Trench for SWA to be laid

Hello Jack, In years gone by there were specific depths for electric/gas/water, nowadays the supply authorities barely scrape away the topsoil. In your case burying the SWA it is less critical so long as the earthing rules are applied. 1. the SWA (steel) must be earthed at source and protected by a 30 milliamp RCD. The load end ( your workshop) no earth to be connected to the SWA. Here you will form a TT earthing system (buried copper rod) and that will be your segregated earthing for this area. Bear in mind your load requirement here. If you are running some lights and say a couple of sockets you might be drawing around 18 amps, in which case, over that distance, you will need a 10mm 2 core SWA cable Regards Mike

The work planned is notifiable work, your electrician will need to sign off and certify the work undertaken to building control. Speak to the electrician, agree a plan before you dig. You dont want to dig 600mm to find that they want 800mm to enable sign off.

There is no hard and fast rule. it must be buried to a sufficient depth to prevent damage and that depth will vary according to each installation and environment.