shower unit

[gazza]

hi there i want to install a shower unit 9.5 kw am i rigt in thinking that i require a 45 amp mcb and 10mm twin and earth could you please tell me if this is correct

 

[Hamiltonandy]

Yes.
9.5KW is about 39.5A at 240V mains so you could use 40A or higher MCB. Use 10mm cable as 6mm only does 32A and 10mm rated up to 43A.
Might consider adding fused outlet next to shower pull switch so on switching shower it also switches shower light on.

 

[gazza]

would i need an rcd mcb or would a normal 45 amp mcb do

 

[Hamiltonandy]

If you are thinking of those combined units, I would avoid. If shower trips you would want to know reason. Also keep ELCB separate from MCB as more reliable. MCB protects cable from overload and ELCB protects you from shock. Shower people normally recommend 30mA ELCB now but this would supply power in consumer unit to several MCB. You really should have at least one ELCB covering your house. I use 100mA for kitchen to stop nuisance trips and 30mA ELCB for rest of house.
I would use 40A MCB as next available by QVS is 63A.

[Edited by Hamiltonandy on 10-11-2002 at 15:44 PM GMT]

 

[clifton82]

I have a separate fuse unit for my shower but when i switch the shower on the lights dim can anyone tell me why this happens.

 

[breezer]

its called voltage drop, there is too much current being drawn when your shower is switched on for your supply to cope.
its like saying there are two people and one apple and they both want it , so they have a piece each, (not half) but neither gets all of it

it can be cured by installing a bigger supply cable (but that is for your supply company to do)

if it is of any use where i used to live the same thing used to happen, (the lights dimmed slightly, i presume yours do the same?)

the other thing is how big is your shower (in KW) and what size (in mm)cable does it have