Rcd advice needed faulty or fault

[Stuportsmouth]

So had to fit a new shower as old one kept tripping the rcd after few seconds assumed the shower was to fault as made a buzzing noise and tripped, on fitting the new shower it had same faukt so checked pressure of water no issue then checked wiring at box also no issue so moved onto next possibiliy of short on cable.
Yes maybe should of used multimeter and tested each one out but easier as short run in walls so run new cable exactly the same.
So decided to wire a small flex with bulb holder on that trips rcd changed the 40amp mcb to a 16 amp tried light also trips could this be a faulty rcd its rated 80amp 30ma, we also tested the the curcuit with every mcb turned off with only shower circuit on and also tripped.

Any help would be greatly appreciated as would like to think in a 6 bedroom house with each room occupied that of rcd was faulty then it would trip as currently has approx 8 circuits on and only randomly started to happen nothing new has been added.

 

[Deleted member 105166]

Have you done a ramp test on the RCD?

 

[Pete999]

Not an Electrician then? about time you got one in to test the system properly with the correct test equipment, "lamp and a bulb holder oh dear me DIY disaster on the horizon if I'm not mistaken, do yourself and whoever is helping you a big favour, leave it well alone and get a Sparky in to sort it for you, before you do yourself and your Mate some mischief.

 

[Deleted member 105166]

As an aside, is circuit #3 no longer "spare" ?

 

[Stuportsmouth]

Been doing electrics since the age of 10 mate dads fully qualified also worked doing electrics for both single phase and 3 phase air conditioning installs he is 18th edition certified and have been trained to the qualified standard of him.
I also run all the electrics in the house when was converted in the property it located in and as you can see was fully inspected and checked by a fully qualified electrician and signed off as you can see in the picture of the fusebox I am more than capable of checking things out.
Also I have checked all earths neutrals and lives on the mcb

 

[Pete999]

Been doing electrics since the age of 10 mate dads fully qualified also worked doing electrics for both single phase and 3 phase air conditioning installs he is 18th edition certified and have been trained to the qualified standard of him.
I also run all the electrics in the house when was converted in the property it located in and as you can see was fully inspected and checked by a fully qualified electrician and signed off as you can see in the picture of the fusebox I am more than capable of checking things out.
Also I have checked all earths neutrals and lives on the mcb

The 18th edition of BS7871 aint out yet?

 

[Stuportsmouth]

Have you done a ramp test on the RCD?

Circuit 3 is spare it was originally installed for a circuit that's didn' and up being installed and am going to get a blank for that tomo and remove

 

[Pete999]

Been doing electrics since the age of 10 mate dads fully qualified also worked doing electrics for both single phase and 3 phase air conditioning installs he is 18th edition certified and have been trained to the qualified standard of him.
I also run all the electrics in the house when was converted in the property it located in and as you can see was fully inspected and checked by a fully qualified electrician and signed off as you can see in the picture of the fusebox I am more than capable of checking things out.
Also I have checked all earths neutrals and lives on the mcb

Checked? what with?

 

[Deleted member 105166]

...he is 18th edition certified and have been trained to the qualified standard of him.

The 18th edition isn't published until next year.

 

[Deleted member 105166]

Circuit 3 is spare it was originally installed for a circuit that's didn' and up being installed and am going to get a blank for that tomo and remove

The spare MCB is fine, it was just confusing to see it on, whilst the spare on circuit #1 is off... hence the question as to whether it was really "spare" or the labelling not updated.

 

[Stuportsmouth]

The 18th edition of BS7871 aint out yet?

And it maybe 17th he had as when working with him many years ago it was 16th haven' done a huge amount of electrics in last 15 years however have done bits a pieces in that time if it' not going to be a simple fix then I'll call my mate out to have a look but just can' get my head around why it trips when it's a 1 cuircut feed to shower of around 8 feet and with every mcb switched off it still trips rcd and on a 16amp breaker still trips the rcd with a 1 bulb light fitted

 

[Stuportsmouth]

Checked? what with?

When house was rewired he checked every plug socket unscrewing checked all wiring and earthing and measured each individual with his testing equipment and also pat tested all appliances on house he is full nic eic certified

 

[Stuportsmouth]

When house was rewired he checked every plug socket unscrewing checked all wiring and earthing and measured each individual with his testing equipment and also pat tested all appliances on house he is full nic eic certified

Also forgot to mention I also tried the shower on the unprotected rcd side still tripping the rcd out

 

[Pete999]

Also forgot to mention I also tried the shower on the unprotected rcd side still tripping the rcd out

Did you connect the N to the N busbar that corresponds with the non RCD side?

 

[Stuportsmouth]

Did you connect the N to the N busbar that corresponds with the non RCD side?

Originally no but was done today and still caused the same issue like I said it was all originally working fine without anything being changed over and the old shower unit has also been tested and works fine

 

[Octopus]

Where is the circuit for the shower? What rating is the MCB?

Strikes me that without proper test kit and the knowledge to use it and interpret the results you may well be wasting your time ....

 

[Stuportsmouth]

Where is the circuit for the shower? What rating is the MCB?

Strikes me that without proper test kit and the knowledge to use it and interpret the results you may well be wasting your time ....

40amp mcb and mcb is also not tripping used the spare 16amp with lightbulb circuit and still done same a ramp test could be beneficial to test the rcd but then changing the rcd of possibly faulty is also easy main thing being tho of the rcd is faulty it would trip with all the other circuits on board under load and would assume with then isolated that if there was a fault on a circuit with all mcbs turned off that would isolate any fault.
Shower is currently not on any circuit as removed from box and left isolated outside of fuse box

 

[Octopus]

40amp mcb and mcb is also not tripping used the spare 16amp with lightbulb circuit and still done same a ramp test could be beneficial to test the rcd but then changing the rcd of possibly faulty is also easy main thing being tho of the rcd is faulty it would trip with all the other circuits on board under load and would assume with then isolated that if there was a fault on a circuit with all mcbs turned off that would isolate any fault

Punctuation would help!

using what?

regarding isolation of circuits using MCB's, best you ask your dad about how RCD's work ....

 

[123]

What concerns me here is everything is going to be tried until the shower works and nothing trips...and then its going to be left at that as it works

 

[AJshep]

With the greatest respect Stu. I'm with the others I think it's best to get someone qualified to look at this.
It's going to involve disconnecting and testing circuits, and I personally wouldn't want to advise someone over a forum especially when it could cause serious injury or death.