Shower tripping RCD

[NozSpark]

Sorry mate, but I need to know a little more about you and your electrical background because not much of this is making any sense.

 

[Pompeyblue]

I'm a newly qualified registered sparky. Under Napit.

My background is mainly IT/AV, but qualified last year as a sparky. so always encountering new electrical problems along the way. Which of course it excellent for gaining some experience, but I only take on what i know. (and this being my own shower is great to work with) Wiring faults and installations i'm perfectly fine with, but parts inside showers are new to me.

So unfortunately i'm researching, researching researching.

 

[Doc Hudson]

Yeah. I tested those first.Someone mentioned that the fault could be caused on the neutral somewhere else in the house....So i removed all circuits from the CU and still the rcd tripped.

I really appreciate any help you could through my way Noz.

Where were you testing between, what meter type & ranges were used and what were your test results? This information would probably make things easier for others to help you. A fault could be cause by multitude of causes but a bit more detail is needed from your testing.

Doc H.

 

[batty]

You could test by testing the l/n -e at shower see what insulation resistance is if its going down disconnect wires until you find what part it is. Only test at 250 volts that way you won't damage anything not sure if this will work as I generally would rather replace showers than fix them as the way I see it even if you do replace a part another part will probably go wrong shortly after and manfacturers generally hike prices so its not econmical to repair them. I would think the only parts likely to go down to earth is either motor or element unlesss something is leaking making other parts wet.

 

[NozSpark]

Thanks for that reply it does help a bit..

I'm assuming that you have a full set of test equipment here...

You have to be really methodical with this, test it like you would a new installation,,, it'll be good experience and you'll know you have a safe installation at the end of it!

One thing that stuck out is that you said that with ALL the circuits disconnected that the RCD still trips,, did you mean that the MCBs were off and neutrals were disconnected?

 

[Pompeyblue]

Thanks doc. I don't articulate the issues very well do I?

Ok i disconnected the circuit from the isolator to the shower and tested for continuity. Found that there was a earth fault on the element when tested across the terminals.

I thought that the motor could have caused it, but triton said his would be very unlikely....

Anyway swapped the can over and still it trips.

I would have thought the motor or element are the most likely to cause an RCD trip..

---------- Post Auto-Merged at 22:27 ---------- Previous post was made at 22:22 ----------

Thanks Noz. Yeah the MCB's where off and and the neutrals where disconnected.

I'm using a kt65 for testing.

I tested all cabling up to the shower, like it was new. And it's all fine, but i did do an insulation test on the cabling without disconnecting the shower...What in the shower could that have damaged, baring in mind it was only at 250v....

Thanks

 

[Evans Electric]

Has this thing been working OK for some time or have you just connected it ?

If so , is the neutral in the right bar?

Did you disconnect so that you're not meggering through the neon in the isol. ?

When you say "Tested across" have you tested from element to earth ?

 

[NozSpark]

Let me get this straight,,, I know I'm repeating myself here but bear with me...

With the MCBs off and neutrals disconnected the RCD still trips?

If that is the case then the fault lies elsewhere!!

 

[Pompeyblue]

Hi Evans,

Yeah i tested the the element to earth, and double checked the neutral was in the right bar.

Everything was working fine. Just one morning the fianc

 

[NozSpark]

Cheers,

Then the fault is very likely going to be with the shower..

All you can do is disconnect various components within the shower and test them to the showers earth terminal.. Don't remove the shower from the wall or disconnect any pipework though!

 

[Doc Hudson]

Is this shower one with a PCB, circuit board, with some electronics on, or is it just the manual rotary dials and micro switches. That is could it be a track breaking down on a circuit card?

Doc H.

---------- Post Auto-Merged at 23:33 ---------- Previous post was made at 23:32 ----------

Has the RCD been tested that it is working ok, not over sensitive?

Doc H.

 

[kme]

Okay.

I`ve done a bit with a couple of these showers and, TBH, not much can fail. Doc, if its what I think it is, it has a pcb on a ribbon cable in the front; handling the temp. compensation & pump speed issues.

Unless theres water getting in ( which should be obvious), the PCB is highly unlikely to trip the RCD - I don`t recall it having an earth connection, other than through one of the securing screws!

"Can a microswitch trip an RCD"????? From someone who has "recently qualified"? I`m scared now.

IF you can use your meter correctly, try insulation testing (at 250v) to various component parts of the shower, with the spade terminals disconnected. When you find the leaky part, you`ve correctly fault-found

n.b. It is highly unlikely that 2 different parts of the shower have developed earth leaks at the same time. I`d suggest that you`ve mis-diagnosed a fault on the can, if the problem has persisted.

If this is indeed the case, I`d recommend paying someone to come and do the fault-find for you - watch & ask - it`ll be a good learning experience.

KME

KME

 

[Pompeyblue]

KME - thank you for the advice, i will go around and individually test each part at 250v. I didn't notice a PCB but will double check as it is all twist dials.

Should it not be obvious after these tests, i'm happy to get someone to test it. Always willing to learn.

Many thanks for everyones advice. Will keep you posted on the results.

Ta

 

[SPECIAL LOCATION]

Just been reading through this?

Bit confused as to what exactly has been tested.. or proved..

and in what order?

is this your beastie..

Electric Showers

https://ww2.tritonshowers.co.uk/webapp/wcs/stores/servlet/CategoryDisplay?storeId=10001&catalogId=10001&top=Y&categoryId=10051

Thought I read that you had proved a fault on the can.

then replaced it..

but then fault still there so not proved???????

If water is part of the earth bridge path..

then all testing MUST be done with the water in the system..

BUT I would also have cables physically removed from the shower terminals to proved no fault path back up the incoming 6 or 10mm..

Anyway...

Does the shower ALWAYS trip immediately on ALL settings?

e.g. A Typical electric shower has 3 operating settings...

(a) Cold - No heat elements in circuit..

(B) Heat#1 - One heat element in circuit..

© Heat#2 - Two heat elements in circuit..

so..

What happens if you run it on the COLD ONLY setting?

What happens on Heat#1

What happens on Heat#2

may help eliminate if it is a specific single component?

Have you actually opened up an proved 110% that the shower isolator switch is OK?

It is VERY common for the isolator switches to have screw terminals that are not tight..

thus joints heat up.. conductors get warm..

Insulation starts melting a bit....

Then possibly making contact with an earth (CPC) wire bunched in the back of the isolator switch?

So as the shower draws power.. cable heats up..

Earth path made..

then cools down again later and fault path then disappears!

{Above points assuming typical ceiling cord pull isolator switch..}

Cant see any actual resistive readings from any of your tests?

i.e. what is the ohms values from your continuity and insulation resistance tests?

Are you aware of the typical values you get if reading through a Neon indicator..

Is this RCD only connected to the shower?

or does it protect other circuits as well?

 

[Pompeyblue]

Hi Special.

Thank you for the in-depth response.

The

 

[Doc Hudson]

The plot thickens as they say. Looking at the second picture that Special Location linked with the main parts. If its not the can, my next gut feelings would be the inlet solenoid, bottom right or the motor and pump assembly top. Have you done any 240v Insulation tests as Batty suggested?

Doc H.

 

[Pompeyblue]

Hi Doc

I found this link which has numbered the parts.

Triton T80si Pumped | Triton | Shower Spares | Shower Doctor

I'm going to put 240v across the solenoid and motor today and post back the results.

Thank you.

 

[Doc Hudson]

I certainly wouldn't go purchasing any more spares until you have proved a bit more of the fault path that is tripping the RCD. I was just thinking of the components that are likely to have direct connections to L or N when you switch the power on, as you say it trips off almost instantaneously.

Doc H.

 

[Pompeyblue]

Testing complete.

Disconnected the neon power light and solenoid from the shower. Still tripped.

Disconnected the Motor, i got mains pressure and power!

Disconnected Neutral from the motor and it tripped so the fault was between Live and Earth on the motor. The motor is totally dead.!

Many thanks to everyone for there advice.

I have picked up quite a bit from this experience.

PB

 

[NozSpark]

Pompey,,

You really need to test this using a continuity and insulation testers,,, your methods of disconnecting bits and re energising is going to be very hit and miss, if not potentially dangerous