Hi I am about to fit a new bathroom suite,and there will be some changes to the wiring. I will be fitting a extractor fan in the loft space which is 23watt,and an aqualisa digital shower under the bath which is 150watt on boost.

I have used the equation Amps= Watts / Volts
(Watts 150 + 23 = 173) / (Volts 240) = 0.72 Amps

Could someone please look at the attached diagram and tell me if this is correct.I am planning on getting an electrician in to either carry out the job or inspect due to building regs.

Thanks
Jon

You are going to use an electrician who is a member of a scheme to comply with building regulations so why are you asking these questions?
1) Three lamps in series is unlikely to give desired effect unless you want really dim lighting.
2) Why have a pump and fan switched with lights?

Taking the fan first if it's needed for building regulations then having a window and if that window will open will alter how it needs to be wired. In most cases a pneumatic timer switch will comply but if you have a window linking solely to lights will not. You must be able to work fan without switching on lights, Unless the window opens in which case fan not required anyway.

Again pump. Most bathrooms contain more than just a bath and likely you would want lights without the pump running and also running pump dry likely to cause damage so again some re-think required I would assume.

At to law there are two ways to comply. Get an electrician who is member of a scheme. Or pay the LABC their fee. There is not an option of doing work and getting an electrician to sign it off that can only be done by the LABC who to my mind ask for silly money to check your work.

The reason I am asking these questions is, I have had three quotes to carry out these works already, ranging from £300 to £800. Every electrician that has come has had a different way of doing it.One chap wanted to install three pull cords in the bathroom one for each item, I thought this was a bit excessive. I am an aircraft electrician by trade, but don`t understand all the household regs. So thought I would design the circuit, then when electricians come to quote, explain this is what I would like, How much will it cost.

1) My mistake have corrected the diagram to show the lights in parallel.

2)The shower,fan, and lights only come on together, when someone is having a shower.The fused switch would normally be off, unless a shower was being taken.

So when I want a shower I would turn the fused switch on outside the bathroom door. Enter the bathroom and turn the lights on. This would turn the fan on, and apply power the the shower unit(In the first post I explained that the shower is an aqualisa quartz digital,thus applying power to the unit doesn`t turn it on.It has its own low voltage/data cabled wall switch.)

The bathroom has an opening window which does not provide enought ventilation, thus the reason of having a fan.

Hope this has cleared up the reasons behind laying it out like this.My main concern was running the shower and fan from the same 3AMP supply.
Thanks again
Jon

You won't always want to switch on the lights when you have shower (mid summer daytime, perhaps). I think you can get away with 1 pull cord and the Aqualisa power/data switch only, as follows:

1. Use the pull cord to switch on the lights only. Standard wiring.

2. The shower data switch is ultimately controlling the 230V supply to the shower pump. I have one myself. So, you could consider opening up the pump housing and, at the terminals for the motor, connect a parallel "switched live" supply to the vent fan via a "maintenance" FCU adjacent to the pump under the bath or the fan in the loft, whichever.

This would be in addition to the normal discrete FCUs for the shower controller and fan as per the MIs

Job done.