RCD Trip x1 test no reading

[geor1970]

I was called to an office in a field today (tt system)

The led lights and sockets (separate circuits ) still have power when switched off at the switches ( lights on dim and socket neon half bright)

I did a ze test at the board and had to replace the earth rod.

The reading at the board is now okay but when i plug in my kewtech meter to do the zs the RCD trips

It also tripped on x1 trip test but failed to give a reading (it said NIL)

They have had loads of different unqualified electricians working in there and its a busy office where do I start?

 

[Dave OCD]

Have you checked the polarity ?

 

[Clive P]

Hi,

A couple of questions first-

What was the reading on the rod, and what is it now?
What size and type of RCD are you testing?
What setting are you using on your meter?

Regards.

 

[davesparks]

What was causing the original fault?

 

[geor1970]

Sorry I didnt explain very well I havent found the fault I need to back after working hours the fault is still there i just noticed the missing earth rod and renewed it .
The Rod was disconnected before but the new reading is now 23ohms
The Rcd is 63a / 30ma standard MK board.
Problem A. the power still going to sockets and led downlighters when switched off
Problem B. The Zs from socket trips rcd
problem c. The rcd test trips at x1 but no reading ?

Im using kewtech kt60 comi tester (anti trip)

I havent checked the polarity maybe a start?

Regards.

 

[davesparks]

Find the damn fault!

There's no earthly point trying to carry out those kind of tests with what could potentially be a very serious fault in the installation!
Get the fault found and repaired before someone gets hurt!

 

[geor1970]

I was just called out to look at the lights but earthed the csu before leaving Im not sure where to start first on the rest.

 

[davesparks]

If you don't know what you are doing then employ an electrician who does

 

[geor1970]

Thanks for your help

 

[Hellmooth]

The sockets are still on when the switches are off? Do you mean the mcb?

 

[geor1970]

There is a power supply for cctv with LED lights plugged into a ring main when you switch the plug off at the socket the lights stay on dim but on as do the ceiling lights ( different circuit) There must be a wiring fault somewhere but its a busy office and apart from doing a full test and closing them down i cant think where to start I first thought an earth fault L/E and found the missing earth rod but the rcd still trips when i do x1 test reads nil and when i try the zs at the sockets it trips

 

[Hellmooth]

I'm sorry you've lost me........

When you go back you need to start testing as you would any other installation, then give a bit more detail when you have results.

 

[geor1970]

basically there is still a weak current still passing through sockets and lights when switched off at the light switch... lights are staying on dim and neons in sockets still lighting up when plugged in but switched off at the sockets I will have to do a full test but its hard as its a office open 24hrs and will need to shut down and they dont seem to understand the seriousness of the situation thanks for your help ill investigate more tomorrow

 

[davesparks]

What exactly do you mean by a full test? What will you test and why?

 

[Hellmooth]

Do you have a leakage meter? Worth trying to see what current is being drawn, strange one though if it's turned off!

 

[davesparks]

Do you have a leakage meter? Worth trying to see what current is being drawn, strange one though if it's turned off!

To what end? The flow of current is an effect rather than a cause.

Better to consider what is causing the current to flow.

 

[Hellmooth]

Post has puzzled me tbh!

i was thinking about plugging in a stripped down extension lead (insulation stripped so to expose inner cores) and seeing what current was being drawn on conductors, probably not get the OP very far though in hindsight, would need to be there myself!

I'm off to bed before I think of any other useless info to pass on......

 

[davesparks]

basically there is still a weak current still passing through sockets and lights when switched off at the light switch... lights are staying on dim and neons in sockets still lighting up when plugged in but switched off at the sockets I will have to do a full test but its hard as its a office open 24hrs and will need to shut down and they dont seem to understand the seriousness of the situation thanks for your help ill investigate more tomorrow

What do you need to shut down?
What testing are you going to carry out?

You have current flowing when it shouldn't be. What causes current to flow?

 

[NDG Elecs]

LED lamps can emit a very dull glow even when isolated. I have two examples of this in my house. First is a GU10 spot. This occurs on only one of four identical lamps, it cannot be an earth fault as there is no CPC connected. The second is a exterior LED spotlight, although this is earthed the glow can remain for a while after the DP FCU is switched off.

Never found out the cause of this. Mr Nunes or Mr Burns please? Or anyone else !!!

As for the neons glowing I do not know either. But further investigation is needed. You, or your employer, need to emphasise to the person that requested the work, that further testing is required. Try bypassing the RCD to do your Zs test. Try testing the RCD by itself and in isolation rather than from a socket. My MFT can go a bit haywire if the batteries are weak, so maybe new batteries are required.

When you come across a puzzling fault it can be easy to lose track of things. Get a pen and a pad at the ready and test the installation methodically. Good luck fella.

 

[Midwest]

That's more constructive.