NAPIT Codebreakers #12

NAPIT Codebreakers #12

Need help with cracking those EICR codes?

The technical team at NAPIT, with the help of the 18th Edition Codebreakers publication, answer your latest coding queries.

OLLIE TOWNER: I found this installation whilst carrying out a re-wire. The VRI cable is still in use with obvious signs of more recent wiring installations.

Codebreakers: As a general rule of thumb, where Vulcanised Rubber Insulated (VRI) cables are encountered on an EICR, provided they’re still in good order or are adequately contained, they would attract nothing more than a C3.

Where the insulation is found to be crumbling, doesn’t have access to live parts but has the potential for danger, it can be escalated to a C2. In all cases where the cable has degraded, and the conductors can be accessed or touched without any form of barrier, the only option would be a C1.

When carrying out any alterations, it’s always recommended to replace VRI cables. The most contentious areas are when lighting fixtures are being changed, and the VRI cable vaporizes before your eyes; you get that sinking feeling of what to do next.

The insulation in Ollie’s photo is clearly starting to break down, although not catastrophic at this stage. The other wiring present could well have been there when the VRI was more serviceable and not deemed an issue. As this is a re-wire, there’s no problem, and the installation is being dealt with.

From an EICR perspective though, I’d see the VRI as a C3, bearing in mind I’m coding from a photo and can’t see more closely. That said, I’d want to know what the red PVC conductor was doing and maybe consider an investigation to see if a neutral has been borrowed from somewhere else to go with the single red PVC conductor.


SAM GREENFIELD: A builder left the shower cabin and lighting mains supplied via plug tops on an extension lead with tape ‘fixing’ multiple breaks in the cable. No RCD either!

Codebreakers: There are quite a few things to be concerned about here. Before looking at the general construction of the circuits, Regulation 701.512.3 expressly prohibits socket-outlets less than 3m from the boundary of zone 1, unless they are SELV and meet the requirements of 414. Regardless of the shower being a cabin/module, it still falls under these same requirements.

Where tape is used to repair damaged insulation, this is seen as inadequate and repairs must be appropriate to the damage, and/or taken inside an appropriate enclosure. These kinds of bodge repairs are potentially dangerous in any circumstance, let alone in a room containing a bath or shower. Tape notoriously breaks down, goes brittle and falls away, so is never seen as an acceptable means to “repair” the insulation of a cable.

The cable containment isn’t acceptable, and there is likely to be a strain on terminations. Additionally, unsupported solid core conductors could fracture, potentially causing arcing, which could lead to a fire. This is why Arc Fault Detection Devices (AFDDs) are now being recommended by the British Standard.

Using solid core cables connected by a BS 1363 plug isn’t acceptable. This type of plug isn’t designed for solid conductors and has the potential for danger but, in this case, is also overridden by the requirement of 701.512.3. Extension leads shouldn’t be used to permanently connect a piece of current using equipment in this way, especially where the reel of cable isn’t fully extended. Failing to ‘unlead’ an extension lead can cause overheating and is a real potential for fire.

This isn’t directly covered by BS 7671 but the extension lead is effectively now forming part of the fixed installation, so can be coded.

TERRY HUDSON: We found this on a recent EICR for a domestic re-wire: there’s thermal damage, a 2.5 cable coming out of the mains tails for a fused spur, and many other issues that are too long to list.

Codeabreakers: Luckily for the owners of this property, they’ve agreed to have a re-wire and upgrade to the latest version of BS 7671. The list of issues is a long one, and most of them seem to be a fire risk, given the evidence we can see.

The first point of concern for me would be the incoming tails having no barrier inside the CU, and a piggy-backed circuit with no overcurrent or fault protection, clearly showing signs of thermal stress. Several of the other conductors are also showing significant thermal damage, while some are showing signs of repair after thermal damage. Several fuse carriers are also showing signs of thermal damage, and one seems to have burnt severely.

The installation appears to have VRI cables which may well be past their effective life, and appear to have been sleeved in some way, which isn’t necessarily an effective repair. The earthing system is unclear and not entering the metal CU at the same point as the main tails, which may cause eddy currents.

The IP rating of the top of the CU is compromised in multiple areas. The supply tails are also not adequately supported, nor many of the circuits surrounding the CU. Possibly the most innocuous fault here, but the only one to attract a C1.

PAUL LINCOLN: I was carrying out modifications in a school and found this. I always wondered what the third pole was for when used on a single-phase circuit!

Codebreakers: What seems, at first glance, to be an innocent mistake, has the potential for far more. We also have to accept that it may not have been a mistake and there is a real danger that the installer didn’t actually know what the requirements are, which is a concern, especially in complex systems where the correct level of training and experience are vital to ensure safety.

Just because there are spare terminations on an isolator, it doesn’t mean they can be used regardless. It’s not allowed to isolate or switch protective conductors, in this circuit arrangement.

There is a possibility that the live conductors could be energised, as the rotary switch operates from “off” to “on” before the CPC is in circuit, which would leave the equipment without protection for a period that could cause harm. Likewise, if isolating, the CPC may disconnect before the live conductors which has the same potential to cause harm.

It’s only acceptable to switch a protective conductor, under certain conditions, using a particular device. I don’t feel that this installation type meets any of those conditions, nor am I convinced the rotary isolator fulfils the requirements for an isolator for that purpose.

The protective conductor in this case must be continuous and the connection should be made at the highlighted earthing terminal within the isolator, just to the right of the main rotary block

A secondary observation would be the fine wire conductors from what look like HO7 cables. These should ideally be terminated with pin crimps, when used with standard screw terminations. If the terminations were cage type terminals they may be acceptable, but there isn’t enough detail here to give an accurate observation.

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