Triton Spellbind shower tripping RCD

[cb1980]

Hi,

I moved into this house about a year ago. Shortly afterwards, when I had a lot of people to stay and so the shower was used a lot in a short time, the shower tripped the RCD.

Since then, the time before it tripping has slowly decreased to being within a long shower (~10 mins), and is now down to a couple of mins (I have to stop it while I lather up!). Whilst this is economical, it's a giant pain in the backside since the RCD is in the cellar.

Today I thought I'd narrow down the issue before posting on here.

I ran the shower for 10 mins on cold with no trip, then 10 mins on low with no trip. When I put the shower on high it tripped the RCD within a couple of minutes. So it looks like that might be the source of the problem.

The shower is a Triton Spellbind. I don't know what the power rating is, but I see the model comes in 9.5kW and 10.5kW variants.

Any ideas, or do I have to call an electrician?

Thanks

 

[JohnD]

it might be a water leak, which takes time to build up to enough to wet the electrical parts.

When the shower is in frequent use it does not have time to dry out between uses.

If you are ?lucky? it will be a leak inside the shower box, if you turn the power off you might be able to see e.g. a loose connection and tighten it up. the box may have a drain that is blocked, but preferably no water should be able to get in.

This needs great care as water and electricity are best not mixed, especially with fingers.

It could also be that the heating element is breaking down with age, and causing earth leakage. Heating elements tend to do this (also in ovens)

Electric showers are fairly cheap to replace and often not worth trying to repair.

A few photos (cover on/cover off) will give clues.

 

[cb1980]

Thanks, I'll have a look and get back to you.

 

[Steve]

And its definitely the RCD (large switch with a test button)

not the MCB (smaller switch)

 

[daytona]

it could also mean its been wired out in a cable thats too small and its now damaged.

slowly been cooked so to speak

 

[cb1980]

Sorry, RCD was probably the wrong word...

It's the fuse switch for the shower on the consumer unit.

Shot of the cable here.

I haven't had a chance to take the cover off of the shower yet.

 

[cb1980]

Oh, and it's the fuse marked "B50" with "shower" written below that trips.

 

[experience]

Thats a circuit breaker not an RCD - circuit breakers will only trip in fault conditions i.e. overload of short circuit.
So it will either be a break in the cable so the live/neutral/earth cables are touching somewhere because the cable is damaged or the shower is overloading the circuit.

It looks like you've got 10mm T&E but its hard to tell from the pic-personally i'd have put that on a 40a breaker to protect the cable from overheating and cooking as previously mentioned, but that depends on the size/length of the cable.

Inside the breaker is a thermal coil that as it gets hotter expands and causes the breaker to trip to protect the circuit - this could be damaged so you can try replacing the breaker for a few pounds.

Really you need to get a sparky in as they've got the test equipement and can check the insulation of the cable to see if it is damaged, and to check how many amps the shower is actually pulling.

 

[RF Lighting]

It only looks like 6.0mm² to me.

That CU looks reasonably new, so I'd have expected to see an RCD for the sockets and shower.

@ OP, did you manage to find out the power rating of the shower?

A pic of the shower with it's cover off would be a big help.

Is there a DP isolator somewhere for the shower supply?

 

[cb1980]

Thanks for all your responses. I'll try to answer as much as possible...

Shower with the cover off here.

Looks like it's a 9.5kW model by the label.

Hopefully this will help you identify the cable.

I don't know exactly what a DP isolator is... To me it looks like there's just the circuit breaker on the consumer unit and a red-button switch (like a lightswitch, so I doubt it's anything that technical) outside the bathroom.

 

[luminaire]

Hopefully this will help you identify the cable.

Definitely 6mm² cable.

 

[experience]

A 9.5Kw should be on 10mm cable with a 40A breaker or even a 32A if poss taking diversity into account.
6mm on a 50A breaker will have melted the cable as its undersized
Using that shower on a 6mm is a fire risk!
Run a new 10mm cable from your consumer unit to the shower and downgrade the breaker.

 

[cb1980]

The bathroom is only a few years old, with tiled walls and floor, so there's no way that I can re-wire it.

I think the only possibility is to replace the shower with a less powerful model...

You can imagine just how much I want to strangle the previous owners right now. How could they have been so stupid? Grrr!

 

[Softus]

Shower with the cover off here

Thoese incoming (old colour) conductors don't look anywhere near big enough to me. More like 2.5 mm² than anything else.

Hopefully this will help you identify the cable.

Is that photo taken at the CU, or near the isolator switch, or the shower?

I don't know exactly what a DP isolator is... To me it looks like there's just the circuit breaker on the consumer unit and a red-button switch (like a lightswitch, so I doubt it's anything that technical) outside the bathroom.

Could you post a photo of that switch?

I think the only possibility is to replace the shower with a less powerful model.

If the cable is already cooked then you're too late - replacing the shower won't eliminate the fire hazard.

 

[JohnD]

The bathroom is only a few years old, with tiled walls and floor, so there's no way that I can re-wire it.

yes there is a way. If you can't see it, pay me a thousand pounds and I will show you.