Electric shower cuts out after 5 mins

[CrazeUK]

Hi all.
I have seen similar topics on the forum, but not the same as my experiences.
I have what I think is a Mira Go 8.5kw shower (maybe it's a 9).

It seems to run fine for about 5 to 10 mins, then trips the RCD. When you switch it back on, ots runs for another 3 or so mins then trips.

When it trips there is no change in the water temperature.

Yesterday I did hear the Fuse box making a very low buzzing noise after a short while of being the shower on.


Do we suspect a problem with the Rcd or the shower?

 

[jj4091]

If you have an isolator on the wall or cord pull I would check that for loose or burnt wires first.

 

[CBW]

Sounds like it could be the rcd.

 

[CrazeUK]

I do. I will open it and check the isolator.

Sounds like it could be the rcd.

Should I just replace it? Is there any way to tell if there is wear / damage or test it,outside of a visual inspection ?

 

[bernardgreen]

Are you sure it is the RCD ( this has a test button ) that is tripping and not the MCB. ?

the Fuse box making a very low buzzing noise

which suggests an MCB is being overloaded and its magnetic trip is close to tripping

It seems to run fine for about 5 to 10 mins, then trips the RCD. When you switch it back on, ots runs for another 3 or so mins then trips

which suggests that the thermal trip in the MCB has after 5 to 10 minutes become hot enough to trip the MCB, The shorter trip time after switching back on will be due to the thermal trip mechanism still being hot from the previous trip.

 

[CrazeUK]

Maybe I am being confused (not an electrician).

It is one of these

(not my actual box)

 

[terryplumb]

Show us a pic of your actual consumer unit and indicate what exactly trips.
The pic you have shown is of no use at all.

 

[CrazeUK]

Show us a pic of your actual consumer unit and indicate what exactly trips.
The pic you have shown is of no use at all.

 

[CBW]

That’s an mcb (miniature circuit breaker). The big one to the right labelled RCD is as you would expect the RCD (residual current device).

 

[CrazeUK]

That’s an mcb (miniature circuit breaker). The big one to the right labelled RCD is as you would expect the RCD (residual current device).

Oh my bad.
It's the MCB that trips then.

 

[terryplumb]

Thanks ,but need to know the amperage of that MCB.
It will have B20 ,or B32, or similar printed above the lever. What is yours ?
Just realised it's 32 amp.

 

[CrazeUK]

Does this mean I need to get a higher amp MCB for it?

I have only opened the consumer unit once to replace one of the other MCB's. Is it legal for me to replace or do i need to get a qualified electrician to do it?

 

[CBW]

Oh my bad.
It's the MCB that trips then.

Still could be the mcb, if it’s making noise.

 

[CBW]

Thanks ,but need to know the amperage of that MCB.
It will have B20 ,or B32, or similar printed above the lever. What is yours ?
Just realised it's 32 amp.

Is it not the same as the printed one at the bottom then?

 

[CrazeUK]

I'll get the numbers shortly.
When I put my ear to the box it was the mcb for the shower that was making the noise.