Zs reading with main earth disconnected

[7029 dave]

If you have main earth disconnected , surely it would be ZE not ZS.? (at source)

 

[DPG]

If you have main earth disconnected , surely it would be ZE not ZS.? (at source)

He says he's checking a lighting circuit though, not at the source.

 

[dtec dave]

Parallel path via CPC to boiler circuit CPC to boiler manifold to pipework within the fabric of the building?

Also why is the installation energised with the main earth disconnected?

 

[dtec dave]

So to answer why I had the circuit energised with the main earthing disconnected..

The lighting circuit connected in board had no CPC so I checked the Zs at a ceiling rose.

I had a reading of 2.2 ohms so I then tried to find out where the earth was coming from.

I disconnected all the CPC's from the other circuit in the board, checked Zs again and still had 2.2 ohms.

Just try and eliminate things and to see if I was picking up earth from elsewhere I then disconnected the main earth and still had a reading of 2.2 ohms.

 

[dtec dave]

Parallel path via CPC to boiler circuit CPC to boiler manifold to pipework within the fabric of the building?

Also why is the installation energised with the main earth disconnected?
[/QUOTE

 

[Charlie_]

Many years ago I used to disconnect the main earth and carry out various tests to help me understand parallel earths in electrical installations.
Done lots of other experimental testing in a controlled environment...

 

[westward10]

Disconnecting the earthing conductor for an energised system isn't the wisest thing to do. You are better to try dead tests by way of a continuity tester.

 

[buzzlightyear]

Many years ago I used to disconnect the main earth and carry out various tests to help me understand parallel earths in electrical installations.
Done lots of other experimental testing in a controlled environment...

working on the HIGGS BOSON PROJECT.

 

[Baddegg]

Many years ago I used to disconnect the main earth and carry out various tests to help me understand parallel earths in electrical installations.
Done lots of other experimental testing in a controlled environment...

You can’t make an omelette without breaking a few eggs.....

 

[davesparks]

Just try and eliminate things and to see if I was picking up earth from elsewhere I then disconnected the main earth and still had a reading of 2.2 ohms.

Why do this as a live test when that means doing something as stupid as energising the installation with the earthing conductor disconnected?

Electricians are supposed to understand the fundamental principles of electrical safety!