Use the correct safety equipment and clothing. Remeber: gloves, clothes and shoes. Electrical cables and equipment are not 100% efficient. For every kiloWatt of power passing through there will be a few watts of heat dissipated in the cable due to the resistance in the copper (or other) conductors and the losses in electronic components. This heat will cause the equipment to heat up. How much it heats up depends on how fast the heat is conducted away from the cable or the equipment.