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WARREN GILL: THIS PHOTO IS OF A SUBMAIN WITHIN A BARN, WITH MULTIPLE SUB MAINS TAKEN FROM THE SUPPLY CABLE TO THE PICTURED CONSUMER UNIT. IS THAT THE SWA ENTERING BOTTOM RIGHT, WITH TWO OTHER SWA CABLES TO OTHER CONSUMER UNITS BEING THE OTHERS? INTERESTING!
Unfortunately, some of the poorest installations and lack of competency can be found in agricultural buildings and farm premises across the UK. The picture above shows a complete disregard for electrical safety and is also at risk of overload and potential fire.
What we initially see is the incoming power, the bottom SWA, doesn’t appear to have a circuit protective conductor (cpc). The armour may be the cpc, but that isn’t known from the picture, as there is no fly lead connection, and this is a plastic board. If the intention was to isolate the incoming Earth from the sub-board and create a TT Earthing arrangement, the earthing conductor to the Earth electrode could be the larger 10mm2 + cable connected to the MET. There is a requirement for a circuit to have a cpc throughout its length, Reg 4126.96.36.199, so the inspector will have to check that the incoming SWA fulfils this requirement.
While we’re looking at the MET, it would appear that the two sub-board supplies have the black SWA conductors attached, but not marked as the cpc, which is also a requirement of Reg 514.4.2. The incoming supply Line conductor (bottom right) is also using a Neutral connector block of what was originally a dual RCD high integrity board. This is incredibly dangerous as there are now terminals that are at Live potential, which are not expected to be. This re-configured neutral bar is then used to supply the CU itself and the two external sub-boards.
The two sub-boards now possibly have no overload or fault protection, depending on the CU supply characteristics. If the incoming supply has been made into a TT Earthing arrangement, the two sub-board supply cables have no protection. If the incoming supply is not TT, then there is no protection, because the cpc may not be extended to the CU, in which case the supply cable protection won’t be protecting the two sub-board supplies either. It is a requirement of Reg 415.2.1 that the armour of an SWA cable is connected to the cpc, as the gland and initial stranding are considered to be exposed-conductive-parts if they’re not used as the cpc. Neither of the two sub-board supplies appears to have their armour connected to the cpc, and therefore likely don’t comply.
It is expected that to isolate the two out-going, and any final circuits, it would only be required to operate the CU main switch; however, this is not the case. The supply to the CU would need to be isolated to make it safe, which is extremely dangerous, as to not do so would leave the aforementioned “neutral” bar still Live.
The re-configured “neutral” bar and it’s now Live potential conductors pose a threat to the floating disconnected circuit within the CU. There is a potential that these disconnected conductors could come into contact with the now exposed Live, “neutral” bar, so this must also be looked at for coding.
This is/was originally an MK board, but has had a Schneider RCD fitted, so we need also to code for mixed components within an Original Equipment Manufacturers (OEM) enclosure. Regardless of any mixing issues, and there appear to be no thermal issues at this point, the connection of the RCD Neutral conductor is of great concern. Without further knowledge of the install, the RCD Neutral conductor looks as if it is either:
1. Not connected properly into the RCD supply terminal, or
2. Not connected at all, possibly because of unwanted tripping, or
3. Not connected because the connection to the actual Neutral bar is via the out-going side of the main switch
When we look very closely at this picture, I suspect that item 3 here is the method of connection, which may render the RCD non-operational, which means that some final circuits of the CU may have no additional protection in accordance with Regs 415.1, 411.33 or 705.411.1.
As this is likely to be a TT Earthing system, although not confirmed here, there is a preference to ensure protection via an RCD in accordance with 411.5.2(i), which will not have been met here if the RCD is not in circuit and operating correctly.
All in all, a truly shocking and dangerous installation!
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