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

[7029 dave]

Was he on horse back.?

 

[sparkdog]

Looks like the work of Jock MacTavish or possibly Rob Roy MacGreggor.

 

[Midwest]

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

Are you thinking what I'm thinking and probably what everyone else is thinking, or am I being just too cynical suspicious.

 

[The Ghost]

thinking what I'm thinking

Mhmmm!

 

[Pete999]

I thought what you are thinking last night, but then I thought Nah can't be, then I thought yes we all could be right

 

[telectrix]

thing is, everything will work OK, but should you switch something off at it's switch, it will be switching the neutral instead of the line, so there is a potential, if not immediate, danger. have you had a new meter installed lately?

 

[Vol]

The CU was changed on Friday of last week, the 28th April.
The electrician is coming over on Monday to resolve the problems.
Surely the RCD on a new CU is active on both live and neutral? Whereas it might not pick up a complete line reversal cos "things remain in balance wrt earthing", surely it would pick up a fault even on the neutral line? Does the RCD switch off both lines or just the presumably live line? If only the live line, then that doesn't seem like a well planned solution to me - for an RCD device to be fully safe, it has to switch off both live and neutral, or am I misunderstanding? It is dealing with a fault, how does the RCD know the nature of the fault, it's job has to be to cut off any possibility of current reaching the device or appliance, that should mean cutting off both live and neutral, in my humble opinion.
The point raised by mache about a faulty washing machine etc continuing to be live due to the neutral line issue is worrying. Won't the earthing system within the appliances keep the outside surfaces safe though? Also the issue of the Edison screw bulbs having a live screw casing is worrying too, although we have few of those and nobody will go near them until the electrician has done his stuff.

 

[Pete999]

The CU was changed on Friday of last week, the 28th April.
The electrician is coming over on Monday to resolve the problems.
Surely the RCD on a new CU is active on both live and neutral? Whereas it might not pick up a complete line reversal cos "things remain in balance wrt earthing", surely it would pick up a fault even on the neutral line? Does the RCD switch off both lines or just the presumably live line? If only the live line, then that doesn't seem like a well planned solution to me - for an RCD device to be fully safe, it has to switch off both live and neutral, or am I misunderstanding? It is dealing with a fault, how does the RCD know the nature of the fault, it's job has to be to cut off any possibility of current reaching the device or appliance, that should mean cutting off both live and neutral, in my humble opinion.
The point raised by mache about a faulty washing machine etc continuing to be live due to the neutral line issue is worrying. Won't the earthing system within the appliances keep the outside surfaces safe though? Also the issue of the Edison screw bulbs having a live screw casing is worrying too, although we have few of those and nobody will go near them until the electrician has done his stuff.

 

[Vol]

Some information to add, On May 16th the electricity company (the main electricity infrastructure company not the name on the electricity bills) comes to upgrade the supply side meter at the close mouth (for those that don't know, close is the entrance way to a Glasgow tenement). That will be upgraded in order for me to have SMART gas and electricity meters installed. This, with the CU replacement, is part of the general upgrade of systems in the house.
The supply side upgrades will include a new isolation unit as the existing fuse box with the big ceramic cartridge fuses is well out of date. I obviously don't actually know what they will be changing/installing as they don't share that information with me, of course!

 

[Octopus]

As a final check before leaving, the electrician inserted a socket tester. In every location tried, the socket tester showed L&N Reverse.

Hum..... what proper tests did he do?

 

[westward10]

Modern ES lamp holders are not polarity biased. Coming back Monday!

 

[Vol]

Love the video, not least cos it reminds me of the times I worked with Australians in the Far East! Maybe I didn't pick it up but is it answering my question - surely the CU RCDs are monitoring both live and neutral for faults and when a fault occurs the RCDs will shut down any possible current in both live and neutral?

 

[Vol]

Hi Murdoch, the answer now seems to be obvious: what proper testing did he do? Either none or not enough

 

[telectrix]

The CU was changed on Friday of last week, the 28th April.
The electrician is coming over on Monday to resolve the problems.
Surely the RCD on a new CU is active on both live and neutral? Whereas it might not pick up a complete line reversal cos "things remain in balance wrt earthing", surely it would pick up a fault even on the neutral line? Does the RCD switch off both lines or just the presumably live line? If only the live line, then that doesn't seem like a well planned solution to me - for an RCD device to be fully safe, it has to switch off both live and neutral, or am I misunderstanding? It is dealing with a fault, how does the RCD know the nature of the fault, it's job has to be to cut off any possibility of current reaching the device or appliance, that should mean cutting off both live and neutral, in my humble opinion.
The point raised by mache about a faulty washing machine etc continuing to be live due to the neutral line issue is worrying. Won't the earthing system within the appliances keep the outside surfaces safe though? Also the issue of the Edison screw bulbs having a live screw casing is worrying too, although we have few of those and nobody will go near them until the electrician has done his stuff.

a RCD senses an imbalance between the L and N current. a difference of 30mA ( 0.03A) is the standard rating for domestic shock protection. most RCDs disconnect both L and N ( double pole ) . the theory behind this is that, should you be in contact with a live part of the installation, this causes the imbalance, so the RCD trips.

 

[Vol]

Does anyone know an answer to the other question? Is the new CU work notifiable under the Scottish regulations?

 

[Vol]

At the risk of offending the many kind souls on here who have given their best advice and caveats, I am a bit concerned about what amounts to trolling by another bunch of "thinkers" who have their "suspicions". If you have nothing positive or constructive to say, you should avoid taking part, otherwise you are just cluttering up the place. If you have a real suspicion of something germane, then speak up and give your evidence.
Back in the day, when I had the eyesight and the hands without arthritis, I would tackle many jobs around the home. A socket extension? No worries. A new light. No problem. This is back in the day when it was legal to do so and you didn't have to worry if you were a skilled, instructed or ordinary person! But installing a new CU? Never would have dreamed of attempting that even back then (not that they had CUs back then anyway !!!) and nowadays I most certainly would never, ever consider attempting to swap an old fuse box to a new CU, where would a I even start for goodness sake??? So if that is what you think, think on, that's your prerogative. But I joined this forum in the hope of getting some good advice about a partiuclar problem created (or left unattended) by an electrician I paid. I anyone wants to read beyond these fairly simple facts, then be your guest.
Thanks again to the many people who have given me their considered advice and input.

 

[Vol]

Just a small add on to the discussion of the electrician's work. At one point during the install he said he would not be able to pass the new CU installation cos the meter tails were only 16mm and they had to be 25mm. He said he would come back and install the new tails foc and provide the paperwork then. As it happened, my wife was out then near to a Screwfix so I ordered online and she collected so the electrician was able to install the new tails. But the paperwork was lost a bit in the rush at the end.
My point is that in some ways the electrician was indeed conscientious and professional. Though obviously not in every way.

 

[Octopus]

A small point of order.... The tails do not HAVE to be 25mm...It all depends on the size of the main fuse

 

[Specialist]

Well, this has been a long & unusual story. A good read, but sadly I've gotta leave.
Have to go Wind up my old watch before going out.

 

[Wilko]

Love the video, not least cos it reminds me of the times I worked with Australians in the Far East!

Sounds part Irish part Aussie to me, but they did a good job editing the expletives out of the video. Experience tells me there would have been considerable colour around the time of the fault