# Struggling to find fault.



## Coalman (Nov 26, 2013)

Looking some help.

I have a small fuse board (3 way),sockets blowing fuse and rcd.
Replaced and found no faults anywhere.
2 weeks later rcd going off.Removed rcd to help find fault.No fault found and all powered up perfectly.
2 Weeks later fuse blows.Replace fuse with mcb and find the mcb going off right away.
When power up the 2x2.5mm cables buzz with a noise.There is no load on the circuit.
Connected to a new PME Earthing System.Disconnected the Fuse Board and 16mm cables supplying Fuse Board.
Now,hard to beleive,the 2x2.5mm cables,starting and stopping,start to buzz,with no cables connected to the electric boards meter.There is a 2nd small fuse board supplying lighting.Does the earthing system have a fault.
Reconnected earth cables at the main earthing connector and got a shock from a earth cable.When measuring volts between earth cable found readings from 120v 227v.Spend a day trying to solve this problem,given up for the day.
Who can help?


----------



## HARRY304E (Sep 15, 2010)

Coalman said:


> Looking some help.
> 
> I have a small fuse board (3 way),sockets blowing fuse and rcd.
> Replaced and found no faults anywhere.
> ...


Hello welcome to the forum.:thumbsup:

You will get more help if you post on this forum.

http://www.electriciansforums.co.uk/forum.php

Good luck


----------



## Zog (Apr 15, 2009)

Explain what you mean when you say "No fault found"


----------



## Coalman (Nov 26, 2013)

I'am unable to find any reason why the fuses are blowing,or the rcd tripping.
Even when the mains cables supplying the fuse board are disconnected from the main 240v terminals something causes the 2x2.5mm cables to buzz.This buzzing starts and stops.Disconnected all earthing conductors at the main earthing terminal,believing a fault in an earth path somewhere?? and got a live shock between two earth cables.Measured different voltages between earth cables.


----------



## Coalman (Nov 26, 2013)

Connected all earth cables back into main earth terminal.Any test which we wish to carryout highlights reversed polarity.Put everything back together and everything worked ok.2 hrs later rcd starts tripping again and then fuse blows.


----------



## gnuuser (Jan 13, 2013)

Coalman said:


> I'am unable to find any reason why the fuses are blowing,or the rcd tripping.
> Even when the mains cables supplying the fuse board are disconnected from the main 240v terminals something causes the 2x2.5mm cables to buzz.This buzzing starts and stops.Disconnected all earthing conductors at the main earthing terminal,believing a fault in an earth path somewhere?? and got a live shock between two earth cables.Measured different voltages between earth cables.


the fault may not be in the panel but in the earth cables
this sounds like a neutral short in a junction box (short between neutral and ground/earth)
(found this once in a residence while installing new ground/earth cable! in the main panel.
neutral short was in a ceiling light on the third floor)


----------



## Zog (Apr 15, 2009)

Coalman said:


> I'am unable to find any reason why the fuses are blowing,or the rcd tripping.
> Even when the mains cables supplying the fuse board are disconnected from the main 240v terminals something causes the 2x2.5mm cables to buzz.This buzzing starts and stops.Disconnected all earthing conductors at the main earthing terminal,believing a fault in an earth path somewhere?? and got a live shock between two earth cables.Measured different voltages between earth cables.


What tests have you performed? (Swapping out parts is not testing)

Have you tested the insulation of the cable?


----------



## JohnR (Apr 12, 2010)

It "sounds like" you have a neutral problem. Like a broken neutral at the transformer. 

But, I understand you to say that you have all loads disconnected from the main panel, just the meter and main feeds connected?? And the loomex, romex, 2.25mm, load circuits are buzzing with no power apparently connected? 

I this is the case, it could be that you have power lines nearby? and they have a bad ground or bond.


----------



## beardie (Sep 12, 2013)

Sounds like insulation breaking down between either phase to neutral or phase to earth 
You need to Megger sub circuits with everything off eg bulbs out
Visual signs moisture carbon tracking water cylinder elements mice radio suppressors in fluos


----------



## boora2 (Jan 28, 2012)

An intermittent leak to ground from scale buildup or a cracked element in a hot water tank has been known to cause this,as a quick bodge,bypass the thermostat for a FEW minuites,then operate the T and P valve,might blast the crap out of it


----------



## gnuuser (Jan 13, 2013)

these fellows are correct you need to megger the circuits to find the faulty one 
this will give you a better picture of whats going on
going by guesswork is not an option in our trade


----------



## WarrenG (Apr 25, 2012)

Coalman said:


> Looking some help.
> 
> I have a small fuse board (3 way),sockets blowing fuse and rcd.
> Replaced and found no faults anywhere.
> ...


If you have disconnected the small 3 way board (inc Tails) from the incomer and still getting power through it, then you must have an interconnection between this board and the other lighting board.

To add to this there is obviously a fault. 

I can't see the install but it sounds to me that there is a direct short finding the path of the socket circuits. Check for light fittings that has been spurred of the sockets and then interconnected with the other lights fed from the second board?

Check your neutrals are where they should be i.e that a neutral return hasn't been used as a switch wire. Common neutral and neutral fault back tracking?

You would really need to check thoroughly the circuits for seperation and polarity baring in mind the switching arrangements for the lighting.


----------

