400V between L&N

[Ago4Ago]

EICR on a Factory. I came across a consumer unit in an outdoor shed feeding a double socket (with a 4 way trailing lead with neon, plugged in) and 2 lights. Trying to locate where this consumer unit was fed from I plugged in a socket tester (one with the three indicator lights & a shrill beep). This indicated that there was a problem with the earth. I then plugged in my Earth Fault Loop tester to see what the Zs was; No reading. I then plugged the socket tester back in & only the right hand indicator light lit up this time, referencing a reversed line & earth as apposed to all 3 with a flickering left hand one as before; I then knocked the isolator off at the consumer unit & removed the cover, to find 400V between Line & Neutral. 230v between L&E and N&E. My question is: Could, trying to take a Zs reading from the socket have disturbed something earlier in the system to create 400v across L&N ?? As I am only employed to inspect & test on the condition of the installation. I isolated the circuit & did not investigate further at this point.

 

[telectrix]

or has some numpty wired it across 2 phases?

 

[snowhead]

or has some numpty wired it across 2 phases?

Sure looks like it, and I think the "comprehensive" plug in tester is now toast.

And this is a worrying Question from someone who tests;

My question is: Could, trying to take a Zs reading from the socket have disturbed something earlier in the system to create 400v across L&N ??

As I am only employed to inspect & test on the condition of the installation. I isolated the circuit & did not investigate further at this point.

 

[Ago4Ago]

Surely it would have blown any thing that had been plugged into the trailing lead or at least the neon? It is just puzzling me because as much as I would have liked to; I just hadn't the time and wasn't being paid at this point to investigate further.

 

[londonlec]

They must be changing those lamps regulary :d

 

[snowhead]

Were the 2 lights working as well as the neon, and did your tester show any voltage reading?

 

[Ago4Ago]

The plug in tester is primarily used as an audible devise to listen when the circuit is disconnected but also gives an instant indication as to anything adrift. And no it isn't Toast

 

[Ago4Ago]

Were the 2 lights working as well as the neon, and did your tester show any voltage reading?

No the lights were not working.

 

[Ago4Ago]

My tester read in the region of 230v prior to trying to take a Zs

 

[keniff]

or has some numpty wired it across 2 phases?

Id say this was the case!

 

[Ago4Ago]

This particular job is the worst I have ever seen in 30 years. The outside shed Scenario is just part of a catalogue of examples of very dangerous practice. I was warned not to look too deep, by the owner. However I have a reputation to protect as he has an obligation to protect his employees. Therefore it is being tested and inspected to BS7671 full stop.

 

[moddeydhoo]

Diy diy diy
or still diy

 

[Ago4Ago]

Sure looks like it, and I think the "comprehensive" plug in tester is now toast.

And this is a worrying Question from someone who tests;

As the impedance of the phase-to-earth loop is measured by connecting a resistor (typically 10 Ohms) from the phase to the protective conductor. A fault current, usually something over 20 A, circulates in the fault loop, and the impedance of the loop is calculated within the instrument. I was just wondering if anyone had had any experience of this creating a problem that might explain the reason for the appearance of 400v between L&N. Not sure why the criticism on posing the question?

 

[snowhead]

As the impedance of the phase-to-earth loop is measured by connecting a resistor (typically 10 Ohms) from the phase to the protective conductor. A fault current, usually something over 20 A, circulates in the fault loop, and the impedance of the loop is calculated within the instrument. I was just wondering if anyone had had any experience of this creating a problem that might explain the reason for the appearance of 400v between L&N. Not sure why the criticism on posing the question?

There's no way using a tester in the manner it was designed can alter the characteristics of a circuit such that 400v appears where you'd normally get 230v.


And if you are finding more examples of dangerous practices and the owner has warned you not tolook too hard, it begs the question should the installation still be in use by anyone, other that a tester, untill found to be completely safe?

 

[Ago4Ago]

I agree totally, the factory is closed at the moment due to Christmas and there is only myself & a colleague in the premises. I don’t think I have any powers to enforce the closure of the factory until in a safe condition. I can only submit a report to the “responsible person” emphasising the fact.