The second step in selecting a ferrule is to identify the conductor size. There may be a need to convert from metric wire sizes to AWG (American Wire Gauge) sizes. See the Metric Conversion Guide for more information.

The third step in selecting a ferrule is to determine how long the barrel should be. Three lengths are
available: normal, medium, and long barrels. The actual barrel length varies depending on the wire size capacity of the ferrule. Most applications require the normal length; however, ferrules with longer barrels are available in most sizes.

The fourth step in selecting a ferrule is to select the ferrule color coding system you want to use. There are three different ferrule color coding systems available. Our stock color for the ferrule insulator is based on the DIN (Deutsches Institut fur Normung) system. The color coding is arranged according to DIN 46228 Teil 4. (Note: Uninsulated ferrules are not color coded.) Other color schemes are available by special order with a minimum quantity of 1,000 pieces and a lead-time of four to six weeks.

The fifth step in selecting a ferrule is to determine if the application requires a double wire ferrule. Double wire ferrules are available only in insulated versions and are designed to accept only two wires. If you are using two AWG wires of the same size in a ferrule, you can determine the correct ferrule size by increasing the total wire size by three steps. For example, two 20AWG wires (cross sectional area of 0.519 mm² each) are equivalent to a single 17AWG/1.04 mm². Therefore, you would specify a 1.5mm² capacity ferrule. In theory, two 20AWG wires might fit into a 1.0mm² capacity ferrule, however, they are likely to be a tight fit. Per UL 1581, table 20.1

If you are using two metric wires, two 0.75mm² wires will fit comfortably into a 2 x 0.75mm² ferrule. The ferrules are made of tin plated copper, and the insulation is a polyamide. The temperature rating is 110°C.

Although ferrules are commonly used in Europe, they are not well known in North America. Part of the reason is that much of the equipment production in Europe centers around machinery. Interconnections in machinery are usually based on terminal blocks and other connections that make screw connections desirable. In North America (where electronic equipment production focuses on computers, telecommunications, and medical equipment) interconnections are typically very small, and terminal blocks are inappropriate in many cases. These devices are usually approved in Europe as part of the equipment. They do not have separate approvals. In North America, they are also subject to evaluation at the time the equipment is evaluated by UL and CSA for certification.

All Interpower styles of ferrules come in packages of 100.