Box Spanners

About Box Spanners

Box spanners are specialised cylindrical hand tools designed to access and turn fasteners in confined spaces where conventional spanners and sockets cannot reach. Featuring hexagonal or bi-hexagonal internal profiles, these tubular tools excel at plumbing applications, particularly when installing or removing tap back nuts, basin waste fittings, and monobloc mixer taps. The extended tubular design allows the spanner to slide over long threaded sections, making them indispensable for working beneath sinks, basins, and baths where access is severely restricted.

MyToolShed.co.uk stocks a comprehensive range of box spanners from trusted manufacturers including Sealey, Faithfull, Monument, and Draper. Available in metric, imperial, and Whitworth sizing systems, our selection includes individual spanners for specific tasks and multi-piece sets that provide complete coverage for professional tradespeople and DIY enthusiasts. Most sets are supplied with tommy bars that insert through holes in the spanner body, delivering the leverage necessary to apply proper torque without damaging chrome-plated fixtures or fittings.

Applications

• Plumbers and heating engineers – installing and servicing taps, accessing back nuts, radiator connections, and confined pipework
• Bathroom fitters – monobloc tap installations, basin waste connections, and sanitary ware fitting
• Kitchen fitters – sink tap installations, waste disposal units, and under-sink plumbing work
• Property maintenance teams – routine repairs and replacements in residential and commercial buildings
• DIY enthusiasts – bathroom renovations, tap replacements, and general household plumbing repairs
• Maintenance engineers – accessing recessed fasteners on machinery, boilers, and industrial equipment
• Gas engineers – appliance connections requiring precise torque in restricted spaces

Choosing The Right Box Spanners

Sizing system: Determine whether you need metric, imperial, or Whitworth sizes. Modern UK plumbing uses predominantly metric sizing, but older properties often feature imperial fittings. Professional tradespeople benefit from comprehensive sets covering multiple standards, whilst DIY users might select individual sizes for specific projects.

Set or individual purchase: Multi-piece sets from brands stocked at MyToolShed.co.uk offer better value and ensure correct sizing availability. Options range from compact 3-piece monobloc sets to comprehensive 8-piece metric collections with storage rolls. Individual spanners suit those replacing specific sizes or adding to existing toolkits.

Application type: Consider specialist variants such as monobloc tap spanners (typically 28-32mm for modern mixer taps), waste nut box spanners for larger diameter sink fittings, and angled versions providing additional access in awkward installations.

Material quality: Professional-grade box spanners manufactured from chrome vanadium steel offer superior durability and precise internal machining, reducing fastener rounding risks. Wall thickness should prevent flexing under torque whilst remaining compact for confined spaces.

Tommy bar provision: Check whether tommy bars are included or require separate purchase. Professional sets may include multiple bar lengths for different working conditions.

Safety Information

Always ensure the box spanner is fully engaged with the fastener before applying force to prevent slippage causing injury or fitting damage. Use the correct size—forcing incorrect sizes risks rounding fastener corners. Apply steady, controlled pressure rather than sudden jerking motions, and position yourself safely should the spanner slip or fastener suddenly release.

When working beneath sinks and basins, wear safety glasses to protect against debris, particularly when loosening corroded fittings. Ensure adequate lighting in confined areas and verify tommy bars are properly seated before applying torque. Always isolate water supplies before commencing plumbing work, and be cautious of hot pipes that may cause burns.

Frequently Asked Questions

What size box spanner do I need for a monobloc tap?

Most modern monobloc mixer taps use 28mm, 30mm, or 32mm back nuts, with 32mm being particularly common. Three-piece monobloc box spanner sets typically include these sizes, providing comprehensive coverage for the majority of single-lever mixer tap installations in UK bathrooms and kitchens.

Do I need metric and imperial box spanners?

Modern UK plumbing uses metric sizing almost exclusively, so metric box spanners suffice for new builds and contemporary renovations. However, properties built before the 1970s often feature imperial fittings. Professional plumbers benefit from maintaining both systems, whilst DIY users should assess their specific property's requirements.

Can I use an adjustable spanner instead of a box spanner?

Adjustable spanners rarely work effectively in confined spaces beneath basins where box spanners excel. They require clearance for the moveable jaw and handle, which often isn't available, and provide less secure grip, potentially damaging chrome-plated fixtures. Box spanners deliver superior access and controlled force application for plumbing installations.