WL9 - Electrical Bonding Labels The WL9 Electrical Bonding Labels have been updated to reflect the revised wording for this type of label recommended by the publication of BS 6891:2015. The Electrical Bonding Labels, which are self-adhesive, give the gas user important information in a clear and easy-to-understand manner that their gas installation appears to have no main equipotential bonding provision in place and that they should contact an approved electrical contractor to check the installation. Please be aware that you need to be Gas Safe Registered to be able to purchase this product.