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1 Gang 25mm Galvanised Steel Extension Box

£149
The RRP is the manufacturer's recommended retail price of the item.
Limited Stock
We are an Independent UK Company
Price match. Found it cheaper? Contact us
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Minimum order for this item is 10.

Description

The Knightsbridge GSE25 is a 1-gang 25mm galvanised steel extension box designed to add depth to existing flush-mounted back boxes when deeper accessories are being fitted or when a back box has been recessed too far into the wall. The box measures 72mm x 72mm to match standard single-gang back boxes and adds 25mm of usable depth. It's constructed from 1.0mm thick galvanised steel with an earth terminal and one adjustable mounting lug.

Used in residential, commercial and industrial electrical installations, the extension box accommodates switches, sockets and other accessories that exceed the depth capacity of a standard 25mm back box. Multiple 20mm knockouts on each side allow cables to enter from any direction, giving flexibility in routing cable runs without drilling additional holes. The adjustable lug provides fine-tuning of the faceplate position once the box is fitted.

Galvanisation provides corrosion resistance in damp environments or outdoor-sheltered locations where the box is protected from direct water ingress. The 1.0mm steel gauge gives rigidity under load, preventing the box from flexing when deep accessories are screwed into the mounting lug. The earth terminal connects the metal box to the circuit earth, maintaining electrical safety where metal faceplates are used.

Specification
Height 72 mm
Width 72 mm
Recessed Depth 25 mm
Construction Steel
Earth Terminal Yes
Warranty 25
Downloads

Product Specification Sheet

Frequently Asked

When would I need an extension box?

Extension boxes are used when fitting deeper electrical accessories into existing back boxes, when a back box has been recessed too far into the wall during plastering, or when cable routing requires additional internal space behind the accessory. They add 25mm of depth without chasing out more wall.

Does it fit standard back boxes?

Yes. The 72mm x 72mm footprint matches standard single-gang UK back boxes. The extension box sits over the existing back box and is fixed to the wall surface or plasterboard, not to the recessed box itself.

How is it earthed?

The box includes an earth terminal. Connect the circuit earth cable to this terminal to earth the metal box, which is required under UK wiring regulations when metal faceplates or accessories are used.

Can it be used outdoors?

The galvanised steel provides corrosion resistance suitable for sheltered outdoor locations where the box is protected from direct rain. It is not rated for full outdoor exposure without additional weatherproof housing.

Shipping & Returns

Delivery UK delivery is £14.99, and delivery is free on all orders of £99 or more, in the UK and internationally.

Returns If you change your mind, you have 14 days from delivery to tell us, and a further 14 days to send the goods back. Return postage for a change-of-mind return is paid by you. Change-of-mind returns are subject to an inspection and handling deduction. See our full returns policy.

To arrange a return, call us on 020 8149 5199 or use our contact page.

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Free delivery on orders over £99, in the UK and worldwide. Easy returns within 14 days, subject to our returns policy. Full manufacturer warranty included.

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    Description

    The Knightsbridge GSE25 is a 1-gang 25mm galvanised steel extension box designed to add depth to existing flush-mounted back boxes when deeper accessories are being fitted or when a back box has been recessed too far into the wall. The box measures 72mm x 72mm to match standard single-gang back boxes and adds 25mm of usable depth. It's constructed from 1.0mm thick galvanised steel with an earth terminal and one adjustable mounting lug.

    Used in residential, commercial and industrial electrical installations, the extension box accommodates switches, sockets and other accessories that exceed the depth capacity of a standard 25mm back box. Multiple 20mm knockouts on each side allow cables to enter from any direction, giving flexibility in routing cable runs without drilling additional holes. The adjustable lug provides fine-tuning of the faceplate position once the box is fitted.

    Galvanisation provides corrosion resistance in damp environments or outdoor-sheltered locations where the box is protected from direct water ingress. The 1.0mm steel gauge gives rigidity under load, preventing the box from flexing when deep accessories are screwed into the mounting lug. The earth terminal connects the metal box to the circuit earth, maintaining electrical safety where metal faceplates are used.

    Specification
    Height 72 mm
    Width 72 mm
    Recessed Depth 25 mm
    Construction Steel
    Earth Terminal Yes
    Warranty 25
    Downloads

    Product Specification Sheet

    Frequently Asked

    When would I need an extension box?

    Extension boxes are used when fitting deeper electrical accessories into existing back boxes, when a back box has been recessed too far into the wall during plastering, or when cable routing requires additional internal space behind the accessory. They add 25mm of depth without chasing out more wall.

    Does it fit standard back boxes?

    Yes. The 72mm x 72mm footprint matches standard single-gang UK back boxes. The extension box sits over the existing back box and is fixed to the wall surface or plasterboard, not to the recessed box itself.

    How is it earthed?

    The box includes an earth terminal. Connect the circuit earth cable to this terminal to earth the metal box, which is required under UK wiring regulations when metal faceplates or accessories are used.

    Can it be used outdoors?

    The galvanised steel provides corrosion resistance suitable for sheltered outdoor locations where the box is protected from direct rain. It is not rated for full outdoor exposure without additional weatherproof housing.

    Shipping & Returns

    Delivery UK delivery is £14.99, and delivery is free on all orders of £99 or more, in the UK and internationally.

    Returns If you change your mind, you have 14 days from delivery to tell us, and a further 14 days to send the goods back. Return postage for a change-of-mind return is paid by you. Change-of-mind returns are subject to an inspection and handling deduction. See our full returns policy.

    To arrange a return, call us on 020 8149 5199 or use our contact page.