Silverline - FIBREGLASS SQUARE MOUTH SHOVEL - 633659 Insulated fibre glass handled range of shovels and spades. Each and every shovel and spade is individually tested to withstand 10,000V. Meet BS 8020: 2002 for work on or near conductor rail systems operating at voltages up to 1,000 V a.c. or 1,500 V d.c.