Electric Shower help please

[RUGBYMAN904]

hello all new to this brilliant site.

About a year ago my daughter and her friend flooded the upstairs bathroom...bless em ...lol
Directly below is the downstairs bathroom. Im not sure if related but I started smelling burning/ fishy smell and the electric shower a triton opal 2 fused from the pull switch. I replaced the pull switch which was badly burned and damaged inside also lots of burned cables, everything worked brilliant for 6 months and now again the the shower is fusing (no burning)the whole house. I have replaced pull cord again this time still fusing.

I have isolated the shower .....

examined the shower no obvious damage....

thanks

 

[ricicle]

Can you just clarify your meaning of the term 'fusing' ?

 

[RUGBYMAN904]

Tripping out the whole houses electrics

 

[riveralt]

Tripping out the whole houses electrics

The normal process for identifying RCD problems is to try and isolate the cause of the trip - in this case you appear to have done this.

The next stage would be to identify and examine the points of potential high resistance - again you have done this either by replacing damaged parts or inspection -was the damage across both conductors or just the neutral?

From your comments I will assume that you correctly connected the conductors in their right terminals at each stage of the process from the Consumer Unit MCB to the ceiling mounted isolator and the shower itself.

Do you have a multi meter?

If so then the next stage would be to carry out continuity and insulation resistance tests on the circuit itself while dead.
That involves isolating the circuit removing the conductors from the MCB in the CU - (DO not do this unless you are comfortable working inside the CU - remember even when the main power switch is off parts of the CU will still be live.) and the shower itself.
Since it is unlikely that you have a multi meter with the facility to test insulation resistance you may be restricted to testing continuity for each of the three conductors.
At one end of the circuit join the Live and earth and then test between live and earth at the other end. Do the same for Live and Neutral.
You should expect a low Ω reading - depending on the length of the circuit and the cable size nothing much more than 0.5 Ω. High reading would indicate you have problem with either a damaged conductor or a loose or damaged termination somewhere along that particular cable.

You could also test live but I would not suggest you do that unless you are very confident you know what you are doing.

If everything checks out then the problem may be the shower itself in which case you may want to get someone in.

 

[RUGBYMAN904]

Thanks for that ill buy a multi meter and have a go but excuse me a bit confused re the terms CU? consumer unit is that the box under the stairs with all the fuses? and the MCB? so sorry perhaps I should know these terms but a keen novice learning how to do some basics. Thanks

 

[riveralt]

Thanks for that ill buy a multi meter and have a go but excuse me a bit confused re the terms CU? consumer unit is that the box under the stairs with all the fuses? and the MCB? so sorry perhaps I should know these terms but a keen novice learning how to do some basics. Thanks

Slightly concerned that you don't know the type of CU (Consumer Unit) type you have. Particularly as there are many types and many different arrangements of each type.
If you can a photograph of the CU and surrounding wires that would be helpful to try and identify what you are dealing with.

For example you have semi-wireable fuses - when the fuse goes you have to replace it with fuse wire.
Minature Circuit Breakers (MCB) these are 'fuses' that can be reset by flicking the on/off switch.
RCCB & RCD (residual circuit breakers) that can also form part of the main switch they would normally have a flick on/off switch and a push button with the word 'test' on it.

The RCD can be integrated into the CU in a number of ways.

RCBO which combine the MCB and RCD together.

On top of that each breaker/fuse will have a different rating pertinent to the circuit it is protecting.

Remember that electricity takes no enemies - it can and will kill you if you don't treat it with respect.

So unless you are 100% certain you know what type you have and are able to totally isolate the CU before opening it I would not touch it and call someone in.

 

[RUGBYMAN904]

Thanks its mcb the mini circuit breakers the shower one is a MERLIN GERIN C60HB 63 AMP TYPE B 10KA 240V SINGLE POLE MCB CIRCUIT BREAKER 25850.... . I will thouroughly research before I try anything and appreciate the help . Can anyone recommend decent inexpensive multimeter.

 

[Iggifer]

well you have, arguably the best make of MCB (and hopefully consumer unit)

I would be expecting the fault to be with the shower itself rather than the cabling. That's not to say there is no cable fault, there may be.

 

[EFLImpudence]

It's not that one that's tripping - I hope - is it?

As said above, it is presumably an RCD which is tripping because it takes out the whole house, although you could have a whole house on that mcb.

Can we have similar details for the actual one that trips, please.

 

[sparkiemike]

Thanks its mcb the mini circuit breakers the shower one is a MERLIN GERIN C60HB 63 AMP TYPE B 10KA 240V SINGLE POLE MCB CIRCUIT BREAKER 25850.... . I will thouroughly research before I try anything and appreciate the help . Can anyone recommend decent inexpensive multimeter.

It's not that kind of multimeter, more like this
http://isswww.co.uk/17th-Edition-Testers

 

[Aragorn84]

63A sounds high for a shower?

 

[ban-all-sheds]

It does indeed. A bit high for the likely cable too.

 

[riveralt]

Thanks its mcb the mini circuit breakers the shower one is a MERLIN GERIN C60HB 63 AMP TYPE B 10KA 240V SINGLE POLE MCB CIRCUIT BREAKER 25850.

Like others have pointed out this is the wrong size MCB for the shower you have.
The manufacturer instructions indicate that a 40Amp MCB is required for this shower protecting a minimum size of 6mm² T&E cable.

For example:
http://www.amazon.co.uk/electronics/dp/B005ZPLZOK

The purpose of the MCB is to protect the cable from overload conditions - so that the MCB will trip before the cable burns out.

 

[Aragorn84]

theres a 10.5KW version of that shower and it requires 45A MCB and 10mm cable going by the MI's.

Really needs to be specced for what he actually has.

 

[securespark]

I know the regs about following manufacturer's instructions. However, a shower is a fixed load.

As long as the MCB has been correctly selected to suit the cable CSA taking into account the installation correction factors, then I can't see a major problem.