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Consumer unit in external meter box.

IronFreely

I’d like to ask for some advice on an unusual EICR observation. Domestic bungalow, the installation has the main consumer unit installed in the external meter box, the recessed kind.

Ive paid attention to opinions of others over the years as this certainly isn’t a new subject and theres plenty of opinion on Google about it. Unless I’ve missed something obvious a general consensus seems to be that putting a consumer unit in a meter box might be frowned on by the suppliers who may need the space for their equipment, but from a BS7671 point of view there aren’t any specific requirements that would prohibit it so long as the box maintains the correct IP rating. 

And then I found myself there in the pouring rain, wind lashing rain drops right into the consumer unit while I was trying to get a Ze reading… And I thought to myself this right now is dangerous. I’m at risk of electric shock and none of this equipment is type tested for get wet in any way, an explosive short of the main switches live terminals seemed inevitable if I continued. In the short term I felt it necessary to close the lid and wait… and wait…. 

So now I’m asking myself does this experience justify a C2? Regulation 513. requires that “every item of equipment shall be arranged so as to facilitate its operation, inspection and maintenance and access to each connection. Regulation 522.3.1 requires that “a wiring system shall be selected and erected so that no damage is caused by condensation or ingress of water during installation, use and maintenance. I felt it was dangerous to inspect and maintain that consumer unit in that location under those environmental conditions. I also feel it may be a concern for old Mrs Smith (not her real name) to go outside in a storm and try to reset an RCD or isolate a circuit if there as a problem, I’d feel more forgiving it it were an industrial location where only skilled or instructed people require access, but this is old Mrs Smith in her bungalow here.

edit also 529.3 requires “Provision shall be made for safe and adequate access to all live parts of a wiring system which may require maintenance.

Has anyone else had to provide an EICR under similar circumstances? Does any one have any advice on how they may code this on an EICR? And does anyone want to offer any other requirements from BS76171 for me to also consider?

Thanks for your opinions in advance.

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    Let's avoid the matter of what can go in a meter cupboard by having two adjacent meter cupboards, one of which encloses the DNO's and supplier's tackle, and the other the CU.

    Now we have to refer to multiple British Standards, which could be prohibitively expensive.

    BS 7671

    522.3.1 A wiring system shall be selected and erected so that no damage is caused by condensation or ingress of water during installation, use and maintenance. The completed wiring system shall comply with the IP degree of protection (see BS EN 60529) relevant to the particular location. I take this to mean that, for example, an exposed outdoor lamp fitting would have a minimum rating of, say, IP55.

    (BS 60529 describes IP ratings, but the information is readily available elsewhere.)

    421.1.201 Within domestic (household) premises, consumer units and similar switchgear assemblies shall comply with BS EN 61439-3 and ...

    BS EN 61439-3:2024

    8.2.2 The degree of protection of a DBO shall be at least IP2XC after installation in accordance with the manufacturer's instructions.

    (Note: DBO = distribution board intended to be operated by ordinary persons.)

    So a CU does not need to be waterproof!

    So if a CU affords no protection from water, can it be installed somewhere wet?

    Back to BS 7671

    512.2.4 NOTE: For the purpose of BS 7671, the following classes of external influence are conventionally regarded as normal: ... Other environmental conditions (AC to AS) XX1 of each parameter.

    Now go to Appendix 5 to see what that means (page 493), which is that exposure to water is negligible. So, it appears that BS 7671 assumes that a CU is installed somewhere dry. Does a meter cupboard afford that degree of protection?

    BS 8567:2012

    4.2 Security and weather resistance Commentary on 4.2 A meter cupboard conforming to this British Standard is deemed to protect the meter installation and distribution termination equipment against the ingress of moisture and accidental damage.

    The document is silent on IP rating.

    Putting all of this together, IMHO the situation described merits no code at all. Should "Mrs Smith" need to operate something in the CU in the middle of a storm, we must assume that she will have the common sense to take an umbrella.

  • 0 in reply to Chris Pearson
    Chris Pearson said:
    8.2.2 The degree of protection of a DBO shall be at least IP2XC after installation in accordance with the manufacturer's instructions.

    Does this take into account the following?

    An MCB or RCBO intended for installation in a standard consumer unit for residential or similar settings is typically rated for
    Pollution Degree 2. However, the actual rating can vary depending on the specific product and its intended installation environment, with some harsh-environment RCBOs having a higher Pollution Degree 3 rating.

    Pollution Degree 1: No contamination or only dry, non-conductive pollution is present. This is typical for sealed components or clean-room environments.

    Pollution Degree 2: Non-conductive pollution is common, but temporary condensation may occur, which could cause a temporary decrease in insulation resistance. This applies to most office, laboratory, and household environments.

    Pollution Degree 3: Conductive pollution or dry, non-conductive pollution that becomes conductive due to condensation is present. This is common in industrial or farming environments, construction sites, and boiler rooms.

    Pollution Degree 4: The pollution is conductive and creates persistent conductivity due to conductive dust, rain, or snow. This is typically found in outdoor environments with no enclosure. 

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  • 0 in reply to Chris Pearson
    Chris Pearson said:
    8.2.2 The degree of protection of a DBO shall be at least IP2XC after installation in accordance with the manufacturer's instructions.

    Does this take into account the following?

    An MCB or RCBO intended for installation in a standard consumer unit for residential or similar settings is typically rated for
    Pollution Degree 2. However, the actual rating can vary depending on the specific product and its intended installation environment, with some harsh-environment RCBOs having a higher Pollution Degree 3 rating.

    Pollution Degree 1: No contamination or only dry, non-conductive pollution is present. This is typical for sealed components or clean-room environments.

    Pollution Degree 2: Non-conductive pollution is common, but temporary condensation may occur, which could cause a temporary decrease in insulation resistance. This applies to most office, laboratory, and household environments.

    Pollution Degree 3: Conductive pollution or dry, non-conductive pollution that becomes conductive due to condensation is present. This is common in industrial or farming environments, construction sites, and boiler rooms.

    Pollution Degree 4: The pollution is conductive and creates persistent conductivity due to conductive dust, rain, or snow. This is typically found in outdoor environments with no enclosure. 

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