Shower- new CU or can I free up space on the existing one?

[ABCwarrior]

Right folks, bear with me!
2 yr old house, no space left in the Wylex CU to add a MCB for a shower-
From R-L it reads
Main (RED) RCD Switch:1-Cooker 2-Immersion one 3-Heating 4-Bell+Smoke
From there there's another RCD that controls: 1-Utility+Downstairs Bed Sockets 2-Upstairs Sockets 3-Downstairs Lights
From there there's another RCD that controls: 1- Kitchen Sockets and Lounge 2-Upstairs lights 3-Immersion two.

How could I go about fitting an instant shower when there's no more room at the inn so to speak?
I don't get the "Heating" one- we have two immersion elements, hot water is also provided by a solar panel and a multifuel stove- maybe it's the solar stuff?
There's physically room on the board(plywood one) to put in a Henly block and a new CU, but I know under current law I can't legally do this...

In my last flat I plumbed in and wired in the shower, this included "retrofitting" the CU to take a newer MCB(had to cut the busbar etc add a wire to the main supply to connect to the more modern MCB which was physically bigger than the old ones, was a few yrs ago but worked perfectly.
To free up this space for the shower(40A) MCB I had to "splice" the wiring for the fridge and washing machine into one MCB, both had minimal draw combined so there were no issues and I marked the CU clearly.

So, on that note could the bell and smoke circuits be combined and jacked into another MCB or is this just a no no these days?

A sparky I worked with recently said all new builds in Scotland should have 25% spare capacity in the CU....
A new CU/Block looks by far the easiest and neatest solution- what grade of wiring would be correct? 16mm2 or 25mm2

Any advice appreciated- If it needed a new CU then I need to get it done legally or my house insurance is invalid- but if I fit the shower to the wall, plumb it, and then make all the route clear to run the 10mm T+E from the CU how long should a competent sparky take to make the connections etc? we're talking a run of 6m through one stud wall.

Ta!!!

 

[PrenticeBoyofDerry]

Really you should not be mixing MCB makes in CUs, as they are type tested for the board. So you really need to use the right MCBs in your board, the one the boards is manufactured to use and has been tested with, mixing them could to cause you difficulties with validation of insurances, if a problem arises from them.
Your easiest way around this without compromising the CU and other circuits is to install a shower unit
If you are expecting an electrician to inspect, test and cert this, I suggest you get one on board before you go any further and take the advice they offer, as they will be able to take a more of an informative approach after actually seeing the the installing in real terms.

 

[ABCwarrior]

Thanks for the reply PBOD- I take it that CU is a decent make then?
The missus has just informed me our neighbour(exact same house) has had an instant shower installed- best bet is to "spear" them for who did it, how much it was etc, but she's also said their sparky managed to drill through a water pipe while doing his bit resulting in some of their solid wood floor needing lifted to get to the pipe.
Hmmmm......

This is the reason I attempt most things myself!!!

(And thus from a very simple point of view I look at my CU and say- ok, F the electric company, neatly cut the security wire(so it can be replaced to look untampered with!) and remove the 100A fuse, remove tails from existing CU, put into Henly block, take new(16mmm) L+N tails to old CU, then same to new CU. Earth the new CU to the available space on the earth on the main 100A using same grade of earth cable- all within 150mm of each other on the board, so no distance issues. Then run 10mm T+E from the new CU to a switch on the board for the shower(cooker type, don't want an ugly drawstring and pattress in the shower room), 10mm T+E then run to the shower itself putting it in proper conduit all the way including through the stud wall. Connect to shower from top side and seal all gaps at shower/conduit interface with silicone to keep out moisture.... I know fully well I aint a sparky but this is surely well within the realms of an intelligent enough person- I'm a stonemason and have done up to HNC in Building)

One thing though- when we first bought the place I asked about putting in an instant shower, and the bloke from the trust we got it from said we couldn't as the transformer wasn't set to take this load? Anyway, after the first winter the multifuel stove was hopelessly not doing it's job regarding heating the water, so that's when they installed "immersion two" as a quick fix, so we could at least get some hot water in the whole tank, not just the top of the thermal store.
I'm assuming that these two immersions when on run 6kw(3 apiece?), and considering I've run two 2kw oil radiators simultaneously upstairs then as long as these items aren't on then a 9.5kw shower shouldn't have any problems? I'll ask the neighbours if they had any issues or had to consult the leccy company prior to this, or if their sparky did?

Don't be too down on me for wanting to do it myself, I've little faith in anyone else having seen the shocking state of the plumbing work, plastering, joinery and our ****ty "affordable home" has been left in such a state externally (tree stumps needing removed, no garden landscaping whatsoever) that I'm trying to save and divert cash wherever I can. Like spinning plates at times.....

 

[xr4x4]

Your just gonna do it yourself anyway aren't you...

 

[ABCwarrior]

Struggling to find a valid reason not to....and all I can come up with is the insurance angle
I do understand the complexities of modern electrics and the testing side etc- can't see many young sparkys getting apprenticeships these days without a maths and physics "o" level at least, but what I'm looking at isn't rocket science. Ten years ago I'd be battering on with it without a second thought.

Can anyone give a ball park answer to what an unqualified person is allowed to touch these days then?
At our work we're now barred from changing lightbulbs. Seriously. Frickin mental state of affairs H&S has brought us to.....

 

[ban-all-sheds]

Struggling to find a valid reason not to....and all I can come up with is the insurance angle

And that there are things you don't know. The problem with asking questions is that you'll only ask about the things you know that you don't know - you won't ask about stuff you have no idea even exists.

Pulling the supply fuse is a bad idea - to be strongly advised against. If you need the supply isolated to replace or add a CU you should get the supplier to come and remove, then later replace, the fuse.

I do understand the complexities of modern electrics and the testing side etc

So what will you do about testing?

 

[westie101]

ok, F the electric company, neatly cut the security wire

An action if discovered could render you liable to have your supply disconnected!

One thing though- when we first bought the place I asked about putting in an instant shower, and the bloke from the trust we got it from said we couldn't as the transformer wasn't set to take this load?

You do need permission from the DNO to connect a fixed load the size of a shower (and an immersion heater come to that). If use of the shower causes excessive voltage dips to your neighbours again you are liable to be disconnected!

 

[Taylortwocities]

(And thus from a very simple point of view I look at my CU and say- ok, F the electric company, neatly cut the security wire(so it can be replaced to look untampered with!) and remove the 100A fuse,

Wearing the correct PPE, I trust, you may need it

Untitled

• Taylortwocities
• 11 Jun 2011
• 8

 

[ABCwarrior]

Interesting about getting permission, may be anecdotal but since the neighbour had his shower commissioned two weeks ago we've had two power cuts...
I will ask him how much it cost to get the main fuse removed while the sparky did the work and how much it was to get the supply load increased(?!?!any tech term for this?)
Should be interesting to see what he responds with, not a very technical minded chap. I'll wager now that the sparky has just done the work and no-one has been notified at the DNO....
So we have a development of four houses presumably sharing the fixed supply from a nearby transformer- i assume the amount we get is set by the DNO, but does this mean then that if say, the neighbour has his immersions on, the shower going and a few oil filled radiators would this impact on the rest of us, ie could they be accessing more than their "fair share" and prevent something working properly in ours?

 

[westie101]

The amount available will have been agreed between the builder and the DNO at the time of installation, on large estates it doesn't matter as much but for 4 houses fed from one transformer it can be easy to overload the DNO assets

 

[ABCwarrior]

Cheers for that Westie- all of us are on a form of Economy 10 tariff too, 10hrs a day is off peak split into 3 time slots, and I'm damn sure that's the time when everyone's washing machines/immersions etc get used!!! There's no other houses nearby so pretty sure we have our own transformer dedicated to this place, so a few instant showers running at the same time may be enough to overload it then....?
Very informative this is proving to be....cheers!
If anything is going to stop me installing a shower "unofficially" this is it BTW!

 

[westie101]

As there is storage heating the transformer size will be large enough to take all of that load plus an immersion heater per house, there is often an allowance above that!.
In theory if the shower is used outside off peak times, or towards the end of them e.g. in the morning. There should be no problem.

From the standard transformer sizes I would make a guess that you should have 100A per house available - but only a guess!

 

[RF Lighting]

(And thus from a very simple point of view I look at my CU and say- ok, F the electric company, neatly cut the security wire(so it can be replaced to look untampered with!) and remove the 100A fuse,

Wearing the correct PPE, I trust, you may need it

Untitled

• Taylortwocities
• 11 Jun 2011
• 8

I wonder why he's pulling the fuse on load?

 

[EFLImpudence]

He's probably just an actor 'posing' as in a demonstration video I once saw where an 'electrician' was demonstrating how to remove a socket by turning the screws clockwise.

 

[westie101]

Aye as he should be wearing the leather protectors over them gloves!