and perhaps I am not being very logical.

New or not there is no doubt however that it is better to have the bit in the bathroom on RCD at least.
The regs certainly require that, though one may ask if the RCD has to be inside the consumer unit, or just in the line in a sensible place between it and the load.

Additional protection by RCDs
Additional protection shall be provided for all circuits of the location, by the use of one or more RCDs having the characteristics specified in Regulation 415.1.1.


If you were starting from scratch, then you'd be best to have an RCD or RCBO at the board, but my understanding is that is not so simple in the case here.

-------------------------
regards Mike


Edited: 16 April 2017 at 05:24 PM by mapj1
 15 April 2017 05:56 AM
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spinlondon

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If the requirement is to provide RCD protection for the circuit, how would protecting only part of the circuit comply?
 15 April 2017 03:07 PM
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AJJewsbury

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If you're installing a RCD FCU outside the bathroom circuit then the whole circuit supplying that bathroom is RCD protected (if you believe BS 7671's definition of a circuit). (Or of course you could substitue the RCD FCU with a mini CU with RCCB just outside the bathroom with the same effect if that's what your religion demands)
- Andy.
 15 April 2017 05:50 PM
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spinlondon

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Well there's a couple of problems there Andy.
One I'm not religious.
Two can anyone confirm that an RCD FCU is suitable for protecting fixed wiring (Beama says not)?
Three, being quite happy with the definition in BS7671, I expect you to always notify and issue an EIC whenever you plug something into a socket.
Four if you feel the same level of safety is provided as would be by compliance with the Regulations, then why not just list it as a departure?
Five why faff around trying to get round the Regulations when compliance is not hard?

Remember, it's not rocket science.

Edited: 16 April 2017 at 04:29 PM by spinlondon
 16 April 2017 01:46 PM
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jcm256

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That 13amp RCD fused spur unit that mapj1 put on is just the job for this situation even the RCD switch would be tested every time you switched on and off the shower supply.

From the leaflet that comes with this shower it says in most cases 1mm twin and earth will be adequate, well ok for only 3amps load but in this country we have allowed reduced diameter earth in our twin and earth In, Ireland electrical regulations that's not allowed. Spain you have the large earth single cable poking out of every light point and socket at first fix. The 1.5 mm I used the earth is akin to the diameter of a fuse wire and this is the only means of earthing the shower, so extra care needed at connections. As you know the copper or chrome pipe work to all showers is now a push on connection to the plastic inlet fitting or fittings, so no additional earth protection from there. BS7671 can't cater for every technical proposition but as regards showers should have a regulation regarding min earthing conductor size.

Thanks for your information,
Regards
jcm
 16 April 2017 02:08 PM
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geoffsd

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Originally posted by: jcm256That 13amp RCD fused spur unit that mapj1 put on is just the job for this situation even the RCD switch would be tested every time you switched on and off the shower supply.

As with a normal switch, there would be no reason to use it every time the shower is used.

As you know the copper or chrome pipe work to all showers is now a push on connection to the plastic inlet fitting or fittings, so no additional earth protection from there.

Earthing is not a good thing in its own right.
It is a way of disconnecting the supply in the event of a fault.
It would be better if there were another means of protection and nothing required earthing.

Anyway, the shower will have no exposed-conductive-parts.

BS7671 can't cater for every technical proposition but as regards showers should have a regulation regarding min earthing conductor size.

There is.
You can calculate it to ensure it does not melt in the event of a fault before the supply is disconnected.
 16 April 2017 11:46 PM
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geov

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Spin, can you reference your comment that Beama do not regard an rcd fused spur as suitable to provide (additional) protection to fixed wiring.
Regards.
 17 April 2017 04:14 AM
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spinlondon

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Yes, this information can be found in the Beama RCD handbook, table 2.
http://www.beama.org.uk/asset/...4870-A9ACFBC5C58A94A2/
 17 April 2017 08:08 AM
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weirdbeard

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Originally posted by: spinlondon

Yes, this information can be found in the Beama RCD handbook, table 2.

http://www.beama.org.uk/asset/...4870-A9ACFBC5C58A94A2/


Beama member BG don't agree, see the note at the bottom of page 2 of the link:

"This product can also be used in "hard" wire installation. The blanking plug must be left in place, and the cable clamp is not used when there is no external flexible cable"



http://www.bgelectrical.uk/pub...ed_Connection_Unit.pdf

-------------------------
:beer)
 17 April 2017 08:09 AM
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alancapon

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I read that table differently. I understood it to say that fitting an RCD fused spur cannot be used to protect the fixed wiring, which I believe it to refer to the fixed wiring before the fused spur.

Regards,

Alan.
IET » Wiring and the regulations » 13amp fused RCD

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