This article needs additional citations for verification. (May 2013) (Learn how and when to remove this template message)
The pipes to be joined are cleaned, inserted into the electrofusion fitting (with a temporary clamp if required) and a voltage (typically 40V) is applied for a fixed time depending on the fitting in use. The built in heater coils then melt the inside of the fitting and the outside of the pipe wall, which weld together producing a very strong homogeneous joint. The assembly is then left to cool for a specified time.
Electrofusion welding is beneficial because it does not require the operator to use dangerous or sophisticated equipment. After some preparation, the Electrofusion Welder will guide the operator through the steps to take. Welding Heat and Time is dependant on the type and size of the fitting. All Electrofusion Fittings are not created equal - Precise positioning of the energising coils of wire in each fitting ensures uniform melting for a strong joint and the minimisation of welding and cooling time. 
The operator must be qualified according to the local and national laws. In Australia, an Electrofusion Course can be done within 8 hours. Electrofusion welding training focuses on the importance of accurately fusing EF fittings. Looking at both manual and automatic fittings you will learn the importance of preparation, timing, temperature, pressure, cool down etc. 
To keep their qualification current, a trained operator can get their fitting tested, which involves cutting open the fitting and examining the integrity of the weld.