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1 Gang 25mm Galvanised Steel Back Box

£149
The RRP is the manufacturer's recommended retail price of the item.
Limited Stock
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Minimum order for this item is 10.

Description

The Knightsbridge GSK25 is a 1-gang galvanised steel back box with a 25mm recessed depth, designed to house switches, sockets and dimmers in residential, commercial and industrial installations. The box measures 73mm x 73mm at the face and is pressed from 1mm-thick galvanised steel, providing corrosion resistance and structural rigidity when fixed into masonry, plasterboard or dry-lining.

The box features one fixed mounting lug and one adjustable mounting lug, allowing the faceplate to be levelled even where the box sits slightly off-square in the wall. An integrated earth terminal provides a connection point for protective earth continuity, meeting UK wiring regulation requirements. Multiple 20mm knockouts on the sides and rear accept standard PVC conduit, flexible conduit or cable entries, giving flexibility for both surface-fed and back-fed wiring runs.

The 25mm depth suits installations where wall cavity space is limited, including single-skin blockwork, timber stud partitions with 12.5mm plasterboard, and retrofits into existing shallow chases. The galvanised finish protects the steel from oxidation in damp conditions during the construction phase and throughout the life of the installation. The box accepts all standard 1-gang switches, sockets and dimmers from Knightsbridge and other manufacturers using the 73mm x 73mm British Standard mounting pattern.

Specification
Height 73 mm
Width 73 mm
Recessed Depth 25 mm
Construction Steel
Earth Terminal Yes
Warranty 25
Downloads

Product Specification Sheet

Frequently Asked

What wall constructions suit a 25mm back box?

The 25mm depth works in single-skin blockwork, timber stud partitions with 12.5mm plasterboard, and shallow chases in solid walls where a deeper box cannot be accommodated. For dry-lining installations, ensure the plasterboard thickness plus the box depth does not exceed the available cavity space.

Are the mounting lugs adjustable?

One lug is fixed and one is adjustable. The adjustable lug allows the faceplate to be levelled if the box is slightly off-square in the wall, which is common in retrofit installations or where the chase was cut by hand.

What size knockouts does it have?

The box has 20mm knockouts on the sides and rear, accepting standard 20mm PVC conduit, flexible conduit or grommeted cable entries. Knockouts are punched out with a screwdriver or similar tool during installation.

Is the earth terminal compliant with UK wiring regulations?

Yes. The integrated earth terminal provides a connection point for protective earth continuity as required by BS 7671 (the IET Wiring Regulations). The galvanised steel construction provides an effective earth path when correctly bonded.

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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    Description

    The Knightsbridge GSK25 is a 1-gang galvanised steel back box with a 25mm recessed depth, designed to house switches, sockets and dimmers in residential, commercial and industrial installations. The box measures 73mm x 73mm at the face and is pressed from 1mm-thick galvanised steel, providing corrosion resistance and structural rigidity when fixed into masonry, plasterboard or dry-lining.

    The box features one fixed mounting lug and one adjustable mounting lug, allowing the faceplate to be levelled even where the box sits slightly off-square in the wall. An integrated earth terminal provides a connection point for protective earth continuity, meeting UK wiring regulation requirements. Multiple 20mm knockouts on the sides and rear accept standard PVC conduit, flexible conduit or cable entries, giving flexibility for both surface-fed and back-fed wiring runs.

    The 25mm depth suits installations where wall cavity space is limited, including single-skin blockwork, timber stud partitions with 12.5mm plasterboard, and retrofits into existing shallow chases. The galvanised finish protects the steel from oxidation in damp conditions during the construction phase and throughout the life of the installation. The box accepts all standard 1-gang switches, sockets and dimmers from Knightsbridge and other manufacturers using the 73mm x 73mm British Standard mounting pattern.

    Specification
    Height 73 mm
    Width 73 mm
    Recessed Depth 25 mm
    Construction Steel
    Earth Terminal Yes
    Warranty 25
    Downloads

    Product Specification Sheet

    Frequently Asked

    What wall constructions suit a 25mm back box?

    The 25mm depth works in single-skin blockwork, timber stud partitions with 12.5mm plasterboard, and shallow chases in solid walls where a deeper box cannot be accommodated. For dry-lining installations, ensure the plasterboard thickness plus the box depth does not exceed the available cavity space.

    Are the mounting lugs adjustable?

    One lug is fixed and one is adjustable. The adjustable lug allows the faceplate to be levelled if the box is slightly off-square in the wall, which is common in retrofit installations or where the chase was cut by hand.

    What size knockouts does it have?

    The box has 20mm knockouts on the sides and rear, accepting standard 20mm PVC conduit, flexible conduit or grommeted cable entries. Knockouts are punched out with a screwdriver or similar tool during installation.

    Is the earth terminal compliant with UK wiring regulations?

    Yes. The integrated earth terminal provides a connection point for protective earth continuity as required by BS 7671 (the IET Wiring Regulations). The galvanised steel construction provides an effective earth path when correctly bonded.

    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.