Earthing sparking

[Buzz1980]

Hi there I wanted to ask a question regrading earthing. If the metal framework of a building is all connected together welded and earth cable through aswell. If I take one cable from the frame of the building to a floating point will this give the risk of a cable becoming live at some point. The cable is not part of a electrical circuit as the live cables are disconnected but just wondered if there was a potential of the earth cable of becoming live threw fault. Basically all it is, is a wire of copper coming off the frame of the building. Is this anything to be worried about. Please help thanks bongo/trig

 

[Marvo]

I'm afraid I didn't entirely follow your post but it sounds like you're considering disconnecting a bonding strap or wire which is kinda worrying. What does the 'earth sparking' refer to in the title of your post? Did you disconnect the earth and it was sparking?

I can give you some general advice;

Never ever disconnect any part of the earthing arrangement or its associated bonding when the installation is still live. In some installations large earth currents could be flowing which could kill you and anything connected to the section of earthing you disconnect is likely to rise to a dangerous touch voltage which could kill someone else as well.

The whole idea of earthing and bonding is to create a zone or area in which is everything is bonded together to hold it at the same potential and the entire zone is earthed to hold it at zero volts with respect to ground. If you disconnect one area of the equipotential zone then dangerous voltages can develope between items in the same vicinity leading to electric shock.

If you're trying to extend the equipotential zone then it must be done from the MET, not by running wires from the frame of the building.

Maybe you can explain further exactly what it is you're trying to achieve and how you're thinking about going about it or maybe attach a sketch to help clarify.

 

[Buzz1980]

I'm afraid I didn't entirely follow your post but it sounds like you're considering disconnecting a bonding strap or wire which is kinda worrying. What does the 'earth sparking' refer to in the title of your post? Did you disconnect the earth and it was sparking?

I can give you some general advice;

Never ever disconnect any part of the earthing arrangement or its associated bonding when the installation is still live. In some installations large earth currents could be flowing which could kill you and anything connected to the section of earthing you disconnect is likely to rise to a dangerous touch voltage which could kill someone else as well.

The whole idea of earthing and bonding is to create a zone or area in which is everything is bonded together to hold it at the same potential and the entire zone is earthed to hold it at zero volts with respect to ground. If you disconnect one area of the equipotential zone then dangerous voltages can develope between items in the same vicinity leading to electric shock.

If you're trying to extend the equipotential zone then it must be done from the MET, not by running wires from the frame of the building.

Maybe you can explain further exactly what it is you're trying to achieve and how you're thinking about going about it or maybe attach a sketch to help clarify.

Hi thanks for the reply what it is there was a generator installed at one point but the cables have now been disconnected from the generator as this was feeding a control panel in the building. So what has been done by my work colleagues is the live cables disconnected and just coiled up next to panel so not live. Also there is an earth coming from the panel which has been coiled up next to panel as well this was connected to the generator. But there is another earth connected to the frame of the building to supply an earth for the panel which has been coiled up but still connected to the frame would this give the potential of current flowing down this cable even though it is not part of a electrical circuit as such all it is now is a cable connected to the frame coiled up. Would I have to disconnect this?

 

[Marvo]

Picking up an earth for the panel from the frame of the building sounds less than ideal it should have been from the MET or on its own rod. If it's now redundant I'd consider removing the panel entirely along with the earth that was taken from the building and returning the installation back to the way it was before the generator was installed.

 

[Buzz1980]

Picking up an earth for the panel from the frame of the building sounds less than ideal it should have been from the MET or on its own rod. If it's now redundant I'd consider removing the panel entirely along with the earth that was taken from the building and returning the installation back to the way it was before the generator was installed.

Hi again yeah I understand that but would the earth that is still connected to the frame of the building cause any problem. Or could you just leave it still connects to the frame as no part of any electrical installation? Thanks trig

 

[mechelec]

The earth attached to the steel frame of the building has no more chance of becoming live than the frame of the building has it ? Remove if not required or leave alone.

 

[Had8Lives]

The earth attatched to the frame of the building could have been there as an Earth Bond. I'd check that there is an Earth bond elsewhere for the frame of the building. Provided there is a bond elsewhere, I'd say the wire you've mentioned is redundant and could be removed.