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Discuss Shower tripping mcb after being used in the Electrical Forum area at ElectriciansForums.net

Vwmon69

New EF Member
Hello. Can anybody please help. I've been in my house for 5 years and had no trouble with shower at all. A couple of weeks ago the wife says that shower wasn't working. I looked at circuit board and mcb had tripped. Flicked switch back on and everything was ok. Went for a shower later and its tripped again. Flicked it back on and it worked again. Thought shower might be knackered with being old so put a new shower in. 8.5kw with 32a mcb. Same problem.
I can flick mcb on and it will stay on, I can have a shower and it stays on, when I turn shower off it still works but a few minutes after I turn shower off it trips mcb. Any ideas off what the problem is will be greatly appreciated. Thanks
 

Bob Geldoff1234

Somewhere,somehow,someone's going to pay
Is it the same 32 amp MCB that you have always had? If it is then it could be getting tired.A 8.5kw shower can pull approx 38 amps which is stressing the 32amp mcb.Over time they get lazy and trip even more.I would recommend changing the mcb to a 40 amp and see how it goes.Don't forget that since Jan 1 ,the replacement mcb has to be the same make and model as the original.You can usually source one off Ebay if your local wholesalers doesn't have one.
 

wirepuller

Forum Mentor
Only thing I would add is go careful with Ebay as counterfeit goods are rife and are likely to be unsafe. Best to source from a reputable supplier. Also you cannot simply replace a 32a for a 40a without verifying wiring is still fault protected and disconnection time is still met.
 

Wilko

Electrician's Arms
Hi V and Welcome to the Forum!
I suspect you're going to need some help to fix this as it could be a wiring fault (is it mcb or rcbo?) or a tired mcb as per Bob.
 

Strima

Electrician's Arms
Before swapping the MCB for a higher rated one ensure your cable is suitably rated for the load after any relevant rating factors have been applied.
 
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Murdoch

Electrician's Arms
Whilst the advice on the mcb made be reasonable, who is to say the cable is big enough?

Unless you have competence and test kit, rushing to upgrade a mcb could have unpleasant consequences ....
 

wirepuller

Forum Mentor
Before swapping the MCB for a higher rated one ensure your cable is suitably rated for the load after any relevant rating factors have been applied.
As per you, S. First thought on reading OP.
It's a fixed load, changing the mcb for a higher rating will have no effect on overload protection, which is not required, only fault protection will be affected.
 

telectrix

Scouser and Proud of It
Respected Member
It's a fixed load, changing the mcb for a higher rating will have no effect on overload protection, which is not required, only fault protection will be affected.
agreed, but OP needs to determine if the cable is the correct size for the load, ref. method being taken into account.
 

Vwmon69

New EF Member
Thanks for the advice. I believe the current mcb is a Lewden one. Does that mean I have to get it swapped with another lewden. Why can i not use something like a Wylex if it's the same ampage
 

Murdoch

Electrician's Arms
Thanks for the advice. I believe the current mcb is a Lewden one. Does that mean I have to get it swapped with another lewden. Why can i not use something like a Wylex if it's the same ampage
Have you read post #7?

And no you can't fit any manufacturer .... some won't fit at all and we are now on the 18th edition which specially stops it
 

wirepuller

Forum Mentor
Thanks for the advice. I believe the current mcb is a Lewden one. Does that mean I have to get it swapped with another lewden. Why can i not use something like a Wylex if it's the same ampage
As above, it is now a departure from the regulations to fit a device from a different manufacturer, unless you want to be legally responsible for the design of your DB if a fire was caused.
 

ipf

Forum Mentor
It's a fixed load, changing the mcb for a higher rating will have no effect on overload protection, which is not required, only fault protection will be affected.
On about upping the cable size to suit the protective device, though.
 

Strima

Electrician's Arms
This could be wired in 2.5 for all we know.
 

wirepuller

Forum Mentor
On about upping the cable size to suit the protective device, though.
It's a fixed load, the load will be 8.5kw regardless of the rating of the protective device. Overload protection is not required, only fault protection.
 

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