Shower Failure

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Good afternoon all. Just discovered this forum half an hour ago.
I have an interesting (well I think it’s interesting) problem.

Electric shower with ceiling switch; fed from its own ELCB at the consumer unit.
Turn on the ceiling switch. Wee light on the switch comes on OK. There's live to the inside of the shower. But the power light on the shower does not come on.
Press the shower button. Nothing happens. Wee light on the ceiling switch goes OUT. There's STILL live to the inside of the shower.
I've not come across anything quite like this before.

After much background brain work I'm guessing a fault in the neutral side of the switch or maybe the ELCB.
Views? Which is most likely?

PJ
 
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How do you know its live ... exactly how did you test. If you used a neon screwdriver ... bin it.
 
Panjandrum said:
BO,
Your comment is not terribly helpful.
PJ
I asked a simple question. How did you determine that there was live at the shower?

Now why did I ask this?

Let me explain.

If you detected it with a neon probe they false report.

If you measured it using a meter to neutral then there must be some circuit back in the neutral or it’s joined/shorted to earth downstream.

If you measured it to earth it tells us nothing of the neutral’s condition.

You also didn’t say if the ELCB trips.

By ELCB do you mean an RCD or a vELCB?. Either way if its labelled ELCB is probably well past its best. What size and rating were the shower, how old, fuse rating etc?

I would also not recommend to anyone to test on live electrics unless you are sure your test equipment and skills are up to the job. It only takes on slip and we will never hear from you again.
 
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Slightly more helpful :D
Neon - yes. False positive reporting I have not come across.
CB dark cupboard so not absolutely sure of variety, but it does not trip and tests OK.
Shower 2.5years old and appears to be in fine condition with no scorch or overheating evident internally or at any connections.

Still looking for views wrt my speculation on likely cause; and if I'm right the relatively likelihood of CB or switch.

PJ
 
Panjandrum said:
Neon - yes. False positive reporting I have not come across.

they are not reliable. i even had one of mine light up at under 20V, so when you say live, you do not know the voltage. use a multimeter and test between phase and neutral and see what voltage you get
 
OK, so there are reservations about the capability of a neon mains tester.
It has been pretty reliable for me, clear of any significant radiation source.
However, point made, and I will file that as a useful piece of information for future reference.
But I was kind of hoping that someone here might care to offer an opinion on the fault, not on the test device.
Lack of detail on the CB is down to it living in a dark cupboard not in my own house - quick inspection last night without torch.

PJ
 
we need to know the facts first, which you ARE NOT providing
 
OK then.
Ignore previous posts.
FACT - main shower ceiling switch indicator light operates exactly as you would expect. It lights up when you pull the switch on. It goes out when you pull the switch off.
FACT - the light on the switch stays on until you try turning the shower on. At that point it goes out.
FACT - using a neon tester, admittedly something that seems to be unaceptable on this forum, there is some evidence of continuity through to the shower when the ceiling switch is on, even when the light goes off.
FACT - the power light on the shower does not come on, ever.
OBSERVATION - as an experienced DIYer of many years standing with profound sense of self-preservation and appreciation of when it is important to stop because of experience deficit, this is an unusual situation.
OBSERVATION - this seems to me likely to be a switch fault or a CB fault.

QUESTION - in the opinion of readers, does this make sense and which is most likely?
It seemed to me to be an honest request. I am a little surprised at the reaction.
PJ
 
the reaction is because you used a "tester" they are known to be unreliable.

i think the neon is either a give away or a red herring, but without being there i can not say for sure.

But i do think this:

neon (in switch) is lighting because it is "backfeeding" through the shower, when you turn the shower on you are putting a load (the shower itself) across L + N
this load redues the current / voltage to bleow that the the neon will work at.

i would be inclined to check the neutral connections, but obviously switch off at the consumers unit first
 
i presume where you said elcb you meant rcd (technically an elcb is something different that isn't used any more but a lot of people use the term to refer to rcds

live on a neon tester tells you there is some voltage there relative to the potential your body is at but they don't tell you how much. Also i thin
k thier have been some accidents invlolving the things (i hear an apprentice dropped one in the cold water tank and just wiped it off and then his boss used it to use a cuircuit BANG)

if you are going to find this problem then first you need to get yourself a multimeter (even one of the really cheap ones will do fine here)

then you need to turn the shower on (so the light goes out) and carefully measure for voltage between live and neutral at each point in the cuircuit (input to rcd output from rcd input to isolator and output from isolator)

take great care not to touch live parts when measuring especially at the isolator

if the fault is in the rcd or isolator then its easy enough to replace it

if the fault is in the cable then its probablly best to replace the whole run as trying to find where in the cable the break is is goign to be extrememly difficult
 
Much thanks guys. My faith is restored.
I will test, with great care, where there is continuity, hopefully replace the appropriate part, and report back. I do expect to live that long.
This problem is in another location, not my own house.
Slack terminology relating to the CU is down to my looking at to my own CU, which does have ELCBs and was installed (part-time by local supplier inspectors) in 1987, just weeks after I moved in.
That replaced 1920s wiring which included reversal of live/neutral between front and back of house and a central heating system connected to the lighting circuit. I knew when the pump came on because the lights dimmed.
 
Carefully using primitive test equipment I confirmed the switch was faulty.
Now replaced and all well.
The old switch shows signs of overheating inside the loadside N terminal.
PJ
 
if only you had a multimeter in the first place, it wouldnt take 5 mins to find the fault
 
Totally agree. Unfortunately my collectively-owned meter is with the other half of the collective at the moment so the diagnosis was a touch uncertain until confirmed tonight.
PJ
 

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