Bath Switch

[dabaldie]

Further to other questions i've asked... I'm fitting a whirlpool bath.. yes using RCD etc..
but I know that you must have an external switch for a shower (10.8kw), do i need one for the whirlpool? I've been told that the bath draws 3A, 5A at startup. Also with the cable under floorboards what cable size would you use? 2.5mm? or can i use smaller?... i've got loads of 1.5mm cable around.

 

[ban-all-sheds]

Use a DP switched FCU, 5A fuse - that will give you the isolation control that you need and allow you to use 1.5mm² cable on the load side.

 

[dabaldie]

but do i actually need a fcu?

the bath will be connected to a shower consumer unit RCD protected(with 10A MCB feeding the bath and a 50A connecting to a shower ) which will then be connected to a main consumer unit with a 50A MCB which is in turn protected by a 100A incomer.
surely if i want to isolate it i could trip the RCD, the 10A MCB, the 50A MCB in the consumer unit or even the 100A incomer..or all 4 to be really safe!!!!

i could always drop the 10A MCB to a 6A to protect the cable to the bath.?

 

[Steve]

No, you need an FCU, think about it. If something goes wrong with that bath, it could draw a lot of current which its circuitry probably isnt designed for, so you need a 5A rated fuse in a FCU. Also, like the shower and your cooker and all other appliances, you want local isolation, and i think this is also a requirement, especially in bathrooms. Just fit a FCU outside the bathroom in the hallway. Really, these things should be turned off when not in use. But then who pulls the cord after they've finished a shower?

 

[ban-all-sheds]

No, you need an FCU, think about it. If something goes wrong with that bath, it could draw a lot of current which its circuitry probably isnt designed for, so you need a 5A rated fuse in a FCU.

Depends what the makers say - it might be perfectly OK to use a 6A MCB. (BTW, dabaldie, 10A is fine for 1.5mm²).

Also, like the shower and your cooker and all other appliances, you want local isolation, and i think this is also a requirement, especially in bathrooms. Just fit a FCU outside the bathroom in the hallway. Really, these things should be turned off when not in use.

With protection (possibly) elsewhere, a pullcord in the bathroom might be preferable. Who knows.

But then who pulls the cord after they've finished a shower?

I do, and so do all the others in our house, otherwise the extractor fan runs for ever....

 

[Steve]

BAS, I guess pulling the shower switch a habit thing, we never got into it. My parents dont either. Our shower even has a red light on it that stays on as long as the power supply is on, its on all the time!

Do you have the fan wired into the shower switch? I never thought about doing that, how does that work then? FCU and fan isolator on shower circuit i guess? Or did you mean the light switch?

a pullcord in the bathroom might be preferable. Who knows.

As long as its not right next to the light switch, the person having a bath may end up in complete darkness! This would also mean running the cable into the roof space, then back down to the bath. More trouble than its worth i think!!!!

 

[ban-all-sheds]

Do you have the fan wired into the shower switch? I never thought about doing that, how does that work then? FCU and fan isolator on shower circuit i guess? Or did you mean the light switch?

The fan is controlled by the shower switch but supplied by the lighting circuit. I did it that way using a contactor to get round the problems of having to fuse down from 50A to 3A, and get multiple 10mm² cables into the switch.

See all the gory details here: //www.diynot.com/forums/viewtopic.php?p=123601#123601