Lighting circuit trips out RCD

[pinkaroo]

Hi, I have a problem with the lighting circuit in my house. Firstly it is an overhead supply and, in order to build an extension I had to remove the earth rod from the ground and I have yet to replace it. The power to all MCBs is supplied through an RCD. Yesterday whilst moving an armoured cable the RCD tripped and would not reset. I turned all the MCBs off and the RCD would still not reset. I then removed the red and black cables from the lighting circuit as this cable was the one I disturbed when I moved the armoured cable. I was then able to reset the RCD and power came back to all other circuits. When I reconnected the red cable to the lighting MCB nothing tripped but when I touched the black cable on the neutral bar connection the RCD tripped and would not reset. About three weeks ago I had to replace the RCD unit itself after a thunderstorm. I disconnected the three leads from the lighting MCB to a spare MCB and when I connected the red cable the RCD tripped out again. I fear I have damage to some cable in the lighting cable but how do I find it if perceived wisdom decides this is the problem. Is there a meter I can buy which will help me test sections of this circuit ? I have a reasonable amount of knowledge and can work safely. Help.

 

[Adam_151]

I had to remove the earth rod from the ground and I have yet to replace it.

I have a reasonable amount of knowledge and can work safely

 

[Qedelec]

I concur with your post Adam.
Pinkaroo, without wishing to insult you, from your comments I would strongly suggest contacting a 'Qualified' Electrician at once, The earth spike is for your protection and should not be disconnected whatever the reason.

 

[ban-all-sheds]

I had to remove the earth rod from the ground and I have yet to replace it.

I have a reasonable amount of knowledge and can work safely

I am very ignorant and a serious danger to myself and all those around me.

 

[Igorian]

 

[pinkaroo]

Thanks guys, now any chance of a hand?

 

[Big_Spark]

Pinkaroo, you obviously know less than you think you do, and it would seem, from your post, that you have created a Neutral - Earth Fault on your lighting circuit.

The fact that you don't have a clue what the issue is, also tells me that you do not have the experience and knowledge to fault find the circuit and thus effect a safe and satisfactory repair to this circuit, as such I would seriously suggest that you contact an Electrician and get them to do this for you.

Also, You should refit the Earth rod urgently, without this you and your family are at serious risk of a fatal shock with limited protection.

 

[plugwash]

and if you actually pulled the earth rod out rather than simply disconnecting it you should probablly have a new rod hammered into fresh earth and tested with the proper equipment.

 

[ban-all-sheds]

and if you actually pulled the earth rod out rather than simply disconnecting it you should probablly have a new rod hammered into fresh earth and tested with the proper equipment.

Which he did:

I had to remove the earth rod from the ground

Another question - pinkaroo - presumably as there is building work going on, Building Control are involved in the work for this extension - what are you/they doing regarding the electrical aspects, and compliance with Part P?

 

[pinkaroo]

Guys, Thanks for your help. I have reinstalled the rod back in it's original hole and reattached the cable. I am big enough and ugly enough to take your criticism on the chin with good grace. My understanding is that I should firstly look at the individual light fittings on the circuit one by one to check for faults. I found some soot on an earth lead in a choc block and have removed that light fitting and it's lead and switch lead and reconnected the lighting circuit but this did not cure the problem. I then tried to reconnect the MCB but nothing had improved. I guess I must now remove each light fitting from the circuit individually and reconnect the MCB to rule out these light fittings and then turn my attention to the cable leg by leg. Is this about right? By the way an electrician is coming tomorrow,yes Sunday, to take a look see. Thanks.

 

[securespark]

Get him to check also that your rod (the earth one.....) is working as it should, as you have reinserted it into the hole and it may no longer be effective.

 

[pinkaroo]

Success. Mr Spark found by testing that when red of lighting circuit was connected to spare MCB the RCD tripped out so went alooking around the circuit. Removing one of two dimmer switches revealed the live in the switch had been pressing against one of the redundant lugs in the wall box and had burned out killing the switch. The other dimmer switch on the same two way switch had also stopped working. So a lesson learned on fitting switches. The earth rod was tested and found to be within limits.

 

[ban-all-sheds]

When were the dimmer switches fitted? You didn't mention them in your first post, as being recent work on the lighting circuit.

 

[pinkaroo]

Those dimmers have been fitted and untouched for 3 years and had not given any trouble. Thanks for your replies so far guys.