Electric Shower / isolator switch issue

[Salty1969]

Hi guys,
I'm usually happy to turn my hand to most DIY but when it comes to electrics, that stuff can kill you, so I tend to just pay the money and leave the risk of any serious injury to the qualified pros like yourself.
Here's the story..
18 months ago we had a new electric shower fitted and was told at the time that we'd need to have an external isolator switch. "No problem, do what you need to do". Shortly after, job done, they fitted our Mira Sport Max 10.5 (which is a complete gimmick and nowhere near as sporty as they make it sound. If anything, I've put weight on since we've had it) and they fit a nice box with a shiny red switch in the nearby airing cupboard.
One month ago, my wife went to use shower, hit the button, no power? After shrieking at me and interrupting the football, I swore under my breath, pulled a face, huffed and puffed and stomped upstairs. First things first, I tried pressing exactly the same button (in case she's 'pressed it wrong' of course) Well, she was only right! no juice!
Being a forward-thinker, I went to the airing cupboard, switched the isolator switch off then back on...."try it now".......and the shower worked ok. I'm now an electrical superhero as well as a Billy Bookcase genius.
Fast forward 2 weeks and it happens again, so I switched isolator off then back on and shower worked ok again. Superhero status assumed.
Last week, every 2/3 days or so it would happen again......now the whole family is an electrical guru and now know to do the naked walk of shame across the landing, flick the switch off then on if it happens.....
Now we're at the stage where none of us can shower without flicking the switch first.
My superhero senses tells me that 'something's busted somewhere'. (I think that's the technical term)
I speak to the plumber who kindly gives me the spark's number who fitted it. I message him a week ago and he doesn't reply. I ring him after a couple of days and leave a message and he doesn't answer. I'm being ghosted by an electrician - I don't think he wants to be my friend. Tradesmen eh? tut, tut. All the same.
Today, I go to flick the switch and it looks as though that's now cream crackered as it is 'stuck' in the 'on' position. When I say 'stuck, we can still flick to 'off' but it now springs back to 'on', like it's tripping? (shower still works after doing this by the way)
In short, ANY advice or guidance would be greatly received before I pay another £80 call out for something that might cost £4.50. Not entirely sure it's helpful, but here's a picture of the switch and one of my dog in case anyone else loves Staffordshire Bull Terriers.

Thanks in advance, DIYers. x
Salty.

 

[fourtytwo]

First thing is find the circuit breaker for the shower in your consumer unit and turn it off!!
Second, find a DIFFERENT electrician and ensure they are qualified.
Something looks fishy not just with the isolator but also the cable, it doesn't look big enough for a 10.5Kw shower to me!
It may be loose wires have been arcing in the back and overheated the contacts (that may be to small anyway), in any case at present it is a fire risk.

 

[terryplumb]

Tell us the amperage rating of the Circuit breaker that protects the shower circuit.
And embossed on the cable you should find the size of the conductors ,tell us what they are too.
Are you intending to fit a new switch yourself ? If so ,you need to be aware of exactly what type to buy.

 

[Salty1969]

Thanks both for prompt replies.
@fortytwo - No overreaction? This could be a fire risk? Obviously a lot more serious than I expected and absolutely seething with the electrictian if this is the case. Plumber is realjy good friend of mine, so assuming he wouldn't use a cowboy??? Have turned off main fuse already but now we're a family of 4 without a shower! So that needs sorting ......today.
@terryplumb, I'm so sorry, but i dont know what all that means. wouldn't have a clue. Nothing embossed on the cable from the top to bottom of the airing cupboard anyway.
Oh, boy.

 

[chivers67]

Looks 6mm T&E to me, sounds like a New switch is required. On the side of the insulation there should be some printed writing indicating the size of the cable

Look here

see the markings on the insulation? Try finding the size or take a photo.

Nice Dog by the way!

 

[terryplumb]

What don't you understand ? Surely not my question asking if you intend to fit a new switch yourself ?
Your fuseboard or consumer unit will have a fuse ,or a circuit breaker that protects the shower circuit, you state you have " turned off the main fuse" ,show us a pic of that.
As said above the cable should have identification on it.

 

[RandomGrinch]

I think I would also prefer a 50A switch to a 45A one, on a 10.5kW shower...

 

[Salty1969]

Looks 6mm T&E to me, sounds like a New switch is required. On the side of the insulation there should be some printed writing indicating the size of the cable

Look here

see the markings on the insulation? Try finding the size or take a photo.

Nice Dog by the way!

Thanks chivers67.
If the mm relates to the thickness, its more like 10 or 12 if that's a thing. No printing on the cable though? Trying to get a torch on it.

 

[Salty1969]

What don't you understand ? Surely not my question asking if you intend to fit a new switch yourself ?
Your fuseboard or consumer unit will have a fuse ,or a circuit breaker that protects the shower circuit, you state you have " turned off the main fuse" ,show us a pic of that.
As said above the cable should have identification on it.

Genuinely sorry to frustrate. I certainly don't intend to fix this myself, especially if it's a fire risk.
Here's what I've turned off.

 

[terryplumb]

Thanks ,that is a 45amp RCBO,which is ok for a shower circuit ,providing the cable size is also suitable.
Not doing anything yourself ,but bringing in an electrician would make sense.

 

[EFLImpudence]

If the mm relates to the thickness, its more like 10 or 12 if that's a thing.

It's doesn't. it relates to the cross sectional area of the wires - square millimeters.

Anyway the cable looks bigger than 10 or 12 mm.

Looks like 6mm² to me, which might be alright depending on where the cable runs.

 

[robinbanks]

If the mm relates to the thickness, its more like 10 or 12 if that's a thing. No printing on the cable though? Trying to get a torch on it.

It relates to the cross sectional area of the copper conductors inside the cable. The markings on the cable could be embossed or engraved (i.e. in the same material as the sheath is made of, so just feeling like bumps) rather than printed in a different colour, like this:

It sounds like you've potentially got some fault in both the shower (because it needs "rebooting" before it will work, though they're really not very smart devices) and the switch, but as the switch has dropped to bits internally and is the cheaper thing to replace it'd be wise to start with that.. And maybe it'll turn out that it's underrated, its contacts have suffered some malady that means they have to be broken and re-made to give good power to the shower, because they're arcing/burning, and replacing it with a different switch will solve the rebooting thing too..

 

[chivers67]

Thanks chivers67.
If the mm relates to the thickness, its more like 10 or 12 if that's a thing. No printing on the cable though? Trying to get a torch on it.

The Embossed printing is only on one a side.

(Cheers Robin i was looking for a better image)

 

[JohnW2]

Anyway the cable looks bigger than 10 or 12 mm.

It does - I would say (from photo) that it is about 15.5 mm wide.

Looks like 6mm² to me, which might be alright depending on where the cable runs.

Maybe - but per ("my" ) table from the wiki you posted, 15.5 mm (if that's what it is) is fractionally closer to the tabulated figure for 10mm² than 6mm² -= so who knows?!

Kind Regards, John

 

[EFLImpudence]

Really? Surely 14 is nearer 13.5.