Metal Back Boxes

About Metal Back Boxes

Metal back boxes are essential electrical components used to house sockets, switches, and other wiring accessories within walls. Manufactured from galvanised steel, these robust mounting boxes provide superior fire resistance and structural strength compared to plastic alternatives, making them the preferred choice for professional electricians working to BS 7671 wiring regulations. MyToolShed.co.uk stocks a range of metal back boxes in single and double socket configurations from trusted brands including Axiom and SMJ.

Available in various depths to accommodate different cable requirements and wall constructions, metal back boxes feature pre-drilled fixing holes and knock-out entry points for conduit and cable. Their rigid construction ensures a secure fixing point for electrical accessories whilst protecting cables from damage during installation and throughout the lifetime of the electrical installation.

Applications

Metal back boxes are used across numerous trades and applications:

• Electricians and sparkies installing 240v mains sockets, switches, and dimmers in domestic, commercial, and industrial properties
• Refurbishment contractors upgrading existing electrical installations to current building regulations
• Construction companies fitting out new builds and extensions
• Maintenance professionals repairing or replacing damaged electrical accessories
• DIY enthusiasts undertaking home improvement projects and rewiring work
• Property developers and landlords ensuring electrical installations meet safety standards
• Fire safety applications where non-combustible materials are specified

Choosing The Right Metal Back Boxes

When selecting metal back boxes from MyToolShed.co.uk, consider these key factors:

• Gang size: Choose single boxes for individual sockets or switches, or double boxes for twin accessories
• Depth: Standard depths range from 16mm to 47mm – deeper boxes accommodate more cables and larger accessories, whilst shallow boxes suit dot-and-dab plasterboard walls
• Wall type: Consider whether you're fixing to solid masonry, stud walls, or plasterboard to ensure adequate fixing depth
• Entry points: Check the number and position of knock-outs for cable entry, particularly important for multiple circuits
• Fixing lugs: Ensure the box has appropriate screw positions compatible with your chosen accessories
• Regulations compliance: Verify products meet BS 4662 and BS 8519 standards for electrical mounting boxes

Safety Information

All electrical installation work must comply with BS 7671 (IEE Wiring Regulations) and Part P of the Building Regulations. In England and Wales, any work adding new circuits or work in special locations must be carried out by a qualified electrician or certified under a Competent Person Scheme. Always isolate the electrical supply before commencing work. Metal back boxes must be properly earthed to prevent electric shock hazards. Ensure adequate cable capacity within the box to prevent overheating.

Frequently Asked Questions

Why choose metal over plastic back boxes?

Metal back boxes offer superior fire resistance, greater structural strength, and are often specified in commercial installations or where building regulations require non-combustible materials. They're also more durable during installation in high-traffic construction environments.

What depth back box do I need?

Standard 25mm or 35mm boxes suit most single-circuit installations. Choose 47mm deep boxes when accommodating multiple cables, larger accessories like dimmer switches, or where extra space improves heat dissipation for high-load circuits.

Can I use metal back boxes with plasterboard walls?

Yes, but you'll need dry lining boxes specifically designed for plasterboard installation, or ensure adequate fixing to studs or noggings behind the plasterboard to support the weight of the metal box and accessory.