Wiring for bathroom refit

[mshorthose]

Hi All,
I have spent the last seven years aboard a narrowboat where I was free to tweak the electrics in all sorts of unorthodox ways!
Now that I am back on land - and about to refit a bathroom - I need a few pointers on where to start (properly!).

Apart from halogen lights, there is no power in my bathroom at all.
I have just ordered a steam/shower/whirlpool bath affair which will need electrics running to it.
While I am at it, I propose to have two towel rails which will be electric.
The largest power consumer I think is the steam generator at 3.8kW - so not a huge demand.
I am guessing that a new circuit is required back to the consumer unit so I propose to channel in the cables, connect the sockets and then get a qualified electrician in to check and connect it at the consumer unit end (through an RCD or whatever is recommended).

Two questions therefore...
1) Will I need two circuits - one for the shower and one for the towel rails?
2) What size cable should I be using from the outlets back to the consumer unit?

A third one springs to mind...
3) Where do I get the towel rail outlets from?
Mum's is connected to a wall plate with a fuse and a hole in the front through which the cable passes from the wall to the heater.
I cannot find these on screwfix or in DIY stores.

Thanks for your help in advance

Martin

 

[i_am_fubar]

While I have nothing but contempt for part P's "incompitent till proven otherwise" philosophy. I would strongly advise that if you've been 'tweeking' electrics for a while, it may be best to get a profesional in, at a minimum for a consultaion. electrisity and brick, wood, stone, plater, all fine. electrisity and water.... much, much bigger risk.

 

[mshorthose]

Having been aboard a narrowboat, I am reasonably well aware of the hazards of mixing electrics and water!
Yes, I did have 240v on board, from a large inverter and enough 12v batteries to throw you over a hedge if you got it wrong.
While I certainly appreciate your concern - which is why connection would be done professionally - I think I can manage the expensive bits.
The hard work is removing furniture, carpets and floorboards to get to where the cable(s) will go, drilling holes through walls and chiselling channels - and then making good afterwards.
The question is, how many holes to drill and how big...
What size cable and how many runs.

 

[Qedelec]

While I understand your desire to save money, there is a huge difference between houses and boats apart from the obvious. For example holes in joists weaken the structure. Expecting an electrician to sign off your work is illegal and would you risk your livelyhood on someone you didnt know?

 

[mshorthose]

OK - I resign!
I am somewhat out of touch with regard to rules and regulations.
Mum had to have a council appointed chap round the other day to check that her replacement patio door had been equipped with the correct glass!
All of 30 seconds and £30 later...

I suppose someone has to try and legislate against idiots!
I take your point about the legality (or otherwise) of my proposal though - you know better than I.
I had considered holes in joints.
Try drilling a hole in the wrong part of a boat and getting away with it!

With all due respect - not all boat dwellers are imbiciles!
Boat electrics are hugely troublesome.
You have a mix of 12v and 240v for a start; no earth bonding to speak of and even then, the risks of galvanic corrosion of the hull.
Then you have a mix of sources to keep apart - a landline hookup, generator and inverter - which can kick in automatically if you do it right.

I have to say that my electrics on the boat were miles better than those in the house - right back as far as the supply, which given the number of times my lights at home flicker during the course of an evening is dreadful. I manage a number of UPS supplies for my IT network at the office and cannot believe what we put up with from the national grid.
At least on the boat I got a regulated 240v supply at the correct frequency!

Anyone want to tell me what gauge of cable I am using (for this to be legal) to that I can drill some holes?

 

[Qedelec]

I very much doubt that you are an imbicile, and I am sure in your own field you have to conform to the rule book.
As for the size of cable you will need for this work, you will need to calculate it based upon the load, route, length of run. There is more to it that just picking from a chart.
I am also sure you are not paid purely for the work you do but for the knowledge you have to do your work so £30 is not necessarily overcharging.

Regarding you comment about the lights flickering, I would strongly advise you contact an electrician registered with an approved body such as NICEIC as there may be a serious reason for this.

P.S. I had to resort to coming upstairs and typing this on my desktop pc as the mobile takes forever.

 

[mshorthose]

Thanks for making the special trip
I am still getting used to the idea of having stairs - and water that keeps going without refills, power that doesn't require engines to be run, heat that doesn't require coal or cooking without bottled gas.

Flickering at the same time every night looks to me like some sort of switching going on on the aforementioned national grid.
One area - within our county - holds a local record for 25+ power cuts in the space of two months.
By power cut I mean a glitch sufficient to reset clocks and timers - not outages lasting hours.
I had assumed there was nothing that could be done and that it was just down to aging substations.

Length of run is at the most 40ft, so I wasn't going to make much allowance for voltage drop or overheating (like I would on a 12v system). With only 3.8kW (allowing 5kW to include a safety margin, lights and so on) for the steam room, massive cable doesn't seem to be warranted.
I was thinking of erring towards 32A which should have enough capacity for two towel rails as well if that is allowed

Don't dash upstairs again unnecessarily...
I am going home now!

Thanks for now.

 

[i_am_fubar]

well. to be fair, if you have a REALLY nice multi dimensional chart.... you could just pick the cable sizes. (send me a link to one if you find one please )

The irony is. its illigal to do some wiring instalations... but building a 2,000,000 testla coil. No mention of that in the laws.

 

[ban-all-sheds]

The largest power consumer I think is the steam generator at 3.8kW - so not a huge demand.

But more than 13A..

I am guessing that a new circuit is required back to the consumer unit so I propose to channel in the cables, connect the sockets and then get a qualified electrician in to check and connect it at the consumer unit end (through an RCD or whatever is recommended).

The load is too great for a socket, and you probably don't want to work to the 17th rules that would allow you to have a socket in your bathroom, even if it's big enough.

Also, this work is notifiable, so if you intend to comply with the Building Regulations, just getting an electrician in to check your work won't do it...

Two questions therefore...
1) Will I need two circuits - one for the shower and one for the towel rails?

No. You might prefer that, or you might prefer to put the rads on a socket circuit, but you could have one circuit if you want.

2) What size cable should I be using from the outlets back to the consumer unit?

http://www.kevinboone.com/cableselection_web.html

A third one springs to mind...
3) Where do I get the towel rail outlets from?
Mum's is connected to a wall plate with a fuse and a hole in the front through which the cable passes from the wall to the heater.
I cannot find these on screwfix or in DIY stores.

TLC sell them.

But I would have thought they were widely available. Also look more closely at ones which appear not to have a flex outlet, as sometimes there's a little removable piece on the bottom edge, and the flex comes out there. (IMO that looks neater than a hole in the front anyway...)

OK - I resign!
I am somewhat out of touch with regard to rules and regulations.

See the Wiki.