Reversed Live/Neutral

[RichA]

It appears that my house is running with a reversed live/neutral.

I had a guy round who used a socket tester and it showed that my sockets have a reversed live/neutral. It is likely this has been the case since last year when I had my CU replaced.

What are the consequences & symptoms of a reversed live/neutral?

Thanks.

 

[BigJon]

I presume his socket tester was up to scratch Did he check the main incoming tails to your consumer unit? if not Get test lamps or a multi meter and check ( safely of course ) that the incoming supply is terminated correctly and polarity is ok.

 

[RichA]

He was a plumber - servicing my gas fire (with electrical start) - so just used a plug in tester. I am going to get the electrician back to give it a proper test.

But was wondering what the effect of this situation is ??? My appliances seem to have been working OK.

 

[JohnD]

The biggest effect is that many of your switches cannot be relied on to make the appliance safe.

This may include trying to make circuits dead by switching off the MCB, as you might do for example to replace a cracked socket or light switch.

 

[danlightbulb]

Since AC power reverses itself all the time anyway (50 times per second), there is no real impact.

The danger is that the fuse in the plug is now on the neutral! So if there was a problem (like someone getting electricuted) the live circuit would not be broken!

Are your lighting circuits the same? If not then its probably a wrong connection in your fusebox.

 

[JohnD]

Since AC power reverses itself all the time anyway (50 times per second), there is no real impact.

no real impact

...except that people can be electrocuted, despite a SP switch being "off", if they touch a conductor incorrectly identified as Neutral, and an earth.

 

[plugwash]

The biggest effect is that many of your switches cannot be relied on to make the appliance safe.

imo the most significant effect is that fuses/MCBs won't protect against faults to earth.

this puts anything not on a RCD at extreme risk.

 

[RF Lighting]

Also the only fuse protection to your circuits in the event of a L-E fault will be your 100A main incomming fuse, which does pose a nice fire risk too.

<edit> Too slow

 

[Spark123]

Agree with above, the a N-E fault on a non-RCD circuit will have to be cleared by the service fuse (100A?). May cause damage to wiring, fire or electric shock. Was it a reputable electrician that did the CU change?
If it is the whole installation with a phase / neutral reversal then I'd have expected it to have been picked up by inspection and testing of the installation as part of the CU change. 16th edition test instruments such as RCD and ELFI testers should not conduct a test with the P/N reversed.
Or on the other hand, the plumbers plug could have been damaged or the individual socket he tested may have been connected wrong??

 

[Taylortwocities]

Yes, check out the original sparky and have a look at teh Installation Certificate he gave you when he changed the CU (you did get one, didnt you.

If he certified the installation with the supply reversed then fry his rear end! Per the above he would needed to have used test equipment that would have picked up the reversal. So if he certed it, he made up the results!

TTC

 

[reggie perrin]

Went to a job recently to change an immersion heater element.

We advanced the E7 timer afterwards to make sure the element would be energised in the early hours but found no voltage.

On further inspection voltage was found across N-E.

The tails were reversed...

 

[Spark123]

I suppose if the meter has been replaced and the eleccy board have made a mistake when re-connecting the tails could be a cause too, then the red and black tails will be in reverse formation.

 

[Jaymack]

One example of dangerous situations that could arise with a reversed polarity: - say a youngster stuck a metal impliment inside a toaster; or an appliance with an open element such as an electric fire. The neutral would be switched; but the element would be live at all times, with a high risk of a fatal accident.

Jaymack

 

[securespark]

have a look at teh Installation Certificate he gave you when he changed the CU

I am going to get the electrician back to give it a proper test.

So, obviously, he did not "give it a proper test" when he did it. Ar..hole!

 

[RichA]

Not sure if I did receive an installation certificate - it was over a year ago.

When I said "get the electrician back to give it a proper test" I was trying to differentiate from the quick test that the plumber did today. I assume and expected that the CU install involved a full test to ensure everything was correct.

I guess I am suprised that if this is the wrong way round that all my electronic items seem to work. i.e. pc, tv, etc ???