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Thoughts on replacing switched fuse with small consumer unit

Alan B

I need to take a garage feed from the meter box in the picture below to enable installation of an EV charger. as consume unit is in the middle of the house and far from easy to get a cable in to it.

My initial plan has been to use an external IP rated consumer unit connected by henley blocks to the output of the main isolator.

Then I have been thinking that looking at the real estate taken by the current switched fuse (protecting cable run through house) and the Henley block I need it's basically the same size as a small garage consumer unit, probably more untidy. 

I know the DNO's frown on consumer units in the meter cupboard but given the switched fuse and henley blocks would have to be there anyway and I think there is a reasonable argument for a small consumer unit being a neater and in some ways more space efficient solution.

I would mount the new CU on spacers so that the meter tails could run underneath to the isolator above and maybe move the isolator up a bit, SWA garage feed would come up from the bottom.

The alternative would be to move the isolator up, squeeze a Henley block between it and the switched fuse.

Does this sound like  reasonable engineering judgement, anything I am missing?

Thanks

  • 0

    I am going down the flush mount meter box route mainly because of aesthetics, I think the surface mount ones look very big and ugly. I was going to use an IP rated consumer unit and that's big enough.

    I have found retrofit cavity trays that can be installed reasonably easily without having to bed into the inner wall leaf, which removes my biggest concern for installing a flush mount meter box. 

  • 0 in reply to Sparkingchip

    Which was a point that I made earlier.

  • 0

    They aren’t designed to touch each other, they need a brick pier between them as do gas and electric meters.

  • 0 in reply to Sparkingchip

    That's not quite the way that I interpret it.

    8.1.9 Meters

    Openings in walls for meter cabinets shall be structurally adequate and prevent dampness entering the home.

    Openings set into external walls should be provided with:

    • DPCs and cavity trays
    • lintels (except for purpose-designed built-in meter boxes).

    I doubt that the purpose-designed boxes are designed to sit side by side with no support between them, but of course, I may be wrong.

  • 0

    Regards meter box installation, definitely needs a cavity tray to direct any water, and there will be some, that runs down the back of the face brickwork out.

    But a lintel is not required.

    nhbc-standards.co.uk/.../

  • 0

    Or loads of spray foam at the shallow end of the quality control

    Cavity trays aren't to close the cavity as such, but to ensure that any water that might drip down inside the cavity gets directed outside before it meets any horizontal barrier that might allow the water to track or splash onto the the inner leaf.  Thus they need to slope downwards to the outside (usually aligned with weep vents) to work.

    As they're next to impossible to install after the wall is built, I reckon they usually just get left out in later work.

       - Andy.

  • 0

    Or loads of spray foam at the shallow end of the quality control - I'm pretty sure that there are suppose to be cavity stops at windows and doors too, but a very large fraction seem to be just stuck in until it oozes like tooth paste and then trimmed flush.  In many ways the easy but slightly cop-out solution is to find someone who does brickwork for a living to make the aperture for you, as the job then reduces to the use of two pens - a large marker pen to show where you want the hole, and a second smaller one to sign the cheque. Nowadays the second pen can be replaced by BACS....

    A similar thought occurs when you are too old to dig trenches for SWA any more.

    Mike

  • 0

    There won’t be a lintel above a meter box in a cavity wall, but there should be a cavity tray.

  • 0 in reply to Alan B
    Alan B said:
    I have to agree that in my mind an additional flush meter box is the best solution,

    Any particular reason for not fitting a surface mounted meter box? You could then put it quite close to the flush one (possibly above it so it is out of the way? Or around the corner <3M away?) move the switchfuse into it to keep DNO happy and have your garage unit or whatever.

  • 0 in reply to Alan B

    If it were my house, I'd want a lintel, but regardless, there needs to be a brick pier between the two holes.

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