There’s debate about exposed basic insulation in meter cupboards being satisfactory or not? Industry guidance (WRAG) say it’s satisfactory if the door’s in good shape, what’s people views on this ?
There’s debate about exposed basic insulation in meter cupboards being satisfactory or not? Industry guidance (WRAG) say it’s satisfactory if the door’s in good shape, what’s people views on this ?
There’s debate about exposed basic insulation in meter cupboards being satisfactory or not
Its a C2 from me. As is shoddy SWA termination or lack of.
SWA needs to be terminated correctly and double insulation cables SHOULD be present. Some people would say this is insulation and mechanical protection but most people call it Double Insulated. There is also a Deflecting argument of
Is a meter cabinet an electrical enclosure?
People need to look at this in 2 distinct scenarios
- Domestic Dwelling with outdoor meter cabinet, of which there are 2 variants, In Wall and On Wall
- Domestic dwelling with indoor cabinet
Other scenarios are also available like industrial or commercial but I will focus on UK domestic dwelling to make it easier
Domestic Dwelling with outdoor meter cabinet
- Risk of UV degradation
- Risk of Impact or Damage
- Risk of door being removed/severely damaged by bad weather or person making the term enclosure or cabinet compromised
- Risk of Children or Disable/Lesser-abled person or mentally impaired person making contact. Normally meter cabinet/cupboard height dependant
- Risk of unskilled person or homeowner needing access to the content of meter cabinet for legitimate reasons like read meter or Isolation in the event of a fault or fire.
- Risk of malicious intent like vandalism or common criminality
- There are other points of consideration as well so this list is not exhaustive.
Domestic dwelling with indoor cabinet
- Risk of Impact or Damage lowered but NOT eliminated. A lot of UK home have the point of original under the stairs in an average house
- Risk of Children or Disable/Lesser abled person or mentally impaired person making contact. Normally meter cabinet/cupboard height dependant
- Risk of unskilled person or homeowner needing access to the content of meter cabinet for legitimate reasons like read meter or Isolation of a fault or fire.
- There are other points of consideration as well so this list is not exhaustive.
With the above being said the outdoor scenario carries a higher inherent risk due to external influences like weather and physical damage and possibly animals. Now let’s consider the above 2 situations under normal working/operating conditions and under fault conditions. As a casing point who in the UK has see a meter cabinet with a missing front door? Or cabinets/cupboard with a pool or pooling of water inside?
Other points to consider or discuss between the community and IET, BSI and ENA (Energy Network Association) is that when SWA (Steel Wire Armour) is used into the outdoor cabinet/cupboard then there should be A Designated Entry point into the meter cabinet.
Eg Domestic Dwelling outside ON Wall meter cabinet then ONLY bottom entry is allowed in right hand corner.
Eg Domestic Dwelling outside IN Wall meter cabinet then ONLY rear entry is allowed in lower right hand corner.
Entry points need to be discussed further as the Bend Radius for SWA is quite different to Flexy Tails or Split Concentric cable.
All meter box penetrations MUST be from Below or REAR and MUST/SHALL be Gasket or INTUMESCENT SEALED. SIDE or TOP penetrations are FORBIDDEN into the meter cabinet/cupboard.
IF SWA is used in the meter cabinet/cupboard then it MUST be Terminated correctly, this may take the form of an approved glanding into a WISKA box (other brands are available). There MUST NOT be SWA single insulation on show. Non approved SWA glands are FORBIDDEN. The same applies to Split Centric cables. The Split Con MUST be terminated correctly or to manufacturers instructions.
In summation the meter cabinet SHALL have cables that ARE double insulated to provide an extra safety layer, protecting Property, People and Live Stock on the CUSTOMER SIDE with a functional and intact door. If it does not then I refer you to NASA and the document they published called
Normalization of deviance
Definitions and interpretation again!
Enclosure. A part providing protection against certain external influences ... ticks that box ... and in any direction providing basic protection. Not sure about that.
Basic protection. Protection against electric shock under fault-free conditions. NOTE: For low voltage installations, systems and equipment, basic protection generally corresponds to protection against 'contact of persons or livestock with live parts'.
This thread is about exposed basic insulation.
Basic insulation. Insulation applied to live parts to provide basic protection ...
Given that the live conductors already have basic insulation, and accordingly, basic protection, the meter cabinet can hardly be providing it as well.
If there is, for example, a REC2 in there, the actual switch sits in its own enclosure, otherwise its terminals would be exposed. I suggest that the cabinet's purpose is to protect the DNO's tackle from the weather rather than to protect persons (and livestock) from it.
Given that the live conductors already have basic insulation, and accordingly, basic protection, the meter cabinet can hardly be providing it as well.
I'm not sure I follow, in terms of Regulation 410.3.2. Isn't the point that the combination of "enclosure + basic insulation" is providing the equivalent of double or reinforced insulation (it's basic protection + mechanical protection) per Regulation 412.2.2.1?
What happens when the door to the cabinet is missing or damaged
Same as if any other item of electrical apparatus is damaged... other than considering if it was suitable for the conditions in the first place, it's just life - hopefully people will be sensible enough not to use damaged equipment or keep their fingers out if it can't be de-energised, and it'll be picked up by the next inspection.
I do agree though that I don't consider a meter box to be an "electrical enclosure" in the same sense as say a joint box - on the basis that ordinary persons have good reason to access the inside of it. The problem we have is that the words in the regs seemingly don't justify that common sense (?) point of view.
- Andy.
Maybe the next amendment/edition of BS7671 can clarify that an OUTDOOR meter box/cupboard is NOT the same as a Electrical Enclosure because
The average Un-Skilled person would not normally enter an electrical enclosure, but they DO enter the OUTDOOR meter cupboard/cabinet for legitimate reasons like to read the meter or top up the meter on a prepay or to advise the DNO of the flashing light colour during a power-cut.
This still leaves open the debate about the SWA not being terminated correctly and WHY a meter cabinet/cupboard does not mandate that ONLY rear or bottom entry with the penetration being correctly seeled. Entry points need to be discussed further as the Bend Radius for SWA is quite different to Flexy Tails or Split Concentric cable.
Below is my attempt at some possible wording.
All meter box penetrations MUST be from Below or REAR and MUST/SHALL be Gasket or INTUMESCENT SEALED. SIDE or TOP penetrations are FORBIDDEN into the meter cabinet/cupboard.
IF SWA is used in the meter cabinet/cupboard then it MUST be Terminated correctly, this may take the form of an approved glanding into a WISKA box (other brands are available). There MUST NOT be SWA single insulation on show. Non approved SWA glands are FORBIDDEN. The same applies to Split Centric cables. The Split Con MUST be terminated correctly or to manufacturers instructions.
In summation the meter cabinet SHALL have cables that ARE double insulated to provide an extra safety layer, protecting Property, People and Live Stock on the CUSTOMER SIDE with a functional and intact door.
I accept that a meter cabinet is capable of providing the supplementary insulation portion of double insulation, but then care would be needed with the earthing conductor.
If the MET were in the distribution board and connected to the service head by a length of G/Y, all well and good; but if the traditional MET consisting of a steel block with two rows of screws, especially with a TN-S supply, is in there, it needs to be insulated and marked (412.2.2.4).
Or it simply is not an enclosure.
If the door has fallen off, or the lock is broken, then it's not an enclosure any more.
Yes, ordinary consumers can and do open meter boxes. The risk is really very low provided everything inside has basic insulation.
I do agree though that I don't consider a meter box to be an "electrical enclosure" in the same sense as say a joint box - on the basis that ordinary persons have good reason to access the inside of it. The problem we have is that the words in the regs seemingly don't justify that common sense (?) point of view.
Could BS7671 regulation 416.2.4 exclusion or note section say something like
A domestic dwelling meter cabinet is NOT considered an enclosure
Could BS7671 regulation 416.2.4 exclusion or note section say something like
A domestic dwelling meter cabinet is NOT considered an enclosure
I could, but I'd prefer a more robust approach - as it stands people can claim all sorts of things with a lock of held together by screws are acceptable as an electrical enclosure ... meter boxes are but one example - the same could be said of anything between bath panels and broom cupboards. Hence my suggestion that the definition be limited to "dedicated" electrical enclosures - i.e. things that need to be opened only for the purposed of electrical work (installation, alteration, testing etc.) and not for other purposes. Where there's a need for the unskilled/unsupervised to have access, it wouldn't count.
I wouldn't object for this "clarification" to take the form of a note, rather than the main definition, if it was easier to introduce that way,
- Andy.
Listening to a recent podcast they raised an interesting point. IF the meter cabinet is an enclosure then should it have the yellow warning stickers/labels on the outside stating 230 volts LIVE?
Listening to a recent podcast they raised an interesting point. IF the meter cabinet is an enclosure then should it have the yellow warning stickers/labels on the outside stating 230 volts LIVE?
IF the meter cabinet is an enclosure then should it have the yellow warning stickers/labels on the outside stating 230 volts LIVE?
BS 7671 doesn't generally require 230V warning stickers - and I suspect there would be quite a backlash from the "aesthetics brigade" if we required such stickers on all enclosures (including sockets, switches, joint boxes, CUs...)
- Andy.
We're about to take you to the IET registration website. Don't worry though, you'll be sent straight back to the community after completing the registration.
Continue to the IET registration site