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Topic Title: Shower Circuit
Topic Summary: Advice on Installation of Shower Cicuit
Created On: 16 October 2010 08:08 PM
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 16 October 2010 08:08 PM
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12216

Posts: 45
Joined: 22 August 2010

Hi all
Please could anyone confirm if the following is okay.

I have been asked by a to install a shower circuit to an existing installation. The existing consumer unit, (which has no RCD protection)is at present using all of its ways and the customer wants to avoid the replacement of the existing CU if possible.

would it be correct to install a new circuit in either of the following ways.

1- To connect the existing supply tails & earthing conductor that at present feed the existing CU into henly blocks and then from these reconnect to the existing CU and fit new tails from the henly blocks to a new RCD protected 2 way consumer unit to supply the new shower circuit.

2- To free up a way in the existing CU by removing the lighting circuit. installing an appropriate MCB in its place and from this feed a new RCD 2 way CU and reconnect the lighting circuit and install the new shower circuit.

Any advice or guidance greatly apprciated

Regards

Martin
 16 October 2010 08:19 PM
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mikejumper

Posts: 1803
Joined: 14 December 2006

Originally posted by: 12216
2- To free up a way in the existing CU by removing the lighting circuit. installing an appropriate MCB in its place and from this feed a new RCD 2 way CU and reconnect the lighting circuit and install the new shower circuit.

This sounds like the easier of the two options.
You could also have 2 RCBO's instead of one RCD.
Why not make it a 4 way CU to allow for additional circuits that might be required in the future.
 16 October 2010 08:27 PM
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12216

Posts: 45
Joined: 22 August 2010

Originally posted by: mikejumper

Originally posted by: 12216

2- To free up a way in the existing CU by removing the lighting circuit. installing an appropriate MCB in its place and from this feed a new RCD 2 way CU and reconnect the lighting circuit and install the new shower circuit.



This sounds like the easier of the two options.

You could also have 2 RCBO's instead of one RCD.

Why not make it a 4 way CU to allow for additional circuits that might be required in the future.


May go with the RCBOs makes sense.

Many thanks for your help
 16 October 2010 08:31 PM
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PatHammond

Posts: 219
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Remember that if any of the circuits in the bathroom don't have RCD protection then you need to make sure all the supp bonding is up to regs

-------------------------
4.5 day wonder...had to start somewhere
 16 October 2010 08:37 PM
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12216

Posts: 45
Joined: 22 August 2010

Originally posted by: PatHammond

Remember that if any of the circuits in the bathroom don't have RCD protection then you need to make sure all the supp bonding is up to regs


will put the existing bathroom lighting circuit on one of the new RCBO protected circuits off the new 4 way RCBO CU which should cover this

Regards
 17 October 2010 06:41 AM
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normcall

Posts: 8164
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Don't forget to notify both LABC (Part P ) and the electricity supplier (add load >3Kw) prior to carrying out the work.

-------------------------
Norman
 17 October 2010 10:34 AM
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daveparry1

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(add load >3Kw)
-------------
Does that still stand Norm? I hadn't heard it mentioned for years until a few day's ago on here, in fact I think it was you that mentioned it then,
Dave.
 17 October 2010 10:35 AM
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leckyles

Posts: 216
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2- To free up a way in the existing CU by removing the lighting circuit. installing an appropriate MCB in its place and from this feed a new RCD 2 way CU and reconnect the lighting circuit and install the new shower circuit.

What would the appropriate mcb be ?
Would fault discrimination be acheivable ?
Would a cartridge fuse not be required in place of the mcb in the c.u.?


leckyles.
 17 October 2010 03:28 PM
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12216

Posts: 45
Joined: 22 August 2010

many thanks all, for input on this one and advice,

ref installation of all equipment, fully competant in ensuring all the work will be carried out in compliance with BS7671 and all the regs relating to the install and the nofication process,

although ref the >3kw on the supply, will look into this for my own referance as not come across this one before. I was always under the impression that what ever the additional load is to be added to an existing installation, an assessment of Max Demand should be established first to ensure safe operation of the new circuit and to ensure that the existing installation is not comprmised .

may be i should have mentioned that i have yet to do a site visit to carry out assessment of the existing installation and the proposed installation of the shower circuit and therefore

Many thanks again to you all for your help on this one

Regards

Martin
 17 October 2010 04:24 PM
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ant1uk

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Originally posted by: normcall

electricity supplier (add load >3Kw) prior to carrying out the work.


I don' t think they will be interested, you wouldnt tell them your having a cuppa would you? unless you go over the max demand why would they need to know.

Regards
 17 October 2010 06:28 PM
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normcall

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Fixed load needs notifying. Kettles are not generally fixed appliances.
Naturally no one actually admits to adding load in case the REC decides your 10Kw shower/electric boiler needs network reinforcing.

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Norman
 17 October 2010 06:42 PM
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ant1uk

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I didn't know that, In any case I'm sure its down to the client to tell their supplier

Regards
 18 October 2010 07:18 AM
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ebee

Posts: 5781
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folk used to look at me like I got two heads when I applied for an additional load for a shower

I suspect not many use the correct procedure

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

Knotted cables cause Lumpy Lektrik
 18 October 2010 01:26 PM
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AJJewsbury

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Would fault discrimination be acheivable ?

Agreed - discrimination between MCBs is pretty impossible, whatever their ratings, (unlike good ol' fuses where 2x In rule of thumb works fine - maybe less than 2x if both fuses are of the same type).

Discrimination between MCB and upstream HBC fuse is possible, but you usually need a pretty high rating fuse.

I'd probably go for option 1 - but with a D.P. isolator thrown in upstream of the henleys for good measure.

- Andy.
 19 October 2010 08:41 PM
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leckyles

Posts: 216
Joined: 16 May 2007

Originally posted by: AJJewsbury

Would fault discrimination be acheivable ?


Agreed - discrimination between MCBs is pretty impossible, whatever their ratings, (unlike good ol' fuses where 2x In rule of thumb works fine - maybe less than 2x if both fuses are of the same type).



Discrimination between MCB and upstream HBC fuse is possible, but you usually need a pretty high rating fuse.



I'd probably go for option 1 - but with a D.P. isolator thrown in upstream of the henleys for good measure.



- Andy.


In agreement with you on that andy !


Leckyles
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