Voltage on earth ar cu when earth disconnected from earth bar and mcb on

[Jimbo8]

Hi everyone I'm after some advice I've just noticed that my earth had voltage on when I disconnected from earth bar in cu when mcb was on could any one shed a bit of light on this thanks it is on ring mains and light ccts 

 

[binky]

what sort of voltage?

 

[Jimbo8]

Any thing between  118v and 33v 

 

[Jimbo8]

what sort of voltage?

33v to 118v

 

[Rob.]

Firstly, it is extremely dangerous to be disconnecting a circuits CPC with it still energized.

Are you measuring with a digital multi meter by any chance?

 

[Geoff1946]

Probably just capacitive coupling from the live conductor.  Why? Are you experiencing RCD trips or something?

 

[Jimbo8]

Firstly, it is extremely dangerous to be disconnecting a circuits CPC with it still energized.

Are you measuring with a digital multi meter by any chance?

Hi pal I do realise it not the thing to do I am aware of the dangers but I was alone in the house and I was just seeing if anyone else had come around this thank you

Probably just capacitive coupling from the live conductor.  Why? Are you experiencing RCD trips or something?

No rcd trips.

 

[Rob.]

As said, most probably capacitive coupling. 

Even more likely if you're using a digital meter. 

Was there a reason you were doing this? Sheer curiosity or, finding a fault?

 

[Jimbo8]

As said, most probably capacitive coupling. 

Even more likely if you're using a digital meter. 

Was there a reason you were doing this? Sheer curiosity or, finding a fault?

Yes pal fluke tester also megger multimeter and metrel multimeter all it was I had put the earth in wrong terminal so was moving it over when I noticed a little spark on earth when they was disconnected from each other ie was a ring main but when there together it's no longer there just never come across this before has I've never disconnected earths while a cct has been energised  before 

 

[Rob.]

If you got an actual spark, this is suggesting a more sinister fault. 

A floating capacitive voltage, shouldn't have enough energy to produce a visible spark. 

All other circuit testing ok? 

TNCS earthing by any chance?

 

[Murdoch]

Voltages such as you describe are more likely to be "phantom" and are only "there" because the CPC isn't connected to the earth bar. As for the "spark" - may suggest earth leakage.

Best get a spark with an earth clamp meter to investigate, to put your mind at ease.

PS. As others have said its not a wise idea to disconnect the CPC when the circuit is live.

 

[Jimbo8]

Voltages such as you describe are more likely to be "phantom" and are only "there" because the CPC isn't connected to the earth bar. As for the "spark" - may suggest earth leakage.

Best get a spark with an earth clamp meter to investigate, to put your mind at ease.

PS. As others have said its not a wise idea to disconnect the CPC when the circuit is live.

I am a electrician a clamp meter would only tell me the loading 

If you got an actual spark, this is suggesting a more sinister fault. 

A floating capacitive voltage, shouldn't have enough energy to produce a visible spark. 

All other circuit testing ok? 

TNCS earthing by any chance?

I believe it is a tncs rob but u do not get a shock off the voltage that's being produced by the earth 

 

[Jimbo8]

Voltages such as you describe are more likely to be "phantom" and are only "there" because the CPC isn't connected to the earth bar. As for the "spark" - may suggest earth leakage.

Best get a spark with an earth clamp meter to investigate, to put your mind at ease.

PS. As others have said its not a wise idea to disconnect the CPC when the circuit is live.

Hi Murdoch just in twenty plus years of doing this and have never seen it before I wonder how many sparks have never noticed this with the earths I understand what ur both saying and not to disconnect earths while mcb is on but how would we ever know this is happening  if I never did do it 

 

[Sharpend]

You might want to invest in one of these? 

https://www.google.co.uk/search?

you can get as said induced/capacitive  voltage however these don’t usually produce a spark? I’d test the earth leakage then the  circuit fully individually as a start. 

 

[Risteard]

I think you need retraining about safe working practices.

An incredibly dangerous and stupid thing to have done.

 

[Jimbo8]

You might want to invest in one of these? 

https://www.google.co.uk/search?

you can get as said induced/capacitive  voltage however these don’t usually produce a spark? I’d test the earth leakage then the  circuit fully individually as a start. 

Hi there I tested circuit fully insallation  resistance  999 and continuity all ok earth loop 0.81 and rcd all ok 

I think you need retraining about safe working practices.

An incredibly dangerous and stupid thing to have done.

Thanks for ur advise mate but just to let you it would only be dangerous if someone else was in the house just to let you know I was alone 

 

[Murdoch]

I am a electrician a clamp meter would only tell me the loading 

If you read my post again it says earth clamp meter ............... maybe I should have written earth leakage clamp meter.......

If you do fault finding, they are an expensive but extremely useful item to have 

 

[Risteard]

Thanks for ur advise mate but just to let you it would only be dangerous if someone else was in the house just to let you know I was alone 

It's dangerous regardless. You put yourself in harm's way by doing it.

 

[Jimbo8]

It's dangerous regardless. You put yourself in harm's way by doing it.

Have u ever checked the earths dont have voltage on pal guess not so maybe ur leaving people at harm 

If you read my post again it says earth clamp meter ............... maybe I should have written earth leakage clamp meter.......

If you do fault finding, they are an expensive but extremely useful item to have 

Cheers murdoch I'm rewiring house now just never seen this before but like we all know we never disconnect earths when its powered up just a one off and couldn't believe what I was seeing really appreciate  you taking time to chat with me thankyou 

 

[Risteard]

Have u ever checked the earths dont have voltage on pal guess not so maybe ur leaving people at harm

How exactly is disconnecting them from the Earth bar a good test for anything? And voltage is a potential difference so can only ever be between more than one point.