3

I have a 240V+-10V 2 Wire Single Phase (UK) supply with TT earth bonding (earth rod).

The breakers are double pole.

The issue is with a lighting radial circuit.

This is a new electrical installation and the electricians are about to finish.

The lights that are connected to the circuit power up fine.

One light is not yet connected to the switched live.

With one CB on I probed (using a multimeter, I aware this might not be the best way to test) between Neutral and earth and there was 230 Volts. I probed at a fixture (neutral to earth) and again, 230 Volts

  • What is an acceptable voltage between Live/Line and Earth?
  • What is an acceptable voltage between Neutral and Earth?
  • Should there be voltage between live or neutral to earth?

Is voltage between neutral and earth normal or could there be a fault?

This video states that there should be 0-0.5V between earth and neutral

This post on Quora states that

A rule-of-thumb used by many in the industry is that Neutral to ground voltage of 2V or less at the receptacle is okay, while a few volts or more indicates overloading; 5V is seen as the upper limit.

  • In the US, neutral and earth are bonded in the main panel so voltage should be close to zero. You seem to be in the UK, but 230v from neutral to earth seems wrong. – JPhi1618 Jun 11 at 15:41
  • If an appliance is plugged into that outlet, will it power up? Or does it not work? – Harper Jun 11 at 15:44
  • In the US, 2-wire 240V would be two hots and NO neutral. So where are you? Can you provide pictures of the breaker and the fixture wiring? – manassehkatz Jun 11 at 15:50
  • I've edited the question to provide additional information. – Christopher Taylor Jun 11 at 15:59
  • 2
    Possible duplicate of Acceptable ground to neutral voltage? – Sean Houlihane Jun 11 at 16:33
3

Normal case:

Live-neutral: around 240v

Live-earth: around 240v

Earth-neutral: around 0v

With neutral and live swapped:

Live-neutral: around 240v

Live-earth: around 0v

Earth-neutral: around 240v

So maybe you have a setup were neutral and live got swapped. That's not a safe setup. But to be sure, please check the difference in voltage for all 3 cases.

1

It turns out that the supply polarity was incorrect.

The Line & Neutral had been swapped causing an incorrect reading.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.