Fly Leads For Swa On A Metal Clad Db

[Industspark]

Once again after some knowledge from some wise old men.
As per photo, I have been issued from a contractor a C2 for 'The MICC/SWA or earth bar cables earth system is incorrectly connected.'
I have 26 metal clad consumer units with this C2 where the earth tag has been fitted with nut & bolt. However, because there's not fly lead going to the earth bar as the top of DB can be removed using tools,they've not specified a regulation but say it's incorrectly fitted.
Others include the earth stud not being connected, which I believe is there for bonding not to connect main earth to.

My question is, If its a metal clad DB are fly leads required( what reg) if the lid is designed with removable top surface with use of a tool.( nut & bolted)?
Many of the installations were constructed to BS 7671 15th & 16th edition.

 

[Industspark]

I'd say 543.2.6 allows the consumer unit metal clad surface to be used. Painted surface isn't a issue as earth tag (banjo) has been nut & bolted.

 

[Lucien Nunes]

Banjo bolt will only make good connection if paint has been stripped, otherwise it will be no better than the gland nut. Is there a gasket under the gland plate?
The regs aren't so prescriptive as to say a fly lead is or isn't required, it's a matter of whether the particular piece of work in front of you makes a sound connection. The devil is in the detail and we can't see that from here. I never rely on steel fixing screws alone, I would always fit a nickel-plated brass bolt lock-nutted through the banjo etc or use a Piranha but that is my personal preference. Clean BZP steel screws tightly fastened through a gland plate in a low-corrosion enviroment can make a decent connection.

 

[Deleted member 26818]

Has the earth continuity on these cables been checked?
The requirement is just to earth, not to use a particular method.
If ther is earth continuity and the Zs is low enough to allow the OCPD to operate, I cannot see a problem.
However best practice would to my mind be to have used a fly lead, just the same as with metal back boxes.
To my mind, unless there is no, or poor earth continuity, there is no call for a code C2.

 

[Industspark]

The continuity has been checked and very low.And yes it may be best practice to fit flyleads but most these DB's were fitted over decade ago some 20 years.
Banjo has been fitted, drilled and bolted.
My issue is I have to go to site manager and he's not going to accept its just against regulation, he will require a actual regulation number and why its a C2 after 20 years of being ok.
He's an engineering manager and quite a intelligent chap. To shut down a 24 hour site to do the repairs when should be a C3 at most I'd like to either send report back saying it's within regulation or to go in knowing It's the right thing to do.

 

[Industspark]

 

[Darkwood]

Two points to mention here, as its a removable gland plate then the integrity of the earthing relies on the self tapping screws holding the plate down to the panel (although in your example there are fly tail already connected that may give a better route to earth), had it been a solid construct panel and adequate measures had been taken to give good contact like serrated washers then it may have been acceptable, (not the case in the example pictures). My second point is regarding taking earth loop readings, you are sending a low DC current through this quesstionable connection, this will show you a given reading that the earth path exists or not but it cannot be relied on totally to make a judgement call, normally in fault <1000 amps will flow and if it passes through a weak spot as above could be then that can create high resistance or breakdown which may cause the OCPD to operate out of permitted trip times, this could lead to damage to the cabling of the circuit and the integrity of isulation.

These boards probably just require a serrated washer on the inside and a common fly lead looped to the bonding terminal, I see no reason to power down and stop production as these boards are designed with finger protection and isolated stubbs, so unless you have other reasons to need to power down the full board then I cannot see why a professional who is aware of the dangers within this board cannot leave them energised while the work is done, this is where the stupidity of H&S red tape tramples on common sense and actual risk, use a risk assessment and if you don't see any immediate concern like exposed or damaged conductors that would increase the risk then just plan it as a routine job.

 

[Industspark]

Two points to mention here, as its a removable gland plate then the integrity of the earthing relies on the self tapping screws holding the plate down to the panel (although in your example there are fly tail already connected that may give a better route to earth), had it been a solid construct panel and adequate measures had been taken to give good contact like serrated washers then it may have been acceptable, (not the case in the example pictures). My second point is regarding taking earth loop readings, you are sending a low DC current through this quesstionable connection, this will show you a given reading that the earth path exists or not but it cannot be relied on totally to make a judgement call, normally in fault <1000 amps will flow and if it passes through a weak spot as above could be then that can create high resistance or breakdown which may cause the OCPD to operate out of permitted trip times, this could lead to damage to the cabling of the circuit and the integrity of isulation.

These boards probably just require a serrated washer on the inside and a common fly lead looped to the bonding terminal, I see no reason to power down and stop production as these boards are designed with finger protection and isolated stubbs, so unless you have other reasons to need to power down the full board then I cannot see why a professional who is aware of the dangers within this board cannot leave them energised while the work is done, this is where the stupidity of H&S red tape tramples on common sense and actual risk, use a risk assessment and if you don't see any immediate concern like exposed or damaged conductors that would increase the risk then just plan it as a routine job.

Reason mention power down was the report states for corrective actions ' To isolate supply, fit fly leads to each SWA. I also believed the common earth to be adequate. The only thing I saw wrong with this DB and the others similar is that no washers. however, after a phone call with the inspector he hadn't even noticed that.
I have 300 reports with unsatisfactory condition. All C2's. Many of which I'd class as C3's. example C2 for no evidence of RCD testing although there's 5 years of annual and functional reports to hand and many more in archive.
C2 for no chart etc.
These as 2391 & 2394/2395 qualified myself would class as C3.
Having a huge bill come through for remedial works as a total rather than broken down also for immediate repairs required.

 

[timbobelfast]

Flyleads for me if this is a clearance hole.
If the on-site engineer permits you to take the covers of energised then no need to disconnect the existing bolt, install your fly lead using and additional brass nut and brass washers and connect to the earth bar.

 

[Darkwood]

Reason mention power down was the report states for corrective actions ' To isolate supply, fit fly leads to each SWA. I also believed the common earth to be adequate. The only thing I saw wrong with this DB and the others similar is that no washers. however, after a phone call with the inspector he hadn't even noticed that.
I have 300 reports with unsatisfactory condition. All C2's. Many of which I'd class as C3's. example C2 for no evidence of RCD testing although there's 5 years of annual and functional reports to hand and many more in archive.
C2 for no chart etc.
These as 2391 & 2394/2395 qualified myself would class as C3.
Having a huge bill come through for remedial works as a total rather than broken down also for immediate repairs required.

The serrated washer would be for a situe' where a fly lead wasn't necessary but you needed a reliable contact, I suggested still putting one on as it would stop the nut from loosening with time if its subject to any form of vibration etc, this could equally be achieved with a spring loaded washer or if your lack these then doubling the nuts up can be a solution, the spring loaded would be your best approach using a second nut as this means you wouldnt be disconnecting the earth path on a live circuit, I would issue your own risk assessment and submit it to the powers who be that these corrective measures can be done without power down lthough a small risk of accidentally knocking a mcb off does exist when fitting or removing the cover, although re-itterate that it is a small risk unless you note the MCB's are poorly fitted and don't fully line up with the lid cutouts.

 

[The Ghost]

I know this thread is a bit old. However we are pontificating on the exact same problem. Only in this case there are 40 office metal clad DB to do and 40 clients to disrupt. I cant quite get my head around what we are trying to do here. In our case the earth is supplied in the three core L-N-E. The armour is not the earth supply. So we think no problem then ? But working on lights above the suspended ceiling, I have received a shock between the grid and the earth in a unit in two separate buildings. Measuring the voltage received it is 120v. We bonded the metal box to earth and the voltage disappeared, in one of the buildings. However in the other it turns out it was due to a neutral being connected to earth at one lighting point in a chain of 18 external emergency lights. We are still puzzling over this thinking perhaps a loose neutral?

 

[Wilko]

Hi V - sounds like it - otherwise you are running with a neutral 120v above gnd? You have found one implementation error, there may be more. The Inspector in me says test the installation. Better than another surprise.
On the earlier DW #24 post (tin hat on) ... Wouldn't we have to power down to release the cable from switchgear to slip the extra nut or washer on? Still no coffee here so I may have lost the plot

 

[Pete999]

I would have thought that good workmanship applies when terminating glands, conduit etc to a metal enclosure, what happened to cleaning the paint and making a nice shiny surface to fix to. In my day we used to clean the ends of conduit couplers, and both inside and outside of metal enclosures, guess they don't teach that on these Mickey Mouse courses. Do them up tight with a fancy bush spanner, sorry I'm ranting again.

 

[The Ghost]

We are in the process of EICR rectifications all over as we speak

 

[The Ghost]

would have thought that good workmanship applies when terminating glands, to quote Pete
These boxes were put in 20 years ago, not sure on the designers/installers thinking leaving out fly leads on this one. Maybe they did clean of paint and fix to bare metal.

 

[Deleted member 26818]

Good workmanship to my mind, does not entail doing something that is unnecessary.
To my mind in many cases SWA is an over specification for the purpose the cable is intended to provide.
Drilling holes and installing fly leads is often just work for work's sake.