New Consumer Unit Installation - L&N Reverse at the sockets

[Pete999]

Hi there, I'm a newbie to the forum. I'm an ordinary senior citizen householder but while not an electrician, I do take notice and read up on all the stuff the electricians are doing in my house. I have just had a modern, metal consumer unit installed after the removal of the old traditional fuse box. The installation went pretty well with very few curses! Given the old wiring in the house, everyone was pleasantly surprised when both RCDs stayed good and the supply uninterrupted.
As a final check before leaving, the electrician inserted a socket tester. In every location tried, the socket tester showed L&N Reverse. I bought s socket tester and confirm the same readings: L&N Reverse. I haven't checked every single socket but that is the pattern.
One problem is that I have no way of telling if the old fuse box situation would have given the same L&N Reverse readings, ie did the electrician change anything or just carry on an existing (hidden) error?
Firstly, is this in any way a dangerous situation given the RCDs are quite happy? If dangerous, what should be done immediately?
Secondly, how could this reversal have occurred? The electrician simply reinserted the live and neutral cables appropriately as they were removed. The meter tails were changed cos the existing were only 16mm. Could the tails have been reversed somehow?
Anything else you guys can suggest?
Thanks for reading the newbie panic post! I would appreciate any input, thanks..

He, the Electrician, let you with reversed polarity? yes he should have rectified the fault Imediatly

Hi Rob, thanks. The very reason I am asking these questions on this forum is because I am aware already of the potential ramifications of a dodgy installation. Everyone seems focused on questioning the parentage of the electrical installer (and by implication, my own sanity for contracting with him in the first place), whereas what I really really want to know if the L&N Reversal is (actually and actively) dangerous and what to do if it is. Secondly, I would like to know how the problem might have arisen (and thus how it may be resolved) and thus be better informed when that, or another more like, electrician comes back to put things right.
I take your point about these little plug in devices. There should have been a more systematic testing of the circuit. But honestly,
I felt secure with the safe operating presence of the RCDs which I understood rightly or wrongly was one of the fundamental bases of the most recent code.
Thanks again for your input.

Wow, I'm so impressed and grateful for the comments and advice! (NB I found myself sounding a bit defensive in my last posts but I'm not really.)
The consumer unit is a BG 16-Way Dual RCD Metal Consumer Unit & 12 MCBs sourced from Screwfix. It seems to have a decent enough reputation and seemingly ticks all the boxes.
If Part P doesn't apply in Scotland (where I am located), is the work there still notifiable in some other way?
I know it is almost impossible for qualified electricians to say, yeah, go on, it's probably safe. However, is there any substantial reason why my usual electrical load through fridges, washing machine (cool washes only), dishwasher (wash programmes only, no drying), TV etc should not continue over the weekend? If I cannot find an electrician to come out over the weekend, then it would be first thing next week. Does that timescale sound OK?
Thanks again, you've been very helpful.

Vol, you need to, contact this Idiot, he is a Muppet for leaving you in this predicament, as others have said reversed polarity could be potentially dangerous, I take it you have paid him? Sorry for the sentence in between don't know what happened there

 

[Vol]

I've just checked and it seems that the L&N Reversal is prevalent in every socket across every zone in the house. Does that imply that the problem could well be at the "source" maybe the swapped meter tails?
I see the point that if the socket is switched off, the connection might still be live under a reversed polarity situation. One of my first purchases when I recently bought the house and saw the inaccessibility and age of the old fuse box, was 10 large automatic lights, the kind that go on only if the electricity supply cuts. These are currently (no pun intended ) behaving "normally", ie they are off until the socket is switched off. Does that mean that polarity doesn't matter to these lights or that the socket switch IS switching off the live feed?

 

[Des 56]

What prompted you to go out and buy a socket tester thing
I ask because,it seems a unusual action for a customer,seems to be a needless expense in most circumstances as well

 

[Ian1981]

If the meter tails are reversed polarity then all your circuits will be subject to live - neutral reverse.
Ring him and threaten to take him to trading standards if it's not rectified immediately.
His arse might just twitch a bit!

 

[Vol]

Pete999, I think it is Muppets all round in this case, him and me. But this electrician talked a good game, professed 17th Ed tested/qualified and although I'm not an electrician I have been around electrical work all my life from my Dad (electronics engineer) on. I'm actually very safety conscious and regulations aware. And he was hard working and conscientious - right up to the reverse polarity issue I accept . However, until the industry has a similar scheme to Gas Safe then these problems will continue to occur I suppose.
OK, the problem will be resolved early next week and much care will be taken between now and the fix.
Thanks again

 

[KennyKen]

Am I reading this thread correctly? Am I right that the so called spark has left knowing that there is reverse polarity between live and neutral? Sod the other appointment and sort yours... "supriced when he turned the RCD's on" oh geez I need to sleep

 

[westward10]

Sounds like reverse polarity at the consumer unit. This should be rectified immediately and if he isn't willing to resolve this ASAP then threaten him with legal action and get another electrician in to resolve the issue and get some kind of written evidence to use against the original installer.

 

[Vol]

Des56, I didn't just go out and buy a socket tester thing. I looked up the kind of testing that an ordinary consumer can undertake by themselves and this socket tester device was suggested. If it read the same as what the electrician had found, then I had at least proved it was not a single device fault. I didn't go out at all. I ordered it online.
But you seem to be implying something, I'm not sure what. You say "I ask because it seems such an unusual action for a customer". The product I bought had over 1000 purchases and a 4.9 out of 5 stars from 64 reviewers. What else is available for an ordinary consumer who is concerned about an electrical function/socket?
Everyone else today has given good advice and everybody on this thread talks like a good professional. But so did the electrician who came to me. On the doorstep, how is the consumer meant to be able to tell who is the competent professional as apart from the incompetent professional (as an earlier poster talked about).

 

[Vol]

Thanks for all the helpful inputs, I really appreciate it. I'll try to update the thread when the problem is resolved next week. Thanks again.

 

[Bob Geldoff1234]

Can you take a picture of the consumer unit and the tails going into the meter?
We might be able to help if we can see the unit.

On the note of if a person is competent then being an Approved NICEIC electrician(or similar) is a start.I know alot of people on here don't like the relevant schemes but in order to be in them,you have to prove your qualifications,have insurance in place,have your test meters calibrated and pass a yearly inspection.While none of the above proves that you'll get a quality job,it does at least prove that the person your hiring has obtained the skills to become approved.Unlike the bloke down the pub who does a bit of electrics on the cheap.

 

[Des 56]

I asked because it is the first time in 50 years that I have heard of an installation being left with a known reverse polarity issue
Its the first time I have known of a customer, having been made aware of the problem, then sourcing electricians test equipment to check an installation constructed by another
I asked.you answered,thank you for the response

 

[Andy-1960]

I take it the isolation of the supply to the property wasn't carried out by the DNO ?

 

[mache]

To answer you question on relative safety at this time. The line and neutral reversal is a problem if you have a secondary fault occur before the situation is resolved. As an example should your washing machine develope a fault. It is possible the plug fuse will blow but this will only disconnect on the now neutral line. There will remain live power feeding into the machine. My advice until the situation rectified would be to unplug any metal cased equipment you have where ever possible. E.g. washing machine, dish washer etc any any equipment you do not required powered up. No one can guess if or when a fault may occur.
I am not a professional electrician by the way but I believe I am correct in my thought process. I am sure others can confirm or correct if necessary.

 

[Wilko]

Pete999, I think it is Muppets all round in this case, him and me.

Vol, no way this is your fault ... End of.

 

[gazdkw82]

He is not an electrician if he left you with reversed polarity after changing your CU.

It's not a difficult problem to figure out and most likely is something to do with the installation process of the CU.

The fact that he only noticed reversed polarity after plugging in a tester says to me he's not even done the basic testing required for this type of work.

Just can't believe it's been left like that

 

[Andy-1960]

To answer you question on relative safety at this time. The line and neutral reversal is a problem if you have a secondary fault occur before the situation is resolved. As an example should your washing machine develope a fault. It is possible the plug fuse will blow but this will only disconnect on the now neutral line. There will remain live power feeding into the machine. My advice until the situation rectified would be to unplug any metal cased equipment you have where ever possible. E.g. washing machine, dish washer etc any any equipment you do not required powered up. No one can guess if or when a fault may occur.
I am not a professional electrician by the way but I believe I am correct in my thought process. I am sure others can confirm or correct if necessary.

Fuses will only blow in the event of overcurrent fault, faults to earth will not cause fuse to blow because they are effectively not in circuit. RCD's will continue to operate in the event of a live to earth fault, but some RCD's only break on one pole, so in this situation the circuit would still remain live.
Circuits not protected by an RCD will only have to fuse in the cut out (100A?) as protection, which could cause a major fault, fire, etc.
Also remember any Edison screw light fittings will be backwards so the threaded part will now also be live.
I cannot believe this 'electrician' has cleared off for the weekend and left this.. it needs to be addressed now

 

[Pete999]

Vol, no way this is your fault ... End of.

Correct not your fault.

 

[Bob Geldoff1234]

With the correct test instruments then its pretty easy to determine where the live neutral reverse has taken place.Even if the bloke had an appointment then fixing this kind of fault wouldn't have taken long to find if you have the experience.I agree with everyone else's opinion ,that it needs sorting asap.

 

[gazdkw82]

It has to be all the sockets reversed or else there would a short circuit somewhere. I'd say the wholes system is reversed at the tails or the RFC is wired incorrectly at the board.

Again, proper testing would easily determine the issue.

 

[Octopus]

Out of interest when was the CU changed?