Changing a Switch from a 32 amp to 45 amp on a MCB

[andrewjohnsimpson]

I had a shower installed a Mira 10.8kw with new 10 mm cable. Everything is fine apart from one thing. The shower trips out when it is being used for a while.

I have called Mira and they said that I need a 45 amp trip switch not the 32 amp trip switch that is installed.


My question is

It looks easy to change over the switch, it is okay for me to change a 32 amp to a 45 amp trip switch myself?

Or

Should I just get an electrician in for it?

Untitled

• andrewjohnsimpson
• 5 Oct 2010
• 1

Untitled

• andrewjohnsimpson
• 5 Oct 2010
• 1

 

[mfarrow]

I'm surprised no-one has answered, but I suspect that it's only because the answer is not one you'll like to hear.

Changing the trip, easy (ish) in theory, but it's likely your cable to the shower may not be up to the increase in load (the breaker protects the cable, not the shower itself).

Get an electrician in to see what they think. Is the cable route accessible? Can you make it so? Anything will help really if he ends up replacing it. Otherwise it's a new shower I'm afraid.

 

[ban-all-sheds]

• http://www.tlc-direct.co.uk/Book/6.1.1.htm
  
  
• //www.diynot.com/wiki/electrics:mcbtocable
  
  
• http://www.tlc-direct.co.uk/Book/4.3.1.htm
  
  
• http://web.archive.org/web/20080213151445/http://www.kevinboone.com/cableselection_web.pdf
  
  
• http://www.tlc-direct.co.uk/Book/5.3.1.htm
  
  
• http://www.tlc-direct.co.uk/Book/4.3.11.htm
  
  
• http://www.tlc-direct.co.uk/Technical/Charts/VoltageDrop.html
  
  
• http://www.tlc-direct.co.uk/Book/8.1.1.htm
  
  
• //www.diynot.com/wiki/electrics:part-p
  

 

[pjcomp]

Ditto - as far as cna be judged from your picture, your shower cable is 6mm. For your 10.8kW shower you'll need a 10mm cable.

PJ

 

[andrewjohnsimpson]

It has the right cable as the electrician installed it, I think he just didn't look at how powerful my shower is?

 

[ban-all-sheds]

Then how do you know he didn't install a cable suitable for a 32A circuit rather than a 40A one?

Mind you - if you told him you wanted a shower circuit, even if you didn't tell him what size shower you were having he did a p***-poor incompetent job by short-sightedly installing one limited to 7.6kW...

 

[RF Lighting]

If that cable is bigger than 6.0mm² then I'm a monkeys uncle.

 

[sparkwright]

You would be wise to confirm if the cable is 10 mm first.

As for changing the MCB, it depends how competent you are to do so.
Those Crabtree breakers click in, rather than screw in, so a certain knack is required.

It may be sensible to get the installer back (if you have confidence in him), find out why the MCB isn't rated to match the shower, and find out what size cable that is.

You may be able to obtain some off cuts of both 6 and 10 mm cable from a DIY shop, and then compare to the shower cable.

 

[ban-all-sheds]

It may be sensible to get the installer back (if you have confidence in him), find out why the MCB isn't rated to match the shower, and find out what size cable that is.

It'll have the size on the EIC....

 

[1john]

Thas is 6mm csa, no way in the world is it 10mm! uprating the breaker will make that cable run hot or even catch fire depending on how it is routed.

 

[Taylortwocities]

It'll have the size on the EIC....