Extension sockets are built in an extension box, which makes use of electricity in our homes, offices and various other places convenient. We would be constructing an electrical extension with the following equipment; screw-driver, nails and screws, wooden plank, flexible wire. An extension box is a block of electrical sockets that attaches to the end of a flexible cable (typically with a mains plug on the other end), allowing multiple electrical devices to be powered from a single electrical socket. Extension box which is an electrical device needs maintenance to keep it lifespan long as much as possible. Been an electrical device also makes it very dangerous and it can cause electric shock on the victim. In this seminar work, we discussed the maintenance and safety of extension box.