10.5KW shower 10mm stud wall query?

Aaronj46 · Oct 11, 2018

So I have been working on a contract installing 10.5kw showers with B40 MCB's as specified by builders but occasionally a plot reports the shower tripping when having long showers. Hager don't do a 45A MCB but do a 45A RCBO but then its the cost....£££

The cable is ran in uninsulated studwork for around 9metres to the isolator and then around 4metres to go into loft and back down. Is there a way a I can justify a B50?

Any suggestions would be much appreciated!

Taylortwocities · Oct 11, 2018

What do your cable calculations say about having a B50 on the 10mm cable, given the installation method?

telectrix · Oct 11, 2018

who in their right mind wants a long shower? in, wet, soap, rinse, out for some beer. 5 minutes tops.

Taylortwocities · Oct 11, 2018

telectrix said:
who in their right mind wants a long shower?

My 16 YO daughter, for one. the Megaflo is 210 litres, but she can run it cold......

Spoon · Oct 11, 2018

I'm with Post #2...

telectrix · Oct 11, 2018

I,m with RBS.

Andy78 · Oct 11, 2018

Aaronj46 said:
So I have been working on a contract installing 10.5kw showers with B40 MCB's as specified by builders but occasionally a plot reports the shower tripping when having long showers. Hager don't do a 45A MCB but do a 45A RCBO but then its the cost....£££

The cable is ran in uninsulated studwork for around 9metres to the isolator and then around 4metres to go into loft and back down. Is there a way a I can justify a B50?

Any suggestions would be much appreciated!

Cost ? £20 to do the job properly ?

No idea as only you know the routes and installation methods and the derating factors involved.

Spoon · Oct 11, 2018

Taylortwocities said:
My 16 YO daughter, for one. the Megaflo is 210 litres, but she can run it cold......

Disconnect shower and tell her to have a bath... that will save you a bit.

Nigel · Oct 11, 2018

Shower room circuits should have RCD protection anyway.

Pete999 · Oct 11, 2018

telectrix said:
who in their right mind wants a long shower? in, wet, soap, rinse, out for some beer. 5 minutes tops.

Turn it on, run about for a bit you won't need a towel then, the builder specified the MCB let him sort it Mate, Although wonder how much he knows about electrics, probably specified from memory, oh that's what most shower installs consist of.

Spoon · Oct 11, 2018

Pete999 said:
Turn it on, run about for a bit you won't need a towel then

What are you doing??????? I now have an image of you all wet, running around naked.... I need a 'Delete' button....

telectrix · Oct 11, 2018

Spoon said:
What are you doing??????? I now have an image of you all wet, running around naked.... I need a 'Delete' button....

just send him an invite to survey the nursing home.

.

Wilko · Oct 11, 2018

Hi - what size are the conductors? If you're using 6mm then 50A is a definite no. If there's no faults, I'd replace the mcb and see if it stops tripping.

Taylortwocities · Oct 11, 2018

Wilko said:
Hi - what size are the conductors?

The title to the thread reveals this, I think…?

Spoon · Oct 11, 2018

Taylortwocities said:
The title to the thread reveals this, I think…?

or he has very thin stud walls.....

Wilko · Oct 11, 2018

Taylortwocities said:
The title to the thread reveals this, I think…?

Doh !

[ElectriciansForums.net] 10.5KW shower 10mm stud wall query?

Fitzy · Oct 11, 2018

Surely if the ‘builder’ specified the 40A MCB and that’s in writing in the design specs he gave you, then the builder is liable for the price of upgrading the MCB to a 45A RCBO. Just show him the cable/wattage calculations that show it needs the higher 45A MCB/RCBO, he then has no choice it to either downgrade the shower or upgrade the MCB/RCBO.

telectrix · Oct 11, 2018

going back to the OP. this is a cunning plot to save water. as we all know, i times of low rainfall the country runs out of water, no hosepipes, and let your car/van look like something out of afganistan. fair play to the designer being conscienscious about saving water.

Risteard · Oct 12, 2018

Aaronj46 said:
So I have been working on a contract installing 10.5kw showers with B40 MCB's

And how does this comply with BS7671?

Spoon · Oct 12, 2018

Risteard said:
And how does this comply with BS7671?

Because is has been "specified by builders" so it must comply.....

Toneyz · Oct 13, 2018

Does the existing consumer units have RCD protection with a spare way for the new circuit as it would be required anyway due to the circuit in bathroom and cables I presume within 50mm of the wall surface or metal stud work? Remember that with a standard 10.5kw resistive load shower you will not get overcurrent do your calculations based upon a B50 MCB.

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Toneyz

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