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

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

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

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4.5 day wonder...had to start somewhere

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

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

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Norman

(add load >3Kw)
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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.

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.

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

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

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

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

Regards

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

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Regards,
Ebee (M I S P N)

Knotted cables cause Lumpy Lektrik

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