Over the years there have been a number of in-flight smoke and fire events where contaminants ignited by electrical faults allowed the fire to be sustained and spread. The FAA and the National Transportation Safety Board (NTSB) have conducted aircraft inspections and found wiring contaminated with items such as dust, dirt, metal shavings, lavatory waste water, coffee, soft drinks, and napkins. Sometimes wire bundles and surrounding areas have been found to be completely covered with dust.
 
In recent years both the FAA & Industry have realized that current maintenance practices may not be enough to address aging non-structural systems. Over time, insulation can crack or breach, thus exposing the conductor.

EWIS Stands for Electrical Wiring Interconnect System and it is an abbreviation for something which has been around a long time. In fact any wiring, even a single wire may be considered as EWIS.
 
Training related to Electrical Wiring Interconnect System (EWIS) was introduced by European Aviation Safety Agency (EASA) in August / September 2008. The details were to be found in 3 Acceptable Means of Compliance (AMC) documents, specifically AMC 20-21, AMC 20-22, AMC 20-23.
 
EWIS is Mandatory training requiring both Initial and Recurrent elements with details of the identified groups being detailed in AMC 20-22.

Have you attended Fuel Tank Safety Initial Training?

The criteria requires that persons working on Aircraft which carry more than 30 passengers or 7500 lb of Cargo should satisfy the requirements of Fuel Tank Safety Training Level 2.

The Training required should cover a wide range of associated topics the subject material is driven by the EASA requirements and covers an understanding, from the investigation of historical events driving the legislation, to its practical applications ensuring the continued airworthiness of affected aircraft.